c#多线程总结（纯干货）

static void Main(string[] args)
{
    Thread t = new Thread(PrintNumbers);
    t.Start();//线程开始执行
    PrintNumbers();
    Console.ReadKey();
}

static void PrintNumbers()
{
    Console.WriteLine("Starting...");
    for (int i = 1; i < 10; i++)
    {
        Console.WriteLine(i);
    }
}

class Program
{
    static void Main(string[] args)
    {
        Thread t = new Thread(PrintNumbersWithDelay);
        t.Start();
        PrintNumbers();
        Console.ReadKey();
    }

    static void PrintNumbers()
    {
        Console.WriteLine("Starting...");
        for (int i = 1; i < 10; i++)
        {
            Console.WriteLine(i);
        }
    }

    static void PrintNumbersWithDelay()
    {
        Console.WriteLine("Starting...");
        for (int i = 1; i < 10; i++)
        {
            Thread.Sleep(TimeSpan.FromSeconds(2));//暂停2S
            Console.WriteLine(i);
        }
    }
}

class Program
{
    static void Main(string[] args)
    {
        Console.WriteLine("Starting program...");
        Thread t = new Thread(PrintNumbersWithDelay);
        t.Start();
        t.Join();
        Console.WriteLine("Thread completed");
    }

    static void PrintNumbersWithDelay()
    {
        Console.WriteLine("Starting...");
        for (int i = 1; i < 10; i++)
        {
            Thread.Sleep(TimeSpan.FromSeconds(2));
            Console.WriteLine(i);
        }
    }
}

class Program
{
    static void Main(string[] args)
    {
        Console.WriteLine("Starting program...");
        Thread t = new Thread(PrintNumbersWithDelay);
        t.Start();
        Thread.Sleep(TimeSpan.FromSeconds(6));
        t.Abort();
        Console.WriteLine("A thread has been aborted");
    }

    static void PrintNumbersWithDelay()
    {
        Console.WriteLine("Starting...");
        for (int i = 1; i < 10; i++)
        {
            Thread.Sleep(TimeSpan.FromSeconds(2));
            Console.WriteLine(i);
        }
    }
}

class Program
{
    static void Main(string[] args)
    {
        Console.WriteLine("Starting program...");
        Thread t = new Thread(PrintNumbersWithStatus);
        Thread t2 = new Thread(DoNothing);
        Console.WriteLine(t.ThreadState.ToString());
        t2.Start();
        t.Start();
        for (int i = 1; i < 30; i++)
        {
            Console.WriteLine(t.ThreadState.ToString());
        }
        Thread.Sleep(TimeSpan.FromSeconds(6));
        t.Abort();
        Console.WriteLine("A thread has been aborted");
        Console.WriteLine(t.ThreadState.ToString());
        Console.WriteLine(t2.ThreadState.ToString());

        Console.ReadKey();
    }

    static void DoNothing()
    {
        Thread.Sleep(TimeSpan.FromSeconds(2));
    }

    static void PrintNumbersWithStatus()
    {
        Console.WriteLine("Starting...");
        Console.WriteLine(Thread.CurrentThread.ThreadState.ToString());
        for (int i = 1; i < 10; i++)
        {
            Thread.Sleep(TimeSpan.FromSeconds(2));
            Console.WriteLine(i);
        }
    }
}

class Program
{
    static void Main(string[] args)
    {
        Console.WriteLine("Current thread priority: {0}", Thread.CurrentThread.Priority);
        Console.WriteLine("Running on all cores available");
        RunThreads();
        Thread.Sleep(TimeSpan.FromSeconds(2));
        Console.WriteLine("Running on a single core");
        Process.GetCurrentProcess().ProcessorAffinity = new IntPtr(1);
        RunThreads();
    }

    static void RunThreads()
    {
        var sample = new ThreadSample();

        var threadOne = new Thread(sample.CountNumbers);
        threadOne.Name = "ThreadOne";
        var threadTwo = new Thread(sample.CountNumbers);
        threadTwo.Name = "ThreadTwo";

        threadOne.Priority = ThreadPriority.Highest;
        threadTwo.Priority = ThreadPriority.Lowest;
        threadOne.Start();
        threadTwo.Start();

        Thread.Sleep(TimeSpan.FromSeconds(2));
        sample.Stop();

        Console.ReadKey();
    }

    class ThreadSample
    {
        private bool _isStopped = false;

        public void Stop()
        {
            _isStopped = true;
        }

        public void CountNumbers()
        {
            long counter = 0;

            while (!_isStopped)
            {
                counter++;
            }

            Console.WriteLine("{0} with {1,11} priority " +
                        "has a count = {2,13}", Thread.CurrentThread.Name,
                        Thread.CurrentThread.Priority,
                        counter.ToString("N0"));
        }
    }
}

class Program
{
    static void Main(string[] args)
    {
        var sampleForeground = new ThreadSample(10);
        var sampleBackground = new ThreadSample(20);

        var threadOne = new Thread(sampleForeground.CountNumbers);
        threadOne.Name = "ForegroundThread";
        var threadTwo = new Thread(sampleBackground.CountNumbers);
        threadTwo.Name = "BackgroundThread";
        threadTwo.IsBackground = true;

        threadOne.Start();
        threadTwo.Start();

        Console.ReadKey();
    }

    class ThreadSample
    {
        private readonly int _iterations;

        public ThreadSample(int iterations)
        {
            _iterations = iterations;
        }
        public void CountNumbers()
        {
            for (int i = 0; i < _iterations; i++)
            {
                Thread.Sleep(TimeSpan.FromSeconds(0.5));
                Console.WriteLine("{0} prints {1}", Thread.CurrentThread.Name, i);
            }
        }
    }
}

class Program
{
    static void Main(string[] args)
    {
        var sample = new ThreadSample(10);

        var threadOne = new Thread(sample.CountNumbers);
        threadOne.Name = "ThreadOne";
        threadOne.Start();
        threadOne.Join();

        Console.WriteLine("--------------------------");

        var threadTwo = new Thread(Count);
        threadTwo.Name = "ThreadTwo";
        threadTwo.Start(8);
        threadTwo.Join();

        Console.WriteLine("--------------------------");

        var threadThree = new Thread(() => CountNumbers(12));
        threadThree.Name = "ThreadThree";
        threadThree.Start();
        threadThree.Join();
        Console.WriteLine("--------------------------");

        int i = 10;
        var threadFour = new Thread(() => PrintNumber(i));
        i = 20;
        var threadFive = new Thread(() => PrintNumber(i));
        threadFour.Start(); 
        threadFive.Start();
    }

    static void Count(object iterations)
    {
        CountNumbers((int)iterations);
    }

    static void CountNumbers(int iterations)
    {
        for (int i = 1; i <= iterations; i++)
        {
            Thread.Sleep(TimeSpan.FromSeconds(0.5));
            Console.WriteLine("{0} prints {1}", Thread.CurrentThread.Name, i);
        }
    }

    static void PrintNumber(int number)
    {
        Console.WriteLine(number);
    }

    class ThreadSample
    {
        private readonly int _iterations;

        public ThreadSample(int iterations)
        {
            _iterations = iterations;
        }
        public void CountNumbers()
        {
            for (int i = 1; i <= _iterations; i++)
            {
                Thread.Sleep(TimeSpan.FromSeconds(0.5));
                Console.WriteLine("{0} prints {1}", Thread.CurrentThread.Name, i);
            }
        }
    }
}

class Program
{
    static void Main(string[] args)
    {
        Console.WriteLine("Incorrect counter");

        var c = new Counter();

        var t1 = new Thread(() => TestCounter(c));
        var t2 = new Thread(() => TestCounter(c));
        var t3 = new Thread(() => TestCounter(c));
        t1.Start();
        t2.Start();
        t3.Start();
        t1.Join();
        t2.Join();
        t3.Join();

        Console.WriteLine("Total count: {0}",c.Count);
        Console.WriteLine("--------------------------");

        Console.WriteLine("Correct counter");

        var c1 = new CounterWithLock();

        t1 = new Thread(() => TestCounter(c1));
        t2 = new Thread(() => TestCounter(c1));
        t3 = new Thread(() => TestCounter(c1));
        t1.Start();
        t2.Start();
        t3.Start();
        t1.Join();
        t2.Join();
        t3.Join();
        Console.WriteLine("Total count: {0}", c1.Count);

        Console.ReadKey();

    }

    static void TestCounter(CounterBase c)
    {
        for (int i = 0; i < 100000; i++)
        {
            c.Increment();
            c.Decrement();
        }
    }

    class Counter : CounterBase
    {
        public int Count { get; private set; }

        public override void Increment()
        {
            Count++;
        }

        public override void Decrement()
        {
            Count--;
        }
    }

    class CounterWithLock : CounterBase
    {
        private readonly object _syncRoot = new Object();

        public int Count { get; private set; }

        public override void Increment()
        {
            lock (_syncRoot)
            {
                Count++;
            }
        }

        public override void Decrement()
        {
            lock (_syncRoot)
            {
                Count--;
            }
        }
    }

    abstract class CounterBase
    {
        public abstract void Increment();

        public abstract void Decrement();
    }
}

class Program
{
    static void Main(string[] args)
    {
        object lock1 = new object();
        object lock2 = new object();

        new Thread(() => LockTooMuch(lock1, lock2)).Start();

        lock (lock2)
        {
            Thread.Sleep(1000);
            Console.WriteLine("Monitor.TryEnter allows not to get stuck, returning false after a specified timeout is elapsed");
            if (Monitor.TryEnter(lock1, TimeSpan.FromSeconds(5)))
            {
                Console.WriteLine("Acquired a protected resource succesfully");
            }
            else
            {
                Console.WriteLine("Timeout acquiring a resource!");
            }
        }

        new Thread(() => LockTooMuch(lock1, lock2)).Start();

        Console.WriteLine("----------------------------------");
        lock (lock2)
        {
            Console.WriteLine("This will be a deadlock!");
            Thread.Sleep(1000);
            lock (lock1)
            {
                Console.WriteLine("Acquired a protected resource succesfully");
            }
        }

        Console.ReadKey();
    }

    static void LockTooMuch(object lock1, object lock2)
    {
        lock (lock1)
        {
            Thread.Sleep(1000);
            lock (lock2);
        }
    }
}

bool acquiredLock = false;
try
{
    Monitor.Enter(lockObject, ref acquiredLock);
}
finally 
{
    if (acquiredLock)
    {
        Monitor.Exit(lockObject);
    }
}

class Program
{
    static void Main(string[] args)
    {
        var t = new Thread(FaultyThread);
        t.Start();
        t.Join();

        try
        {
            t = new Thread(BadFaultyThread);
            t.Start();
        }
        catch (Exception ex)
        {
            Console.WriteLine("We won‘t get here!");
        }
    }

    static void BadFaultyThread()
    {
        Console.WriteLine("Starting a faulty thread...");
        Thread.Sleep(TimeSpan.FromSeconds(2));
        throw new Exception("Boom!");
    }

    static void FaultyThread()
    {
        try
        {
            Console.WriteLine("Starting a faulty thread...");
            Thread.Sleep(TimeSpan.FromSeconds(1));
            throw new Exception("Boom!");
        }
        catch (Exception ex)
        {
            Console.WriteLine("Exception handled: {0}", ex.Message);
        }
    }
}

<configuration>
  <runtime>
    <legacyUnhandledExceptionPolicy enable="1" />
  </runtime>
</configuration>

internal class Program
{
    private static void Main(string[] args)
    {
        Console.WriteLine("Incorrect counter");

        var c = new Counter();

        var t1 = new Thread(() => TestCounter(c));
        var t2 = new Thread(() => TestCounter(c));
        var t3 = new Thread(() => TestCounter(c));
        t1.Start();
        t2.Start();
        t3.Start();
        t1.Join();
        t2.Join();
        t3.Join();

        Console.WriteLine("Total count: {0}", c.Count);
        Console.WriteLine("--------------------------");

        Console.WriteLine("Correct counter");

        var c1 = new CounterNoLock();

        t1 = new Thread(() => TestCounter(c1));
        t2 = new Thread(() => TestCounter(c1));
        t3 = new Thread(() => TestCounter(c1));
        t1.Start();
        t2.Start();
        t3.Start();
        t1.Join();
        t2.Join();
        t3.Join();

        Console.WriteLine("Total count: {0}", c1.Count);

        Console.ReadKey();
    }

    static void TestCounter(CounterBase c)
    {
        for (int i = 0; i < 100000; i++)
        {
            c.Increment();
            c.Decrement();
        }
    }

    class Counter : CounterBase
    {
        private int _count;

        public int Count { get { return _count; } }

        public override void Increment()
        {
            _count++;
        }

        public override void Decrement()
        {
            _count--;
        }
    }

    class CounterNoLock : CounterBase
    {
        private int _count;

        public int Count { get { return _count; } }

        public override void Increment()
        {
            Interlocked.Increment(ref _count);
        }

        public override void Decrement()
        {
            Interlocked.Decrement(ref _count);
        }
    }

    abstract class CounterBase
    {
        public abstract void Increment();

        public abstract void Decrement();
    }
}

class Program
{
    static void Main(string[] args)
    {
        const string MutexName = "CSharpThreadingCookbook";

        using (var m = new Mutex(false, MutexName))
        {
            if (!m.WaitOne(TimeSpan.FromSeconds(5), false))
            {
                Console.WriteLine("Second instance is running!");
            }
            else
            {
                Console.WriteLine("Running!");
                Console.ReadLine();
                m.ReleaseMutex();
            }
        }
    }
}

class Program
{
    static void Main(string[] args)
    {
        for (int i = 1; i <= 6; i++)
        {
            string threadName = "Thread " + i;
            int secondsToWait = 2 + 2 * i;
            var t = new Thread(() => AccessDatabase(threadName, secondsToWait));
            t.Start();
        }
    }

    static SemaphoreSlim _semaphore = new SemaphoreSlim(4);

    static void AccessDatabase(string name, int seconds)
    {
        Console.WriteLine("{0} waits to access a database", name);
        _semaphore.Wait();
        Console.WriteLine("{0} was granted an access to a database", name);
        Thread.Sleep(TimeSpan.FromSeconds(seconds));
        Console.WriteLine("{0} is completed", name);
        _semaphore.Release();

    }
}

class Program
{
    static void Main(string[] args)
    {
        var t = new Thread(() => Process(10));
        t.Start();

        Console.WriteLine("Waiting for another thread to complete work");
        _workerEvent.WaitOne();
        Console.WriteLine("First operation is completed!");
        Console.WriteLine("Performing an operation on a main thread");
        Thread.Sleep(TimeSpan.FromSeconds(5));
        _mainEvent.Set();
        Console.WriteLine("Now running the second operation on a second thread");
        _workerEvent.WaitOne();
        Console.WriteLine("Second operation is completed!");

        Console.ReadKey();
    }

    private static AutoResetEvent _workerEvent = new AutoResetEvent(false);
    private static AutoResetEvent _mainEvent = new AutoResetEvent(false);

    static void Process(int seconds)
    {
        Console.WriteLine("Starting a long running work...");
        Thread.Sleep(TimeSpan.FromSeconds(seconds));
        Console.WriteLine("Work is done!");
        _workerEvent.Set();
        Console.WriteLine("Waiting for a main thread to complete its work");
        _mainEvent.WaitOne();
        Console.WriteLine("Starting second operation...");
        Thread.Sleep(TimeSpan.FromSeconds(seconds));
        Console.WriteLine("Work is done!");
        _workerEvent.Set();
    }
}

class Program
{
    static void Main(string[] args)
    {
        var t1 = new Thread(() => TravelThroughGates("Thread 1", 5));
        var t2 = new Thread(() => TravelThroughGates("Thread 2", 6));
        var t3 = new Thread(() => TravelThroughGates("Thread 3", 12));
        t1.Start();
        t2.Start();
        t3.Start();
        Thread.Sleep(TimeSpan.FromSeconds(6));
        Console.WriteLine("The gates are now open!");
        _mainEvent.Set();
        Thread.Sleep(TimeSpan.FromSeconds(2));
        _mainEvent.Reset();
        Console.WriteLine("The gates have been closed!");
        Thread.Sleep(TimeSpan.FromSeconds(10));
        Console.WriteLine("The gates are now open for the second time!");
        _mainEvent.Set();
        Thread.Sleep(TimeSpan.FromSeconds(2));
        Console.WriteLine("The gates have been closed!");
        _mainEvent.Reset();

        Console.ReadKey();
    }

    static void TravelThroughGates(string threadName, int seconds)
    {
        Console.WriteLine("{0} falls to sleep", threadName);
        Thread.Sleep(TimeSpan.FromSeconds(seconds));
        Console.WriteLine("{0} waits for the gates to open!", threadName);
        _mainEvent.Wait();
        Console.WriteLine("{0} enters the gates!", threadName);
    }

    static ManualResetEventSlim _mainEvent = new ManualResetEventSlim(false);
}

class Program
{
    static void Main(string[] args)
    {
        Console.WriteLine("Starting two operations");
        var t1 = new Thread(() => PerformOperation("Operation 1 is completed", 4));
        var t2 = new Thread(() => PerformOperation("Operation 2 is completed", 8));
        t1.Start();
        t2.Start();
        _countdown.Wait();
        Console.WriteLine("Both operations have been completed.");
        _countdown.Dispose();

        Console.ReadKey();
    }

    static CountdownEvent _countdown = new CountdownEvent(2);

    static void PerformOperation(string message, int seconds)
    {
        Thread.Sleep(TimeSpan.FromSeconds(seconds));
        Console.WriteLine(message);
        _countdown.Signal();
    }
}

class Program
{
    static void Main(string[] args)
    {
        var t1 = new Thread(() => PlayMusic("the guitarist", "play an amazing solo", 5));
        var t2 = new Thread(() => PlayMusic("the singer", "sing his song", 2));

        t1.Start();
        t2.Start();

        Console.ReadKey();
    }

    static Barrier _barrier = new Barrier(2,b => Console.WriteLine("End of phase {0}", b.CurrentPhaseNumber + 1));

    static void PlayMusic(string name, string message, int seconds)
    {
        for (int i = 1; i < 3; i++)
        {
            Console.WriteLine("----------------------------------------------");
            Thread.Sleep(TimeSpan.FromSeconds(seconds));
            Console.WriteLine("{0} starts to {1}", name, message);
            Thread.Sleep(TimeSpan.FromSeconds(seconds));
            Console.WriteLine("{0} finishes to {1}", name, message);
            _barrier.SignalAndWait();
        }
    }
}

class Program
{
    static void Main(string[] args)
    {
        new Thread(Read){ IsBackground = true }.Start();
        new Thread(Read){ IsBackground = true }.Start();
        new Thread(Read){ IsBackground = true }.Start();

        new Thread(() => Write("Thread 1")){ IsBackground = true }.Start();
        new Thread(() => Write("Thread 2")){ IsBackground = true }.Start();

        Thread.Sleep(TimeSpan.FromSeconds(30));

        Console.ReadKey();
    }

    static ReaderWriterLockSlim _rw = new ReaderWriterLockSlim();
    static Dictionary<int, int> _items = new Dictionary<int, int>();

    static void Read()
    {
        Console.WriteLine("Reading contents of a dictionary");
        while (true)
        {
            try
            {
                _rw.EnterReadLock();
                foreach (var key in _items.Keys)
                {
                    Thread.Sleep(TimeSpan.FromSeconds(0.1));
                }
            }
            finally
            {
                _rw.ExitReadLock();
            }
        }
    }

    static void Write(string threadName)
    {
        while (true)
        {
            try
            {
                int newKey = new Random().Next(250);
                _rw.EnterUpgradeableReadLock();
                if (!_items.ContainsKey(newKey))
                {
                    try
                    {
                        _rw.EnterWriteLock();
                        _items[newKey] = 1;
                        Console.WriteLine("New key {0} is added to a dictionary by a {1}", newKey, threadName);
                    }
                    finally
                    {
                        _rw.ExitWriteLock();
                    }
                }
                Thread.Sleep(TimeSpan.FromSeconds(0.1));
            }
            finally
            {
                _rw.ExitUpgradeableReadLock();
            }
        }
    }
}

class Program
{
    static void Main(string[] args)
    {
        var t1 = new Thread(UserModeWait);
        var t2 = new Thread(HybridSpinWait);

        Console.WriteLine("Running user mode waiting");
        t1.Start();
        Thread.Sleep(20);
        _isCompleted = true;
        Thread.Sleep(TimeSpan.FromSeconds(1));
        _isCompleted = false;
        Console.WriteLine("Running hybrid SpinWait construct waiting");
        t2.Start();
        Thread.Sleep(5);
        _isCompleted = true;

        Console.ReadKey();
    }

    static volatile bool _isCompleted = false;

    static void UserModeWait()
    {
        while (!_isCompleted)
        {
            Console.Write(".");
        }
        Console.WriteLine();
        Console.WriteLine("Waiting is complete");
    }

    static void HybridSpinWait()
    {
        var w = new SpinWait();
        while (!_isCompleted)
        {
            w.SpinOnce();
            Console.WriteLine(w.NextSpinWillYield);
        }
        Console.WriteLine("Waiting is complete");
    }
}

class Program
{
    static void Main(string[] args)
    {
        int threadId = 0;

        RunOnThreadPool poolDelegate = Test;

        var t = new Thread(() => Test(out threadId));
        t.Start();
        t.Join();

        Console.WriteLine("Thread id: {0}", threadId);

        IAsyncResult r = poolDelegate.BeginInvoke(out threadId, Callback, "a delegate asynchronous call");
        r.AsyncWaitHandle.WaitOne();

        string result = poolDelegate.EndInvoke(out threadId, r);
        
        Console.WriteLine("Thread pool worker thread id: {0}", threadId);
        Console.WriteLine(result);

        Thread.Sleep(TimeSpan.FromSeconds(2));

        Console.ReadKey();
    }

    private delegate string RunOnThreadPool(out int threadId);

    private static void Callback(IAsyncResult ar)
    {
        Console.WriteLine("Starting a callback...");
        Console.WriteLine("State passed to a callbak: {0}", ar.AsyncState);
        Console.WriteLine("Is thread pool thread: {0}", Thread.CurrentThread.IsThreadPoolThread);
        Console.WriteLine("Thread pool worker thread id: {0}", Thread.CurrentThread.ManagedThreadId);
    }


    private static string Test(out int threadId)
    {
        Console.WriteLine("Starting...");
        Console.WriteLine("Is thread pool thread: {0}", Thread.CurrentThread.IsThreadPoolThread);
        Thread.Sleep(TimeSpan.FromSeconds(2));
        threadId = Thread.CurrentThread.ManagedThreadId;
        return string.Format("Thread pool worker thread id was: {0}", threadId);
    }
}

class Program
{
    static void Main(string[] args)
    {
        const int x = 1;
        const int y = 2;
        const string lambdaState = "lambda state 2";

        ThreadPool.QueueUserWorkItem(AsyncOperation);
        Thread.Sleep(TimeSpan.FromSeconds(1));

        ThreadPool.QueueUserWorkItem(AsyncOperation, "async state");
        Thread.Sleep(TimeSpan.FromSeconds(1));

        ThreadPool.QueueUserWorkItem( state => {
                Console.WriteLine("Operation state: {0}", state);
                Console.WriteLine("Worker thread id: {0}", Thread.CurrentThread.ManagedThreadId);
                Thread.Sleep(TimeSpan.FromSeconds(2));
            }, "lambda state");

        ThreadPool.QueueUserWorkItem( _ =>
        {
            Console.WriteLine("Operation state: {0}, {1}", x+y, lambdaState);
            Console.WriteLine("Worker thread id: {0}", Thread.CurrentThread.ManagedThreadId);
            Thread.Sleep(TimeSpan.FromSeconds(2));
        }, "lambda state");

        Thread.Sleep(TimeSpan.FromSeconds(2));

        Console.ReadKey();
    }

    private static void AsyncOperation(object state)
    {
        Console.WriteLine("Operation state: {0}", state ?? "(null)");
        Console.WriteLine("Worker thread id: {0}", Thread.CurrentThread.ManagedThreadId);
        Thread.Sleep(TimeSpan.FromSeconds(2));
    }
}

class Program
{
    static void Main(string[] args)
    {
        const int numberOfOperations = 500;
        var sw = new Stopwatch();
        sw.Start();
        UseThreads(numberOfOperations);
        sw.Stop();
        Console.WriteLine("Execution time using threads: {0}", sw.ElapsedMilliseconds);

        sw.Reset();
        sw.Start();
        UseThreadPool(numberOfOperations);
        sw.Stop();
        Console.WriteLine("Execution time using threads: {0}", sw.ElapsedMilliseconds);

        Console.ReadKey();
    }

    static void UseThreads(int numberOfOperations)
    {
        using (var countdown = new CountdownEvent(numberOfOperations))
        {
            Console.WriteLine("Scheduling work by creating threads");
            for (int i = 0; i < numberOfOperations; i++)
            {
                var thread = new Thread(() => {
                    Console.Write("{0},", Thread.CurrentThread.ManagedThreadId);
                    Thread.Sleep(TimeSpan.FromSeconds(0.1));
                    countdown.Signal();
                });
                thread.Start();
            }
            countdown.Wait();
            Console.WriteLine();
        }
    }

    static void UseThreadPool(int numberOfOperations)
    {
        using (var countdown = new CountdownEvent(numberOfOperations))
        {
            Console.WriteLine("Starting work on a threadpool");
            for (int i = 0; i < numberOfOperations; i++)
            {
                ThreadPool.QueueUserWorkItem( _ => {
                    Console.Write("{0},", Thread.CurrentThread.ManagedThreadId);
                    Thread.Sleep(TimeSpan.FromSeconds(0.1));
                    countdown.Signal();
                });
            }
            countdown.Wait();
            Console.WriteLine();
        }
    }
}

class Program
{
    static void Main(string[] args)
    {
        using (var cts = new CancellationTokenSource())
        {
            CancellationToken token = cts.Token;
            ThreadPool.QueueUserWorkItem(_ => AsyncOperation1(token));
            Thread.Sleep(TimeSpan.FromSeconds(2));
            cts.Cancel();
        }

        using (var cts = new CancellationTokenSource())
        {
            CancellationToken token = cts.Token;
            ThreadPool.QueueUserWorkItem(_ => AsyncOperation2(token));
            Thread.Sleep(TimeSpan.FromSeconds(2));
            cts.Cancel();
        }

        using (var cts = new CancellationTokenSource())
        {
            CancellationToken token = cts.Token;
            ThreadPool.QueueUserWorkItem(_ => AsyncOperation3(token));
            Thread.Sleep(TimeSpan.FromSeconds(2));
            cts.Cancel();
        }

        Thread.Sleep(TimeSpan.FromSeconds(2));
    }

    static void AsyncOperation1(CancellationToken token)
    {
        Console.WriteLine("Starting the first task");
        for (int i = 0; i < 5; i++)
        {
            if (token.IsCancellationRequested)
            {
                Console.WriteLine("The first task has been canceled.");
                return;
            }
            Thread.Sleep(TimeSpan.FromSeconds(1));
        }
        Console.WriteLine("The first task has completed succesfully");
    }

    static void AsyncOperation2(CancellationToken token)
    {
        try
        {
            Console.WriteLine("Starting the second task");

            for (int i = 0; i < 5; i++)
            {
                token.ThrowIfCancellationRequested();
                Thread.Sleep(TimeSpan.FromSeconds(1));
            }
            Console.WriteLine("The second task has completed succesfully");
        }
        catch (OperationCanceledException)
        {
            Console.WriteLine("The second task has been canceled.");
        }
    }

    private static void AsyncOperation3(CancellationToken token)
    {
        bool cancellationFlag = false;
        token.Register(() => cancellationFlag = true);
        Console.WriteLine("Starting the third task");
        for (int i = 0; i < 5; i++)
        {
            if (cancellationFlag)
            {
                Console.WriteLine("The third task has been canceled.");
                return;
            }
            Thread.Sleep(TimeSpan.FromSeconds(1));
        }
        Console.WriteLine("The third task has completed succesfully");
    }
}

class Program
{
    static void Main(string[] args)
    {
        RunOperations(TimeSpan.FromSeconds(5));
        RunOperations(TimeSpan.FromSeconds(7));
    }

    static void RunOperations(TimeSpan workerOperationTimeout)
    {
        using (var evt = new ManualResetEvent(false))
        using (var cts = new CancellationTokenSource())
        {
            Console.WriteLine("Registering timeout operations...");
            var worker = ThreadPool.RegisterWaitForSingleObject(evt,
                (state, isTimedOut) => WorkerOperationWait(cts, isTimedOut), null, workerOperationTimeout, true);

            Console.WriteLine("Starting long running operation...");

            ThreadPool.QueueUserWorkItem(_ => WorkerOperation(cts.Token, evt));

            Thread.Sleep(workerOperationTimeout.Add(TimeSpan.FromSeconds(2)));
            worker.Unregister(evt);
        }
    }

    static void WorkerOperation(CancellationToken token, ManualResetEvent evt)
    {
        for(int i = 0; i < 6; i++)
        {
            if (token.IsCancellationRequested)
            {
                return;
            }
            Thread.Sleep(TimeSpan.FromSeconds(1));
        }
        evt.Set();
    }

    static void WorkerOperationWait(CancellationTokenSource cts, bool isTimedOut)
    {
        if (isTimedOut)
        {
            cts.Cancel();
            Console.WriteLine("Worker operation timed out and was canceled.");
        }
        else
        {
            Console.WriteLine("Worker operation succeded.");
        }
    }
}

    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("Press ‘Enter‘ to stop the timer...");
            DateTime start = DateTime.Now;
            _timer = new Timer(_ => TimerOperation(start), null, TimeSpan.FromSeconds(1), TimeSpan.FromSeconds(2));

            Thread.Sleep(TimeSpan.FromSeconds(6));

            _timer.Change(TimeSpan.FromSeconds(1), TimeSpan.FromSeconds(4));

            Console.ReadLine();

            _timer.Dispose();

            Console.ReadKey();
        }

        static Timer _timer;

        static void TimerOperation(DateTime start)
        {
            TimeSpan elapsed = DateTime.Now - start;
            Console.WriteLine("{0} seconds from {1}. Timer thread pool thread id: {2}", elapsed.Seconds, start,Thread.CurrentThread.ManagedThreadId);
        }
    }

class Program
{
    static void Main(string[] args)
    {
        var bw = new BackgroundWorker();
        bw.WorkerReportsProgress = true;
        bw.WorkerSupportsCancellation = true;

        bw.DoWork += Worker_DoWork;
        bw.ProgressChanged += Worker_ProgressChanged;
        bw.RunWorkerCompleted += Worker_Completed;

        bw.RunWorkerAsync();

        Console.WriteLine("Press C to cancel work");
        do
        {
            if (Console.ReadKey(true).KeyChar == ‘C‘)
            {
                bw.CancelAsync();
            }
            
        }
        while(bw.IsBusy);
    }

    static void Worker_DoWork(object sender, DoWorkEventArgs e)
    {
        Console.WriteLine("DoWork thread pool thread id: {0}", Thread.CurrentThread.ManagedThreadId);
        var bw = (BackgroundWorker) sender;
        for (int i = 1; i <= 100; i++)
        {

            if (bw.CancellationPending)
            {
                e.Cancel = true;
                return;
            }

            if (i%10 == 0)
            {
                bw.ReportProgress(i);
            }

            Thread.Sleep(TimeSpan.FromSeconds(0.1));
        }
        e.Result = 42;
    }

    static void Worker_ProgressChanged(object sender, ProgressChangedEventArgs e)
    {
        Console.WriteLine("{0}% completed. Progress thread pool thread id: {1}", e.ProgressPercentage,
            Thread.CurrentThread.ManagedThreadId);
    }

    static void Worker_Completed(object sender, RunWorkerCompletedEventArgs e)
    {
        Console.WriteLine("Completed thread pool thread id: {0}", Thread.CurrentThread.ManagedThreadId);
        if (e.Error != null)
        {
            Console.WriteLine("Exception {0} has occured.", e.Error.Message);
        }
        else if (e.Cancelled)
        {
            Console.WriteLine("Operation has been canceled.");
        }
        else
        {
            Console.WriteLine("The answer is: {0}", e.Result);
        }
    }
}

class Program
{
    static void Main(string[] args)
    {
        var t1 = new Task(() => TaskMethod("Task 1"));
        var t2 = new Task(() => TaskMethod("Task 2"));
        t2.Start();
        t1.Start();
        Task.Run(() => TaskMethod("Task 3"));
        Task.Factory.StartNew(() => TaskMethod("Task 4"));
        Task.Factory.StartNew(() => TaskMethod("Task 5"), TaskCreationOptions.LongRunning);
        Thread.Sleep(TimeSpan.FromSeconds(1));

        Console.ReadKey();
    }

    static void TaskMethod(string name)
    {
        Console.WriteLine("Task {0} is running on a thread id {1}. Is thread pool thread: {2}",
            name, Thread.CurrentThread.ManagedThreadId, Thread.CurrentThread.IsThreadPoolThread);
    }
}

class Program
{
    static void Main(string[] args)
    {
        TaskMethod("Main Thread Task");
        Task<int> task = CreateTask("Task 1");
        task.Start();
        int result = task.Result;
        Console.WriteLine("Result is: {0}", result);

        task = CreateTask("Task 2");
        task.RunSynchronously();
        result = task.Result;
        Console.WriteLine("Result is: {0}", result);

        task = CreateTask("Task 3");
        Console.WriteLine(task.Status);
        task.Start();

        while (!task.IsCompleted)
        {
            Console.WriteLine(task.Status);
            Thread.Sleep(TimeSpan.FromSeconds(0.5));
        } 
        
        Console.WriteLine(task.Status);
        result = task.Result;
        Console.WriteLine("Result is: {0}", result);

        Console.ReadKey();
    }

    static Task<int> CreateTask(string name)
    {
        return new Task<int>(() => TaskMethod(name));
    }

    static int TaskMethod(string name)
    {
        Console.WriteLine("Task {0} is running on a thread id {1}. Is thread pool thread: {2}",
            name, Thread.CurrentThread.ManagedThreadId, Thread.CurrentThread.IsThreadPoolThread);
        Thread.Sleep(TimeSpan.FromSeconds(2));
        return 42;
    }
}

class Program
{
    static void Main(string[] args)
    {
        var firstTask = new Task<int>(() => TaskMethod("First Task", 3));
        var secondTask = new Task<int>(() => TaskMethod("Second Task", 2));

        firstTask.ContinueWith(
            t => Console.WriteLine("The first answer is {0}. Thread id {1}, is thread pool thread: {2}",
                t.Result, Thread.CurrentThread.ManagedThreadId, Thread.CurrentThread.IsThreadPoolThread),
            TaskContinuationOptions.OnlyOnRanToCompletion);

        firstTask.Start();
        secondTask.Start();

        Thread.Sleep(TimeSpan.FromSeconds(4));

        Task continuation = secondTask.ContinueWith(
            t => Console.WriteLine("The second answer is {0}. Thread id {1}, is thread pool thread: {2}",
                t.Result, Thread.CurrentThread.ManagedThreadId, Thread.CurrentThread.IsThreadPoolThread),
            TaskContinuationOptions.OnlyOnRanToCompletion | TaskContinuationOptions.ExecuteSynchronously);

        continuation.GetAwaiter().OnCompleted(
            () => Console.WriteLine("Continuation Task Completed! Thread id {0}, is thread pool thread: {1}",
                Thread.CurrentThread.ManagedThreadId, Thread.CurrentThread.IsThreadPoolThread));

        Thread.Sleep(TimeSpan.FromSeconds(2));
        Console.WriteLine();

        firstTask = new Task<int>(() =>
        {
            var innerTask = Task.Factory.StartNew(() => TaskMethod("Second Task", 5), TaskCreationOptions.AttachedToParent);
            innerTask.ContinueWith(t => TaskMethod("Third Task", 2), TaskContinuationOptions.AttachedToParent);
            return TaskMethod("First Task", 2);
        });

        firstTask.Start();

        while (!firstTask.IsCompleted)
        {
            Console.WriteLine(firstTask.Status);
            Thread.Sleep(TimeSpan.FromSeconds(0.5));
        }
        Console.WriteLine(firstTask.Status);

        Thread.Sleep(TimeSpan.FromSeconds(10));
    }

    static int TaskMethod(string name, int seconds)
    {
        Console.WriteLine("Task {0} is running on a thread id {1}. Is thread pool thread: {2}",
            name, Thread.CurrentThread.ManagedThreadId, Thread.CurrentThread.IsThreadPoolThread);
        Thread.Sleep(TimeSpan.FromSeconds(seconds));
        return 42 * seconds;
    }
}

class Program
{
    private static void Main(string[] args)
    {
        int threadId;
        AsynchronousTask d = Test;
        IncompatibleAsynchronousTask e = Test;

        Console.WriteLine("Option 1");
        Task<string> task = Task<string>.Factory.FromAsync(
            d.BeginInvoke("AsyncTaskThread", Callback, "a delegate asynchronous call"), d.EndInvoke);

        task.ContinueWith(t => Console.WriteLine("Callback is finished, now running a continuation! Result: {0}",
            t.Result));

        while (!task.IsCompleted)
        {
            Console.WriteLine(task.Status);
            Thread.Sleep(TimeSpan.FromSeconds(0.5));
        }
        Console.WriteLine(task.Status);
        Thread.Sleep(TimeSpan.FromSeconds(1));

        Console.WriteLine("----------------------------------------------");
        Console.WriteLine();
        Console.WriteLine("Option 2");

        task = Task<string>.Factory.FromAsync(
            d.BeginInvoke, d.EndInvoke, "AsyncTaskThread", "a delegate asynchronous call");
        task.ContinueWith(t => Console.WriteLine("Task is completed, now running a continuation! Result: {0}",
            t.Result));
        while (!task.IsCompleted)
        {
            Console.WriteLine(task.Status);
            Thread.Sleep(TimeSpan.FromSeconds(0.5));
        }
        Console.WriteLine(task.Status);
        Thread.Sleep(TimeSpan.FromSeconds(1));

        Console.WriteLine("----------------------------------------------");
        Console.WriteLine();
        Console.WriteLine("Option 3");

        IAsyncResult ar = e.BeginInvoke(out threadId, Callback, "a delegate asynchronous call");
        task = Task<string>.Factory.FromAsync(ar, _ => e.EndInvoke(out threadId, ar));
        task.ContinueWith(t => 
            Console.WriteLine("Task is completed, now running a continuation! Result: {0}, ThreadId: {1}",
                t.Result, threadId));

        while (!task.IsCompleted)
        {
            Console.WriteLine(task.Status);
            Thread.Sleep(TimeSpan.FromSeconds(0.5));
        }
        Console.WriteLine(task.Status);

        Thread.Sleep(TimeSpan.FromSeconds(1));

        Console.ReadKey();
    }

    private delegate string AsynchronousTask(string threadName);
    private delegate string IncompatibleAsynchronousTask(out int threadId);

    private static void Callback(IAsyncResult ar)
    {
        Console.WriteLine("Starting a callback...");
        Console.WriteLine("State passed to a callbak: {0}", ar.AsyncState);
        Console.WriteLine("Is thread pool thread: {0}", Thread.CurrentThread.IsThreadPoolThread);
        Console.WriteLine("Thread pool worker thread id: {0}", Thread.CurrentThread.ManagedThreadId);
    }

    private static string Test(string threadName)
    {
        Console.WriteLine("Starting...");
        Console.WriteLine("Is thread pool thread: {0}", Thread.CurrentThread.IsThreadPoolThread);
        Thread.Sleep(TimeSpan.FromSeconds(2));
        Thread.CurrentThread.Name = threadName;
        return string.Format("Thread name: {0}", Thread.CurrentThread.Name);
    }

    private static string Test(out int threadId)
    {
        Console.WriteLine("Starting...");
        Console.WriteLine("Is thread pool thread: {0}", Thread.CurrentThread.IsThreadPoolThread);
        Thread.Sleep(TimeSpan.FromSeconds(2));
        threadId = Thread.CurrentThread.ManagedThreadId;
        return string.Format("Thread pool worker thread id was: {0}", threadId);
    }
}

class Program
{
    static void Main(string[] args)
    {
        var tcs = new TaskCompletionSource<int>();

        var worker = new BackgroundWorker();
        worker.DoWork += (sender, eventArgs) =>
        {
            eventArgs.Result = TaskMethod("Background worker", 5);
        };

        worker.RunWorkerCompleted += (sender, eventArgs) =>
        {
            if (eventArgs.Error != null)
            {
                tcs.SetException(eventArgs.Error);
            }
            else if (eventArgs.Cancelled)
            {
                tcs.SetCanceled();
            }
            else
            {
                tcs.SetResult((int)eventArgs.Result);
            }
        };

        worker.RunWorkerAsync();

        int result = tcs.Task.Result;

        Console.WriteLine("Result is: {0}", result);
    }

    static int TaskMethod(string name, int seconds)
    {
        Console.WriteLine("Task {0} is running on a thread id {1}. Is thread pool thread: {2}",
            name, Thread.CurrentThread.ManagedThreadId, Thread.CurrentThread.IsThreadPoolThread);
        Thread.Sleep(TimeSpan.FromSeconds(seconds));
        return 42 * seconds;
    }
}

class Program
{
    private static void Main(string[] args)
    {
        var cts = new CancellationTokenSource();
        var longTask = new Task<int>(() => TaskMethod("Task 1", 10, cts.Token), cts.Token);
        Console.WriteLine(longTask.Status);
        cts.Cancel();
        Console.WriteLine(longTask.Status);
        Console.WriteLine("First task has been cancelled before execution");
        cts = new CancellationTokenSource();
        longTask = new Task<int>(() => TaskMethod("Task 2", 10, cts.Token), cts.Token);
        longTask.Start();
        for (int i = 0; i < 5; i++ )
        {
            Thread.Sleep(TimeSpan.FromSeconds(0.5));
            Console.WriteLine(longTask.Status);
        }
        cts.Cancel();
        for (int i = 0; i < 5; i++)
        {
            Thread.Sleep(TimeSpan.FromSeconds(0.5));
            Console.WriteLine(longTask.Status);
        }

        Console.WriteLine("A task has been completed with result {0}.", longTask.Result);

        Console.ReadKey();
    }

    private static int TaskMethod(string name, int seconds, CancellationToken token)
    {
        Console.WriteLine("Task {0} is running on a thread id {1}. Is thread pool thread: {2}",
            name, Thread.CurrentThread.ManagedThreadId, Thread.CurrentThread.IsThreadPoolThread);
        for (int i = 0; i < seconds; i ++)
        {
            Thread.Sleep(TimeSpan.FromSeconds(1));
            if (token.IsCancellationRequested) return -1;
        }
        return 42*seconds;
    }
}

class Program
{
    static void Main(string[] args)
    {
        Task<int> task;
        try
        {
            task = Task.Run(() => TaskMethod("Task 1", 2));
            int result = task.Result;
            Console.WriteLine("Result: {0}", result);
        }
        catch (Exception ex)
        {
            Console.WriteLine("Exception caught: {0}", ex);
        }
        Console.WriteLine("----------------------------------------------");
        Console.WriteLine();

        try
        {
            task = Task.Run(() => TaskMethod("Task 2", 2));
            int result = task.GetAwaiter().GetResult();
            Console.WriteLine("Result: {0}", result);
        }
        catch (Exception ex)
        {
            Console.WriteLine("Exception caught: {0}", ex);
        }
        Console.WriteLine("----------------------------------------------");
        Console.WriteLine();

        var t1 = new Task<int>(() => TaskMethod("Task 3", 3));
        var t2 = new Task<int>(() => TaskMethod("Task 4", 2));
        var complexTask = Task.WhenAll(t1, t2);
        var exceptionHandler = complexTask.ContinueWith(t => 
                Console.WriteLine("Exception caught: {0}", t.Exception), 
                TaskContinuationOptions.OnlyOnFaulted
            );
        t1.Start();
        t2.Start();

        Thread.Sleep(TimeSpan.FromSeconds(5));

        Console.ReadKey();
    }

    static int TaskMethod(string name, int seconds)
    {
        Console.WriteLine("Task {0} is running on a thread id {1}. Is thread pool thread: {2}",
            name, Thread.CurrentThread.ManagedThreadId, Thread.CurrentThread.IsThreadPoolThread);
        Thread.Sleep(TimeSpan.FromSeconds(seconds));
        throw new Exception("Boom!");
        return 42 * seconds;
    }
}

class Program
{
    static void Main(string[] args)
    {
        var firstTask = new Task<int>(() => TaskMethod("First Task", 3));
        var secondTask = new Task<int>(() => TaskMethod("Second Task", 2));
        var whenAllTask = Task.WhenAll(firstTask, secondTask);

        whenAllTask.ContinueWith(t =>
            Console.WriteLine("The first answer is {0}, the second is {1}", t.Result[0], t.Result[1]),
            TaskContinuationOptions.OnlyOnRanToCompletion
            );

        firstTask.Start();
        secondTask.Start();

        Thread.Sleep(TimeSpan.FromSeconds(4));

        var tasks = new List<Task<int>>();
        for (int i = 1; i < 4; i++)
        {
            int counter = i;
            var task = new Task<int>(() => TaskMethod(string.Format("Task {0}", counter), counter));
            tasks.Add(task);
            task.Start();
        }

        while (tasks.Count > 0)
        {
            var completedTask = Task.WhenAny(tasks).Result;
            tasks.Remove(completedTask);
            Console.WriteLine("A task has been completed with result {0}.", completedTask.Result);
        }

        Thread.Sleep(TimeSpan.FromSeconds(1));

        Console.ReadKey();
    }

    static int TaskMethod(string name, int seconds)
    {
        Console.WriteLine("Task {0} is running on a thread id {1}. Is thread pool thread: {2}",
            name, Thread.CurrentThread.ManagedThreadId, Thread.CurrentThread.IsThreadPoolThread);
        Thread.Sleep(TimeSpan.FromSeconds(seconds));
        return 42 * seconds;
    }
}

<TextBlock Name="ContentTextBlock" HorizontalAlignment="Left" Margin="44,134,0,0" VerticalAlignment="Top" Width="425" Height="40"/>
<Button Content="Sync" HorizontalAlignment="Left" Margin="45,190,0,0" VerticalAlignment="Top" Width="75" Click="ButtonSync_Click"/>
<Button Content="Async" HorizontalAlignment="Left" Margin="165,190,0,0" VerticalAlignment="Top" Width="75" Click="ButtonAsync_Click"/>
<Button Content="Async OK" HorizontalAlignment="Left" Margin="285,190,0,0" VerticalAlignment="Top" Width="75" Click="ButtonAsyncOK_Click"/>

using System;
using System.Threading;
using System.Threading.Tasks;
using System.Windows;
using System.Windows.Input;

void ButtonSync_Click(object sender, RoutedEventArgs e)
{
    ContentTextBlock.Text = string.Empty;
    try
    {
        //string result = TaskMethod(TaskScheduler.FromCurrentSynchronizationContext()).Result;
        string result = TaskMethod().Result;
        ContentTextBlock.Text = result;
    }
    catch (Exception ex)
    {
        ContentTextBlock.Text = ex.InnerException.Message;
    }
}

void ButtonAsync_Click(object sender, RoutedEventArgs e)
{
    ContentTextBlock.Text = string.Empty;
    Mouse.OverrideCursor = Cursors.Wait;
    Task<string> task = TaskMethod();
    task.ContinueWith(t => {
            ContentTextBlock.Text = t.Exception.InnerException.Message;
            Mouse.OverrideCursor = null;
        }, 
        CancellationToken.None,
        TaskContinuationOptions.OnlyOnFaulted,
        TaskScheduler.FromCurrentSynchronizationContext());
}

void ButtonAsyncOK_Click(object sender, RoutedEventArgs e)
{
    ContentTextBlock.Text = string.Empty;
    Mouse.OverrideCursor = Cursors.Wait;
    Task<string> task = TaskMethod(TaskScheduler.FromCurrentSynchronizationContext());
    task.ContinueWith(t => Mouse.OverrideCursor = null,
        CancellationToken.None,
        TaskContinuationOptions.None,
        TaskScheduler.FromCurrentSynchronizationContext());
}

Task<string> TaskMethod()
{
    return TaskMethod(TaskScheduler.Default);
}

Task<string> TaskMethod(TaskScheduler scheduler)
{
    Task delay = Task.Delay(TimeSpan.FromSeconds(5));

    return delay.ContinueWith(t =>
    {
        string str = string.Format("Task is running on a thread id {0}. Is thread pool thread: {1}",
                Thread.CurrentThread.ManagedThreadId, Thread.CurrentThread.IsThreadPoolThread);
        ContentTextBlock.Text = str;
        return str;
    }, scheduler);
}

class Program
{
    static void Main(string[] args)
    {
        Task t = AsynchronyWithTPL();
        t.Wait();

        t = AsynchronyWithAwait();
        t.Wait();

        Console.ReadKey();
    }

    static Task AsynchronyWithTPL()
    {
        Task<string> t = GetInfoAsync("Task 1");
        Task t2 = t.ContinueWith(task => Console.WriteLine(t.Result),
            TaskContinuationOptions.NotOnFaulted);
        Task t3 = t.ContinueWith(task => Console.WriteLine(t.Exception.InnerException),
            TaskContinuationOptions.OnlyOnFaulted);

        return Task.WhenAny(t2, t3);
    }

    async static Task AsynchronyWithAwait()
    {
        try
        {
            string result = await GetInfoAsync("Task 2");
            Console.WriteLine(result);
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex);
        }
    }

    async static Task<string> GetInfoAsync(string name)
    {
        await Task.Delay(TimeSpan.FromSeconds(2));
        //throw new Exception("Boom!");
        return string.Format("Task {0} is running on a thread id {1}. Is thread pool thread: {2}",
            name, Thread.CurrentThread.ManagedThreadId, Thread.CurrentThread.IsThreadPoolThread);
    }
}

class Program
{
    static void Main(string[] args)
    {
        Task t = AsynchronousProcessing();
        t.Wait();

        Console.ReadKey();
    }

    async static Task AsynchronousProcessing()
    {
        Func<string, Task<string>> asyncLambda = async name => {
            await Task.Delay(TimeSpan.FromSeconds(2));
            return string.Format("Task {0} is running on a thread id {1}. Is thread pool thread: {2}",
                name, Thread.CurrentThread.ManagedThreadId, Thread.CurrentThread.IsThreadPoolThread);
        };

        string result = await asyncLambda("async lambda");

        Console.WriteLine(result);
    }
}

class Program
{
    static void Main(string[] args)
    {
        Task t = AsynchronyWithTPL();
        t.Wait();

        t = AsynchronyWithAwait();
        t.Wait();

        Console.ReadKey();
    }

    static Task AsynchronyWithTPL()
    {
        var containerTask = new Task(() => { 
            Task<string> t = GetInfoAsync("TPL 1");
            t.ContinueWith(task => {
                Console.WriteLine(t.Result);
                Task<string> t2 = GetInfoAsync("TPL 2");
                t2.ContinueWith(innerTask => Console.WriteLine(innerTask.Result),
                    TaskContinuationOptions.NotOnFaulted | TaskContinuationOptions.AttachedToParent);
                t2.ContinueWith(innerTask => Console.WriteLine(innerTask.Exception.InnerException),
                    TaskContinuationOptions.OnlyOnFaulted | TaskContinuationOptions.AttachedToParent);
                },
                TaskContinuationOptions.NotOnFaulted | TaskContinuationOptions.AttachedToParent);

            t.ContinueWith(task => Console.WriteLine(t.Exception.InnerException),
                TaskContinuationOptions.OnlyOnFaulted | TaskContinuationOptions.AttachedToParent);
        });

        containerTask.Start();
        return containerTask;
    }

    async static Task AsynchronyWithAwait()
    {
        try
        {
            string result = await GetInfoAsync("Async 1");
            Console.WriteLine(result);
            result = await GetInfoAsync("Async 2");
            Console.WriteLine(result);
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex);
        }
    }

    async static Task<string> GetInfoAsync(string name)
    {
        Console.WriteLine("Task {0} started!", name);
        await Task.Delay(TimeSpan.FromSeconds(2));
        if(name == "TPL 2")
            throw new Exception("Boom!");
        return string.Format("Task {0} is running on a thread id {1}. Is thread pool thread: {2}",
            name, Thread.CurrentThread.ManagedThreadId, Thread.CurrentThread.IsThreadPoolThread);
    }
}

class Program
{
    static void Main(string[] args)
    {
        Task t = AsynchronousProcessing();
        t.Wait();
    }

    async static Task AsynchronousProcessing()
    {
        Task<string> t1 = GetInfoAsync("Task 1", 3);
        Task<string> t2 = GetInfoAsync("Task 2", 5);

        string[] results = await Task.WhenAll(t1, t2);
        foreach (string result in results)
        {
            Console.WriteLine(result);
        }

        Console.ReadKey();
    }

    async static Task<string> GetInfoAsync(string name, int seconds)
    {
        await Task.Delay(TimeSpan.FromSeconds(seconds));
        //await Task.Run(() => Thread.Sleep(TimeSpan.FromSeconds(seconds)));
        return string.Format("Task {0} is running on a thread id {1}. Is thread pool thread: {2}",
            name, Thread.CurrentThread.ManagedThreadId, Thread.CurrentThread.IsThreadPoolThread);
    }
}

class Program
{
    static void Main(string[] args)
    {
        Task t = AsynchronousProcessing();
        t.Wait();
    }

    async static Task AsynchronousProcessing()
    {
        Console.WriteLine("1. Single exception");

        try
        {
            string result = await GetInfoAsync("Task 1", 2);
            Console.WriteLine(result);
        }
        catch (Exception ex)
        {
            Console.WriteLine("Exception details: {0}", ex);
        }

        Console.WriteLine();
        Console.WriteLine("2. Multiple exceptions");

        Task<string> t1 = GetInfoAsync("Task 1", 3);
        Task<string> t2 = GetInfoAsync("Task 2", 2);
        try
        {
            string[] results = await Task.WhenAll(t1, t2);
            Console.WriteLine(results.Length);
        }
        catch (Exception ex)
        {
            Console.WriteLine("Exception details: {0}", ex);
        }

        Console.WriteLine();
        Console.WriteLine("2. Multiple exceptions with AggregateException");

        t1 = GetInfoAsync("Task 1", 3);
        t2 = GetInfoAsync("Task 2", 2);
        Task<string[]> t3 = Task.WhenAll(t1, t2);
        try
        {
            string[] results = await t3;
            Console.WriteLine(results.Length);
        }
        catch
        {
            var ae = t3.Exception.Flatten();
            var exceptions = ae.InnerExceptions;
            Console.WriteLine("Exceptions caught: {0}", exceptions.Count);
            foreach (var e in exceptions)
            {
                Console.WriteLine("Exception details: {0}", e);
                Console.WriteLine();
            }
        }

        Console.ReadKey();
    }

    async static Task<string> GetInfoAsync(string name, int seconds)
    {
        await Task.Delay(TimeSpan.FromSeconds(seconds));
        throw new Exception(string.Format("Boom from {0}!", name));
    }
}

class Program
{
    [STAThread]
    static void Main(string[] args)
    {
        var app = new Application();
        var win = new Window();
        var panel = new StackPanel();
        var button = new Button();
        _label = new Label();
        _label.FontSize = 32;
        _label.Height = 200;
        button.Height = 100;
        button.FontSize = 32;
        button.Content = new TextBlock { Text = "Start asynchronous operations" };
        button.Click += Click;
        panel.Children.Add(_label);
        panel.Children.Add(button);
        win.Content = panel;
        app.Run(win);

        Console.ReadLine();
    }

    async static void Click(object sender, EventArgs e)
    {
        _label.Content = new TextBlock { Text = "Calculating..." };
        TimeSpan resultWithContext = await Test();
        TimeSpan resultNoContext = await TestNoContext();
        //TimeSpan resultNoContext = await TestNoContext().ConfigureAwait(false);
        var sb = new StringBuilder();
        sb.AppendLine(string.Format("With the context: {0}", resultWithContext));
        sb.AppendLine(string.Format("Without the context: {0}", resultNoContext));
        sb.AppendLine(string.Format("Ratio: {0:0.00}",
            resultWithContext.TotalMilliseconds / resultNoContext.TotalMilliseconds));
        _label.Content = new TextBlock { Text = sb.ToString() };
    }

    async static Task<TimeSpan> Test()
    {
        const int iterationsNumber = 100000;
        var sw = new Stopwatch();
        sw.Start();
        for (int i = 0; i < iterationsNumber; i++)
        {
            var t = Task.Run(() => { });
            await t;
        }
        sw.Stop();
        return sw.Elapsed;
    }

    async static Task<TimeSpan> TestNoContext()
    {
        const int iterationsNumber = 100000;
        var sw = new Stopwatch();
        sw.Start();
        for (int i = 0; i < iterationsNumber; i++)
        {
            var t = Task.Run(() => { });
            await t.ConfigureAwait(
                continueOnCapturedContext: false);
        }
        sw.Stop();
        return sw.Elapsed;
    }

    private static Label _label;
}

class Program
{
    static void Main(string[] args)
    {
        Task t = AsyncTask();
        t.Wait();

        AsyncVoid();
        Thread.Sleep(TimeSpan.FromSeconds(3));

        t = AsyncTaskWithErrors();
        while(!t.IsFaulted)
        {
            Thread.Sleep(TimeSpan.FromSeconds(1));
        }
        Console.WriteLine(t.Exception);

        //try
        //{
        //    AsyncVoidWithErrors();
        //    Thread.Sleep(TimeSpan.FromSeconds(3));
        //}
        //catch (Exception ex)
        //{
        //    Console.WriteLine(ex);
        //}

        int[] numbers = new[] {1, 2, 3, 4, 5};
        Array.ForEach(numbers, async number => {
            await Task.Delay(TimeSpan.FromSeconds(1));
            if (number == 3) throw new Exception("Boom!");
            Console.WriteLine(number);
        });

        Console.ReadLine();
    }

    async static Task AsyncTaskWithErrors()
    {
        string result = await GetInfoAsync("AsyncTaskException", 2);
        Console.WriteLine(result);
    }

    async static void AsyncVoidWithErrors()
    {
        string result = await GetInfoAsync("AsyncVoidException", 2);
        Console.WriteLine(result);
    }

    async static Task AsyncTask()
    {
        string result = await GetInfoAsync("AsyncTask", 2);
        Console.WriteLine(result);
    }

    private static async void AsyncVoid()
    {
        string result = await GetInfoAsync("AsyncVoid", 2);
        Console.WriteLine(result);
    }

    async static Task<string> GetInfoAsync(string name, int seconds)
    {
        await Task.Delay(TimeSpan.FromSeconds(seconds));
        if(name.Contains("Exception"))
            throw new Exception(string.Format("Boom from {0}!", name));
        return string.Format("Task {0} is running on a thread id {1}. Is thread pool thread: {2}",
            name, Thread.CurrentThread.ManagedThreadId, Thread.CurrentThread.IsThreadPoolThread);
    }
}

class Program
{
    static void Main(string[] args)
    {
        Task t = AsynchronousProcessing();
        t.Wait();
        Console.ReadKey();
    }

    async static Task AsynchronousProcessing()
    {
        var sync = new CustomAwaitable(true);
        string result = await sync;
        Console.WriteLine(result);

        var async = new CustomAwaitable(false);
        result = await async;

        Console.WriteLine(result);
    }

    class CustomAwaitable
    {
        public CustomAwaitable(bool completeSynchronously)
        {
            _completeSynchronously = completeSynchronously;
        }

        public CustomAwaiter GetAwaiter()
        {
            return new CustomAwaiter(_completeSynchronously);
        }

        private readonly bool _completeSynchronously;
    }

    class CustomAwaiter : INotifyCompletion
    {
        private string _result = "Completed synchronously";
        private readonly bool _completeSynchronously;

        public bool IsCompleted { get { return _completeSynchronously; } }

        public CustomAwaiter(bool completeSynchronously)
        {
            _completeSynchronously = completeSynchronously;
        }

        public string GetResult()
        {
            return _result;
        }

        public void OnCompleted(Action continuation)
        {
            ThreadPool.QueueUserWorkItem( state => {
                Thread.Sleep(TimeSpan.FromSeconds(1));
                _result = GetInfo();
                if (continuation != null) continuation();
            });
        }

        private string GetInfo()
        {
            return string.Format("Task is running on a thread id {0}. Is thread pool thread: {1}",
                Thread.CurrentThread.ManagedThreadId, Thread.CurrentThread.IsThreadPoolThread);
        }
    }
}

class Program
{
    static void Main(string[] args)
    {
        Task t = AsynchronousProcessing();
        t.Wait();
        Console.ReadKey();
    }

    async static Task AsynchronousProcessing()
    {
        string result = await GetDynamicAwaitableObject(true);
        Console.WriteLine(result);

        result = await GetDynamicAwaitableObject(false);
        Console.WriteLine(result);
    }

    static dynamic GetDynamicAwaitableObject(bool completeSynchronously)
    {
        dynamic result = new ExpandoObject();
        dynamic awaiter = new ExpandoObject();

        awaiter.Message = "Completed synchronously";
        awaiter.IsCompleted = completeSynchronously;
        awaiter.GetResult = (Func<string>)(() => awaiter.Message);

        awaiter.OnCompleted = (Action<Action>) ( callback => 
            ThreadPool.QueueUserWorkItem(state => {
                Thread.Sleep(TimeSpan.FromSeconds(1));
                awaiter.Message = GetInfo();
                if (callback != null) callback();
            })
        );

        IAwaiter<string> proxy = Impromptu.ActLike(awaiter);

        result.GetAwaiter = (Func<dynamic>) ( () => proxy );

        return result;
    }

    static string GetInfo()
    {
        return string.Format("Task is running on a thread id {0}. Is thread pool thread: {1}",
                Thread.CurrentThread.ManagedThreadId, Thread.CurrentThread.IsThreadPoolThread);
    }
}

public interface IAwaiter<T> : INotifyCompletion
{
    bool IsCompleted { get; }

    T GetResult();
}

class Program
{
    static void Main(string[] args)
    {
        var concurrentDictionary = new ConcurrentDictionary<int, string>();
        var dictionary = new Dictionary<int, string>();

        var sw = new Stopwatch();

        sw.Start();
        for (int i = 0; i < 1000000; i++)
        {
            lock (dictionary)
            {
                dictionary[i] = Item;
            }
        }
        sw.Stop();
        Console.WriteLine("Writing to dictionary with a lock: {0}", sw.Elapsed);

        sw.Restart();
        for (int i = 0; i < 1000000; i++)
        {
            concurrentDictionary[i] = Item;
        }
        sw.Stop();
        Console.WriteLine("Writing to a concurrent dictionary: {0}", sw.Elapsed);

        sw.Restart();
        for (int i = 0; i < 1000000; i++)
        {
            lock (dictionary)
            {
                CurrentItem = dictionary[i];
            }
        }
        sw.Stop();
        Console.WriteLine("Reading from dictionary with a lock: {0}", sw.Elapsed);

        sw.Restart();
        for (int i = 0; i < 1000000; i++)
        {
            CurrentItem = concurrentDictionary[i];
        }
        sw.Stop();
        Console.WriteLine("Reading from a concurrent dictionary: {0}", sw.Elapsed);

        Console.ReadKey();
    }

    const string Item = "Dictionary item";
    public static string CurrentItem;
}

class Program
{
    static void Main(string[] args)
    {
        Task t = RunProgram();
        t.Wait();
        Console.ReadKey();
    }

    static async Task RunProgram()
    {
        var taskQueue = new ConcurrentQueue<CustomTask>();
        var cts = new CancellationTokenSource();

        var taskSource = Task.Run(() => TaskProducer(taskQueue));

        Task[] processors = new Task[4];
        for (int i = 1; i <= 4; i++)
        {
            string processorId = i.ToString();
            processors[i-1] = Task.Run(
                () => TaskProcessor(taskQueue, "Processor " + processorId, cts.Token));
        }

        await taskSource;
        cts.CancelAfter(TimeSpan.FromSeconds(2));

        await Task.WhenAll(processors);
    }

    static async Task TaskProducer(ConcurrentQueue<CustomTask> queue)
    {
        for (int i = 1; i <= 20; i++)
        {
            await Task.Delay(50);
            var workItem = new CustomTask {Id = i};
            queue.Enqueue(workItem);
            Console.WriteLine("Task {0} has been posted", workItem.Id);
        }
    }

    static async Task TaskProcessor(
        ConcurrentQueue<CustomTask> queue, string name, CancellationToken token)
    {
        CustomTask workItem;
        bool dequeueSuccesful = false;

        await GetRandomDelay();
        do
        {
            dequeueSuccesful = queue.TryDequeue(out workItem);
            if (dequeueSuccesful)
            {
                Console.WriteLine("Task {0} has been processed by {1}", workItem.Id, name);
            }

            await GetRandomDelay();
        }
        while (!token.IsCancellationRequested);
    }

    static Task GetRandomDelay()
    {
        int delay = new Random(DateTime.Now.Millisecond).Next(1, 500);
        return Task.Delay(delay);
    }

    class CustomTask
    {
        public int Id { get; set; }
    }
}

class Program
{
    static void Main(string[] args)
    {
        Task t = RunProgram();
        t.Wait();

        Console.ReadKey();
    }

    static async Task RunProgram()
    {
        var taskStack = new ConcurrentStack<CustomTask>();
        var cts = new CancellationTokenSource();

        var taskSource = Task.Run(() => TaskProducer(taskStack));

        Task[] processors = new Task[4];
        for (int i = 1; i <= 4; i++)
        {
            string processorId = i.ToString();
            processors[i - 1] = Task.Run(
                () => TaskProcessor(taskStack, "Processor " + processorId, cts.Token));
        }

        await taskSource;
        cts.CancelAfter(TimeSpan.FromSeconds(2));

        await Task.WhenAll(processors);
    }

    static async Task TaskProducer(ConcurrentStack<CustomTask> stack)
    {
        for (int i = 1; i <= 20; i++)
        {
            await Task.Delay(50);
            var workItem = new CustomTask { Id = i };
            stack.Push(workItem);
            Console.WriteLine("Task {0} has been posted", workItem.Id);
        }
    }

    static async Task TaskProcessor(
        ConcurrentStack<CustomTask> stack, string name, CancellationToken token)
    {
        await GetRandomDelay();
        do
        {
            CustomTask workItem;
            bool popSuccesful = stack.TryPop(out workItem);
            if (popSuccesful)
            {
                Console.WriteLine("Task {0} has been processed by {1}", workItem.Id, name);
            }

            await GetRandomDelay();
        }
        while (!token.IsCancellationRequested);
    }

    static Task GetRandomDelay()
    {
        int delay = new Random(DateTime.Now.Millisecond).Next(1, 500);
        return Task.Delay(delay);
    }

    class CustomTask
    {
        public int Id { get; set; }
    }
}

    class Program
    {
        static void Main(string[] args)
        {
            CreateLinks();
            Task t = RunProgram();
            t.Wait();
        }

        static Dictionary<string, string[]> _contentEmulation = new Dictionary<string, string[]>();

        static async Task RunProgram()
        {
            var bag = new ConcurrentBag<CrawlingTask>();

            string[] urls = new[] {"http://microsoft.com/", "http://google.com/", "http://facebook.com/", "http://twitter.com/"};
        
            var crawlers = new Task[4];
            for (int i = 1; i <= 4; i++)
            {
                string crawlerName = "Crawler " + i.ToString();
                bag.Add(new CrawlingTask { UrlToCrawl = urls[i-1], ProducerName = "root"});
                crawlers[i - 1] = Task.Run(() => Crawl(bag, crawlerName));
            }

            await Task.WhenAll(crawlers);

            Console.ReadKey();
        }

        static async Task Crawl(ConcurrentBag<CrawlingTask> bag, string crawlerName)
        {
            CrawlingTask task;
            while (bag.TryTake(out task))
            {
                IEnumerable<string> urls = await GetLinksFromContent(task);
                if (urls != null)
                {
                    foreach (var url in urls)
                    {
                        var t = new CrawlingTask
                        {
                            UrlToCrawl = url,
                            ProducerName = crawlerName
                        };

                        bag.Add(t);
                    }
                }
                Console.WriteLine("Indexing url {0} posted by {1} is completed by {2}!",
                    task.UrlToCrawl, task.ProducerName, crawlerName);
            }
        }

        static async Task<IEnumerable<string>> GetLinksFromContent(CrawlingTask task)
        {
            await GetRandomDelay();

            if (_contentEmulation.ContainsKey(task.UrlToCrawl)) return _contentEmulation[task.UrlToCrawl];

            return null;
        }

        static void CreateLinks()
        {
            _contentEmulation["http://microsoft.com/"] = new [] { "http://microsoft.com/a.html", "http://microsoft.com/b.html" };
            _contentEmulation["http://microsoft.com/a.html"] = new[] { "http://microsoft.com/c.html", "http://microsoft.com/d.html" };
            _contentEmulation["http://microsoft.com/b.html"] = new[] { "http://microsoft.com/e.html" };

            _contentEmulation["http://google.com/"] = new[] { "http://google.com/a.html", "http://google.com/b.html" };
            _contentEmulation["http://google.com/a.html"] = new[] { "http://google.com/c.html", "http://google.com/d.html" };
            _contentEmulation["http://google.com/b.html"] = new[] { "http://google.com/e.html", "http://google.com/f.html" };
            _contentEmulation["http://google.com/c.html"] = new[] { "http://google.com/h.html", "http://google.com/i.html" };

            _contentEmulation["http://facebook.com/"] = new [] { "http://facebook.com/a.html", "http://facebook.com/b.html" };
            _contentEmulation["http://facebook.com/a.html"] = new[] { "http://facebook.com/c.html", "http://facebook.com/d.html" };
            _contentEmulation["http://facebook.com/b.html"] = new[] { "http://facebook.com/e.html" };

            _contentEmulation["http://twitter.com/"] = new[] { "http://twitter.com/a.html", "http://twitter.com/b.html" };
            _contentEmulation["http://twitter.com/a.html"] = new[] { "http://twitter.com/c.html", "http://twitter.com/d.html" };
            _contentEmulation["http://twitter.com/b.html"] = new[] { "http://twitter.com/e.html" };
            _contentEmulation["http://twitter.com/c.html"] = new[] { "http://twitter.com/f.html", "http://twitter.com/g.html" };
            _contentEmulation["http://twitter.com/d.html"] = new[] { "http://twitter.com/h.html" };
            _contentEmulation["http://twitter.com/e.html"] = new[] { "http://twitter.com/i.html" };
        }

        static Task GetRandomDelay()
        {
            int delay = new Random(DateTime.Now.Millisecond).Next(150, 200);
            return Task.Delay(delay);
        }

        class CrawlingTask
        {
            public string UrlToCrawl { get; set; }

            public string ProducerName { get; set; }
        }
    }

class Program
{
    static void Main(string[] args)
    {
        Console.WriteLine("Using a Queue inside of BlockingCollection");
        Console.WriteLine();
        Task t = RunProgram();
        t.Wait();

        Console.WriteLine();
        Console.WriteLine("Using a Stack inside of BlockingCollection");
        Console.WriteLine();
        t = RunProgram(new ConcurrentStack<CustomTask>());
        t.Wait();
    }

    static async Task RunProgram(IProducerConsumerCollection<CustomTask> collection = null)
    {
        var taskCollection = new BlockingCollection<CustomTask>();
        if(collection != null)
            taskCollection= new BlockingCollection<CustomTask>(collection);

        var taskSource = Task.Run(() => TaskProducer(taskCollection));

        Task[] processors = new Task[4];
        for (int i = 1; i <= 4; i++)
        {
            string processorId = "Processor " + i;
            processors[i - 1] = Task.Run(
                () => TaskProcessor(taskCollection, processorId));
        }

        await taskSource;

        await Task.WhenAll(processors);
    }

    static async Task TaskProducer(BlockingCollection<CustomTask> collection)
    {
        for (int i = 1; i <= 20; i++)
        {
            await Task.Delay(20);
            var workItem = new CustomTask { Id = i };
            collection.Add(workItem);
            Console.WriteLine("Task {0} has been posted", workItem.Id);
        }
        collection.CompleteAdding();
    }

    static async Task TaskProcessor(
        BlockingCollection<CustomTask> collection, string name)
    {
        await GetRandomDelay();
        foreach (CustomTask item in collection.GetConsumingEnumerable())
        {
            Console.WriteLine("Task {0} has been processed by {1}", item.Id, name);
            await GetRandomDelay();
        }
    }

    static Task GetRandomDelay()
    {
        int delay = new Random(DateTime.Now.Millisecond).Next(1, 500);
        return Task.Delay(delay);
    }

    class CustomTask
    {
        public int Id { get; set; }
    }

}

class Program
{
    static void Main(string[] args)
    {
        Parallel.Invoke(
            () => EmulateProcessing("Task1"),
            () => EmulateProcessing("Task2"),
            () => EmulateProcessing("Task3")
        );

        var cts = new CancellationTokenSource();

        var result = Parallel.ForEach(
            Enumerable.Range(1, 30),
            new ParallelOptions
            {
                CancellationToken = cts.Token,
                MaxDegreeOfParallelism = Environment.ProcessorCount,
                TaskScheduler = TaskScheduler.Default
            },
            (i, state) =>
            {
                Console.WriteLine(i);
                if (i == 20)
                {
                    state.Break();
                    Console.WriteLine("Loop is stopped: {0}", state.IsStopped);
                }
            });

        Console.WriteLine("---");
        Console.WriteLine("IsCompleted: {0}", result.IsCompleted);
        Console.WriteLine("Lowest break iteration: {0}", result.LowestBreakIteration);

        Console.ReadKey();
    }

    static string EmulateProcessing(string taskName)
    {
        Thread.Sleep(TimeSpan.FromMilliseconds(
            new Random(DateTime.Now.Millisecond).Next(250, 350)));
        Console.WriteLine("{0} task was processed on a thread id {1}",
                taskName, Thread.CurrentThread.ManagedThreadId);
        return taskName;
    }
}

class Program
{
    static void Main(string[] args)
    {
        var parallelQuery = from t in GetTypes().AsParallel()
                                                select EmulateProcessing(t);

        var cts = new CancellationTokenSource();
        cts.CancelAfter(TimeSpan.FromSeconds(3));

        try
        {
            parallelQuery
                .WithDegreeOfParallelism(Environment.ProcessorCount)
                .WithExecutionMode(ParallelExecutionMode.ForceParallelism)
                .WithMergeOptions(ParallelMergeOptions.Default)
                .WithCancellation(cts.Token)
                .ForAll(Console.WriteLine);
        }
        catch (OperationCanceledException)
        {
            Console.WriteLine("---");
            Console.WriteLine("Operation has been canceled!");
        }

        Console.WriteLine("---");
        Console.WriteLine("Unordered PLINQ query execution");
        var unorderedQuery = from i in ParallelEnumerable.Range(1, 30)
                                                 select i;

        foreach (var i in unorderedQuery)
        {
            Console.WriteLine(i);
        }

        Console.WriteLine("---");
        Console.WriteLine("Ordered PLINQ query execution");
        var orderedQuery = from i in ParallelEnumerable.Range(1, 30).AsOrdered()
                                                 select i;

        foreach (var i in orderedQuery)
        {
            Console.WriteLine(i);
        }

        Console.ReadKey();
    }

    static string EmulateProcessing(string typeName)
    {
        Thread.Sleep(TimeSpan.FromMilliseconds(
            new Random(DateTime.Now.Millisecond).Next(250,350)));
        Console.WriteLine("{0} type was processed on a thread id {1}",
                typeName, Thread.CurrentThread.ManagedThreadId);
        return typeName;
    }

    static IEnumerable<string> GetTypes()
    {
        return from assembly in AppDomain.CurrentDomain.GetAssemblies()
                     from type in assembly.GetExportedTypes()
                     where type.Name.StartsWith("Web")
                     orderby type.Name.Length
                     select type.Name;
    }
}

    internal class Program
    {
        static void Main(string[] args)
        {
            var t = ProcessAsynchronousIO();
            t.GetAwaiter().GetResult();

            Console.ReadKey();
        }

        const int BUFFER_SIZE = 4096;

        async static Task ProcessAsynchronousIO()
        {
            using (var stream = new FileStream("test1.txt", FileMode.Create, FileAccess.ReadWrite, FileShare.None, BUFFER_SIZE))
            {
                Console.WriteLine("1. Uses I/O Threads: {0}", stream.IsAsync);

                byte[] buffer = Encoding.UTF8.GetBytes(CreateFileContent());
                var writeTask = Task.Factory.FromAsync(stream.BeginWrite, stream.EndWrite, buffer, 0, buffer.Length, null);

                await writeTask;
            }

            using (var stream = new FileStream("test2.txt", FileMode.Create, FileAccess.ReadWrite, FileShare.None, BUFFER_SIZE, FileOptions.Asynchronous))
            {
                Console.WriteLine("2. Uses I/O Threads: {0}", stream.IsAsync);

                byte[] buffer = Encoding.UTF8.GetBytes(CreateFileContent());
                var writeTask = Task.Factory.FromAsync(stream.BeginWrite, stream.EndWrite, buffer, 0, buffer.Length, null);

                await writeTask;
            }

            using (var stream = File.Create("test3.txt", BUFFER_SIZE, FileOptions.Asynchronous))
            using (var sw = new StreamWriter(stream))
            {
                Console.WriteLine("3. Uses I/O Threads: {0}", stream.IsAsync);
                await sw.WriteAsync(CreateFileContent());
            }

            using (var sw = new StreamWriter("test4.txt", true))
            {
                Console.WriteLine("4. Uses I/O Threads: {0}", ((FileStream)sw.BaseStream).IsAsync);
                await sw.WriteAsync(CreateFileContent());
            }

            Console.WriteLine("Starting parsing files in parallel");

            Task<long>[] readTasks = new Task<long>[4];
            for (int i = 0; i < 4; i++)
            {
                readTasks[i] = SumFileContent(string.Format("test{0}.txt", i + 1));
            }

            long[] sums = await Task.WhenAll(readTasks);

            Console.WriteLine("Sum in all files: {0}", sums.Sum());

            Console.WriteLine("Deleting files...");

            Task[] deleteTasks = new Task[4];
            for (int i = 0; i < 4; i++)
            {
                string fileName = string.Format("test{0}.txt", i + 1);
                deleteTasks[i] = SimulateAsynchronousDelete(fileName);
            }

            await Task.WhenAll(deleteTasks);

            Console.WriteLine("Deleting complete.");
        }

        static string CreateFileContent()
        {
            var sb = new StringBuilder();
            for (int i = 0; i < 100000; i++)
            {
                sb.AppendFormat("{0}", new Random(i).Next(0, 99999));
                sb.AppendLine();
            }
            return sb.ToString();
        }

        async static Task<long> SumFileContent(string fileName)
        {
            using (var stream = new FileStream(fileName, FileMode.Open, FileAccess.Read, FileShare.None, BUFFER_SIZE, FileOptions.Asynchronous))
            using (var sr = new StreamReader(stream))
            {
                long sum = 0;
                while (sr.Peek() > -1)
                {
                    string line = await sr.ReadLineAsync();
                    sum += long.Parse(line);
                }

                return sum;
            }
        }

        static Task SimulateAsynchronousDelete(string fileName)
        {
            return Task.Run(() => File.Delete(fileName));
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            var server = new AsyncHttpServer(portNumber: 1234);
            var t = Task.Run(() => server.Start());
            Console.WriteLine("Listening on port 1234. Open http://localhost:1234 in your browser.");
            Console.WriteLine("Trying to connect:");
            Console.WriteLine();

            GetResponseAsync("http://localhost:1234").GetAwaiter().GetResult();

            Console.WriteLine();
            Console.WriteLine("Press Enter to stop the server.");
            Console.ReadLine();

            server.Stop().GetAwaiter().GetResult();

            Console.ReadKey();
        }

        static async Task GetResponseAsync(string url)
        {
            using (var client = new HttpClient())
            {
                HttpResponseMessage responseMessage = await client.GetAsync(url);
                string responseHeaders = responseMessage.Headers.ToString();
                string response = await responseMessage.Content.ReadAsStringAsync();

                Console.WriteLine("Response headers:");
                Console.WriteLine(responseHeaders);
                Console.WriteLine("Response body:");
                Console.WriteLine(response);
            }
        }

        class AsyncHttpServer
        {
            readonly HttpListener _listener;
            const string RESPONSE_TEMPLATE = "<html><head><title>Test</title></head><body><h2>Test page</h2><h4>Today is: {0}</h4></body></html>";

            public AsyncHttpServer(int portNumber)
            {
                _listener = new HttpListener();
                _listener.Prefixes.Add(string.Format("http://+:{0}/", portNumber));
            }

            public async Task Start()
            {
                _listener.Start();

                while (true)
                {
                    var ctx = await _listener.GetContextAsync();
                    Console.WriteLine("Client connected...");
                    var response = string.Format(RESPONSE_TEMPLATE, DateTime.Now);

                    using (var sw = new StreamWriter(ctx.Response.OutputStream))
                    {
                        await sw.WriteAsync(response);
                        await sw.FlushAsync();
                    }
                }
            }

            public async Task Stop()
            {
                _listener.Abort();
            }
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            const string dataBaseName = "CustomDatabase";
            var t = ProcessAsynchronousIO(dataBaseName);
            t.GetAwaiter().GetResult();
            Console.WriteLine("Press Enter to exit");
            Console.ReadLine();
        }

        async static Task ProcessAsynchronousIO(string dbName)
        {
            try
            {
                const string connectionString = @"Data Source=(LocalDB)\v11.0;Initial Catalog=master;Integrated Security=True";
                string outputFolder = Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location);
                string dbFileName = Path.Combine(outputFolder, string.Format(@".\{0}.mdf", dbName));
                string dbLogFileName = Path.Combine(outputFolder, string.Format(@".\{0}_log.ldf", dbName));
                string dbConnectionString = string.Format(@"Data Source=(LocalDB)\v11.0;AttachDBFileName={1};Initial Catalog={0};Integrated Security=True;", dbName, dbFileName);

                using (var connection = new SqlConnection(connectionString))
                {
                    await connection.OpenAsync();

                    if (File.Exists(dbFileName))
                    {
                        Console.WriteLine("Detaching the database...");

                        var detachCommand = new SqlCommand("sp_detach_db", connection);
                        detachCommand.CommandType = CommandType.StoredProcedure;
                        detachCommand.Parameters.AddWithValue("@dbname", dbName);

                        await detachCommand.ExecuteNonQueryAsync();

                        Console.WriteLine("The database was detached succesfully.");
                        Console.WriteLine("Deleteing the database...");

                        if(File.Exists(dbLogFileName)) File.Delete(dbLogFileName);
                        File.Delete(dbFileName);

                        Console.WriteLine("The database was deleted succesfully.");
                    }

                    Console.WriteLine("Creating the database...");
                    string createCommand = String.Format("CREATE DATABASE {0} ON (NAME = N‘{0}‘, FILENAME = ‘{1}‘)", dbName, dbFileName);
                    var cmd = new SqlCommand(createCommand, connection);

                    await cmd.ExecuteNonQueryAsync();
                    Console.WriteLine("The database was created succesfully");
                }

                using (var connection = new SqlConnection(dbConnectionString))
                {
                    await connection.OpenAsync();

                    var cmd = new SqlCommand("SELECT newid()", connection);
                    var result = await cmd.ExecuteScalarAsync();

                    Console.WriteLine("New GUID from DataBase: {0}", result);

                    cmd = new SqlCommand(@"CREATE TABLE [dbo].[CustomTable]( [ID] [int] IDENTITY(1,1) NOT NULL, [Name] [nvarchar](50) NOT NULL,
 CONSTRAINT [PK_ID] PRIMARY KEY CLUSTERED ([ID] ASC) ON [PRIMARY]) ON [PRIMARY]", connection);
                    await cmd.ExecuteNonQueryAsync();

                    Console.WriteLine("Table was created succesfully.");

                    cmd = new SqlCommand(@"INSERT INTO [dbo].[CustomTable] (Name) VALUES (‘John‘);
INSERT INTO [dbo].[CustomTable] (Name) VALUES (‘Peter‘);
INSERT INTO [dbo].[CustomTable] (Name) VALUES (‘James‘);
INSERT INTO [dbo].[CustomTable] (Name) VALUES (‘Eugene‘);", connection);
                    await cmd.ExecuteNonQueryAsync();

                    Console.WriteLine("Inserted data succesfully");
                    Console.WriteLine("Reading data from table...");

                    cmd = new SqlCommand(@"SELECT * FROM [dbo].[CustomTable]", connection);
                    using (SqlDataReader reader = await cmd.ExecuteReaderAsync())
                    {
                        while (await reader.ReadAsync())
                        {
                            var id = reader.GetFieldValue<int>(0);
                            var name = reader.GetFieldValue<string>(1);

                            Console.WriteLine("Table row: Id {0}, Name {1}", id, name);
                        }
                    }
                }
            }
            catch(Exception ex)
            {
                Console.WriteLine("Error: {0}", ex.Message);
            }
        }
    }