标签：提交 font tsig detail div 线程 spl alt create
在多线程中，有时候需要等待所有线程执行完成后才让继续往下执行，如查询结果汇总等。下面列举两种等待方式：
方式一： 利用 CountDownLatch 类完成。
示例：
// 按任务总量创建计数器
final CountDownLatch countDownLatch = new CountDownLatch(sourceList.size() - 1); for (int i = 1; i < sourceList.size(); i++) { final int index = i; // 线程池提交任务 threadPoolExecutor.submit(new Runnable() { @Override public void run() { try {// 单个计算 work(); } finally {
// 计数器-1 countDownLatch.countDown(); } } }); } try {
// 等待计数器归0 countDownLatch.await(); } catch (Exception e) { }
JDK源码示例参考：
class Driver { // ... * void main() throws InterruptedException { * CountDownLatch startSignal = new CountDownLatch(1); * CountDownLatch doneSignal = new CountDownLatch(N); * * for (int i = 0; i < N; ++i) // create and start threads * new Thread(new Worker(startSignal, doneSignal)).start(); * * doSomethingElse(); // don‘t let run yet * startSignal.countDown(); // let all threads proceed * doSomethingElse(); * doneSignal.await(); // wait for all to finish * } * } * * class Worker implements Runnable { * private final CountDownLatch startSignal; * private final CountDownLatch doneSignal; * Worker(CountDownLatch startSignal, CountDownLatch doneSignal) { * this.startSignal = startSignal; * this.doneSignal = doneSignal; * } * public void run() { * try { * startSignal.await(); * doWork(); * doneSignal.countDown(); * } catch (InterruptedException ex) {} // return; * } * * void doWork() { ... } * }} * class Driver2 { // ... * void main() throws InterruptedException { * CountDownLatch doneSignal = new CountDownLatch(N); * Executor e = ... * * for (int i = 0; i < N; ++i) // create and start threads * e.execute(new WorkerRunnable(doneSignal, i)); * * doneSignal.await(); // wait for all to finish * } * } * * class WorkerRunnable implements Runnable { * private final CountDownLatch doneSignal; * private final int i; * WorkerRunnable(CountDownLatch doneSignal, int i) { * this.doneSignal = doneSignal; * this.i = i; * } * public void run() { * try { * doWork(i); * doneSignal.countDown(); * } catch (InterruptedException ex) {} // return; * } * * void doWork() { ... } * }}
方式二： 利用任务自身的阻塞能力阻塞主线程执行。
示例：
private ThreadPoolExecutor threadPoolExecutor = null; private void init() {// 线程池初始化 BlockingQueue<Runnable> blockingQueue = new LinkedBlockingDeque<Runnable>(30); threadPoolExecutor = new ThreadPoolExecutor(1,1, 0, TimeUnit.SECONDS, blockingQueue, new ThreadPoolExecutor.CallerRunsPolicy()); } // 批量任务生成 List<FutureTask<Result<Long>>> taskList = new LinkedList<>(); for (String sql : sqlList) { FutureTask<Result<Long>> task = new FutureTask(new Callable<Result<Long>>() { @Override public Result<Long> call() throws Exception { return querySql(sql); } }); taskList.add(task); } // 批量执行 for (FutureTask<Result<Long>> task : taskList) { threadPoolExecutor.execute(task); } // 结果汇总 Long cnt = 0L; for (FutureTask<Result<Long>> task : taskList) { try { // 任务结果获取，会阻塞主线程等待执行结束 Result<Long> value = task.get(); if (value.isSuccess()) { cnt = cnt + value.getValue(); } } catch (Throwable e) { } }
与 submit 类似的，参考：
https://blog.csdn.net/m0_37822338/article/details/100010495
标签：提交 font tsig detail div 线程 spl alt create
原文地址：https://www.cnblogs.com/guihong/p/13076997.html
