标签:import div img http end pre class 图片 []
单线程程序:
import time def Sorry(): print "I‘m sorry!" time.sleep(1) if __name__==‘__main__‘: for i in range(5): Sorry()
添加线程
import threading
def thread_job():
print ‘this is an added Thread,number is %s‘ % threading.current_thread()
if __name__ == ‘__main__‘:
added_thread = threading.Thread(target=thread_job)
added_thread.start()
join 等待线程结束之后再往下执行
import time,threading def thread_job(): print ‘T1 start\n‘ for i in range(10): time.sleep(0.1) print ‘T1 finish\n‘ def mian(): added_thread = threading.Thread(target=thread_job,name=‘T1‘) added_thread.start() print ‘all done\n‘ if __name__ == ‘__main__‘: mian()
import time,threading def thread_job(): print ‘T1 start\n‘ for i in range(10): time.sleep(0.1) print ‘T1 finish\n‘ def mian(): added_thread = threading.Thread(target=thread_job,name=‘T1‘) added_thread.start() added_thread.join() print ‘all done\n‘ if __name__ == ‘__main__‘: mian()
Queue功能,因为线程中不能使用return
import time,threading from queue import Queue def job(l,q): for i in range(len(l)): l[i] = l[i]**2 q.put(l) def multithreading(): q = Queue() threads = [] data = [[1,2,3],[3,4,5],[4,4,4],[5,5,5]] for i in range(4): t = threading.Thread(target=job,args=(data[i],q)) t.start() threads.append(t) for thread in threads: thread.join() results = [] for _ in range(4): results.append(q.get()) print results if __name__ == ‘__main__‘: multithreading()
lock锁
import threading def job1(): global A for i in range(10): A += 1 print ‘job1 %d‘ % A def job2(): global A for i in range(10): A += 10 print ‘job2 %d‘ % A if __name__ == ‘__main__‘: A = 0 t1 = threading.Thread(target=job1) t2 = threading.Thread(target=job2) t1.start() t2.start() t1.join() t2.join()
import threading def job1(): global A,lock lock.acquire() for i in range(10): A += 1 print ‘job1 %d‘ % A lock.release() def job2(): global A,lock lock.acquire() for i in range(10): A += 10 print ‘job2 %d‘ % A lock.release() if __name__ == ‘__main__‘: lock = threading.Lock() A = 0 t1 = threading.Thread(target=job1) t2 = threading.Thread(target=job2) t1.start() t2.start() t1.join() t2.join()
ps:多线程不一定有效率,有GIL锁的存在,python只能同一时间让一个线程运算同一个运算
import threading from queue import Queue import copy import time def job(l, q): res = sum(l) q.put(res) def multithreading(l): q = Queue() threads = [] for i in range(4): t = threading.Thread(target=job, args=(copy.copy(l), q), name=‘T%i‘ % i) t.start() threads.append(t) [t.join() for t in threads] total = 0 for _ in range(4): total += q.get() print(total) def normal(l): total = sum(l) print(total) if __name__ == ‘__main__‘: l = list(range(1000000)) s_t = time.time() normal(l*4) print(‘normal: ‘,time.time()-s_t) s_t = time.time() multithreading(l) print(‘multithreading: ‘, time.time()-s_t)
标签:import div img http end pre class 图片 []
原文地址:https://www.cnblogs.com/mohu/p/8889665.html