为什么当代码执行时,结果每次都不同?
我试图遵循代码是如何执行的,我感到困惑,我觉得这是没有意义的。
每次结果都是随机出现的
#!/usr/bin/python
import Queue
import threading
import time
exitFlag = 0
class myThread (threading.Thread):
def __init__(self, threadID, name, q):
threading.Thread.__init__(self)
self.threadID = threadID
self.name = name
self.q = q
def run(self):
print "Starting " + self.name
process_data(self.name, self.q)
print "Exiting " + self.name
def process_data(threadName, q):
while not exitFlag:
queueLock.acquire()
if not workQueue.empty():
data = q.get()
queueLock.release()
print "%s processing %s" % (threadName, data)
else:
queueLock.release()
time.sleep(1)
threadList = ["Thread-1", "Thread-2", "Thread-3"]
nameList = ["One", "Two", "Three", "Four", "Five"]
queueLock = threading.Lock()
workQueue = Queue.Queue(10)
threads = []
threadID = 1
# Create new threads
for tName in threadList:
thread = myThread(threadID, tName, workQueue)
thread.start()
threads.append(thread)
threadID += 1
# Fill the queue
queueLock.acquire()
for word in nameList:
workQueue.put(word)
queueLock.release()
# Wait for queue to empty
while not workQueue.empty():
pass
# Notify threads it's time to exit
exitFlag = 1
# Wait for all threads to complete
for t in threads:
t.join()
print "Exiting Main Thread"
代码源multithreading.htm
更新
抱歉,我是说结果的顺序
就像这样:
Starting Thread-1
Starting Thread-2
Starting Thread-3
Thread-3 processing One
Thread-2 processing Two
Thread-1 processing Three
Thread-3 processing Four
Thread-2 processing Five
Exiting Thread-1
Exiting Thread-3
Exiting Thread-2
Exiting Main Thread
[Finished in 3.0s]
如果再试一次,结果
Starting Thread-1
Starting Thread-2
Starting Thread-3
Thread-3 processing One
Thread-2 processing Two
Thread-1 processing Three
Thread-3 processing Four
Thread-3 processing Five
Exiting Thread-1
Exiting Thread-2
Exiting Thread-3
Exiting Main Thread
[Finished in 3.0s]
发布于 2013-10-07 08:00:10
我想,你所说的“结果”是指执行命令。多线程背后的一个想法是,除非您想要明确地指定执行顺序,否则您不必关心执行顺序。你完全依赖底层操作系统,系统负载,.等。
https://stackoverflow.com/questions/19219570
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