Python线程死锁

Question

我有两个线程(生产者和消费者)，我与 Queue 共享数据。问题是，当我强行中止生产者时，消费者有时会锁定。

我在文档中读到取消带有队列的线程可能会破坏队列并导致死锁。我没有明确获取任何锁，但阅读 Queue.py 的源代码说 put 和 get 正在这样做。

拜托，有谁知道当我中止线程时，它可能在 get/put 的中间，即使用锁然后不释放它？我该怎么办？有时我需要提前终止生产者。使用进程而不是线程会有什么不同吗？

Answer 1

也许这会有所帮助:

import threading

class MyQueue:
    def __init__(self):
        self.tasks = []
        self.tlock = threading.Semaphore(0)
        self.dlock = threading.Lock()
        self.aborted = False

    def put(self, arg):
        try:
            self.dlock.acquire()
            self.tasks.append(arg)
        finally:
            self.dlock.release()
            self.tlock.release()

    def get(self):
        if self.aborted:
            return None
        self.tlock.acquire()
        if self.aborted:
            self.tlock.release()
            return None
        try:
            self.dlock.acquire()
            if self.tasks:
                return self.tasks.pop()
            else: # executed abort
                return None
        finally:
            self.dlock.release()

    def abort(self):
        self.aborted = True
        self.tlock.release()

# TESTING

mq = MyQueue()
import sys

def tlog(line):
    sys.stdout.write("[ %s ] %s\n" % (threading.currentThread().name, line))
    sys.stdout.flush()

def reader():
    arg = 1
    while arg is not None:
        tlog("start reading")
        arg = mq.get()
        tlog("read: %s" % arg)
    tlog("END")

import time, random
def writer():
    try:
        pos = 1
        while not mq.aborted:
            x = random.random() * 5
            tlog("writer sleep (%s)" % x)
            pending = x
            while pending > 0:
                tosleep = min(0.5, pending)
                if mq.aborted:
                    return
                time.sleep(tosleep)
                pending -= tosleep

            tlog("write: %s" % x)
            mq.put("POS %s  val=%s" % (pos, x))
            pos += 1
    finally:
        tlog("writer END")

def testStart():
    try:
        for i in xrange(9):
            th = threading.Thread(None, reader, "reader %s" % i, (), {}, None)
            th.start()
        for i in xrange(3):
            th = threading.Thread(None, writer, "writer %s" % i, (), {}, None)
            th.start()
        time.sleep(30) # seconds for testing
    finally:
        print "main thread: abort()"
        mq.abort()

if __name__ == "__main__":
    testStart()