Question

我不知道如何解决这个问题：

Traceback（最近一次调用最后一次）：文件＆＃34; /usr/local/cabinet_dev/cabinet/lib/python3.4/site-packages/eventlet/hubs/hub.py" ;, 第458行，在fire_timers中 timer（）File＆＃34; /usr/local/cabinet_dev/cabinet/lib/python3.4/site-packages/eventlet/hubs/timer.py"，第58行，致电 cb（* args，** kw）File＆＃34; /usr/local/cabinet_dev/cabinet/lib/python3.4/site-packages/eventlet/greenthread.py"，第218行，主要 result = function（* args，** kwargs）文件＆＃34; ./ monitor.py＆＃34;，第148行，在caughtBridge中对于self.active.keys（）中的调用：RuntimeError：迭代期间字典改变了大小

在下面的代码中：

def caughtBridge(self):
    while True:
        event = self.bridgeQueue.get()
        uniqueid1 = str(event.headers.get('Uniqueid1'))
        uniqueid2 = str(event.headers.get('Uniqueid2'))
        for call in self.active.keys():
            if self.active[call]['uniqueid'] == uniqueid1:
                self.active[call]['uniqueid2'] = uniqueid2
            if self.active[call]['uniqueid'] == uniqueid1:
                for listener in self.listeners:
                    for number in listener.getNumbers():
                        if number == self.active[call]['exten']:
                            if not self.active[call]['answered']:
                                self.sendEvent({"status": "bridge", "id": self.active[call]['uniqueid'],
                                                "number": self.active[call]['exten']},
                                               listener.getRoom())
                                self.__callInfo(self.active[call], listener.getRoom())
                                self.active[call]['answered'] = True
        self.bridgeQueue.task_done()

Answer 1

使用self.active.keys()的副本，例如：

for call in list(self.active.keys()):

未检测到添加或删除 dict条目？
如果添加，其他线程将看不到添加的dict条目。
如果删除，当前线程将因 键错误 而失败，你必须抓住这些。

例如：

for call in list(self.active.keys()):
    <Lock that call to prevent removing>
    if call in self.active:
        ...
                      self.active[call]['answered'] = True
    else:
        # call removed do nothing
    <Unlocked that call to do whatever in other Thread>
self.bridgeQueue.task_done()

阅读Python»3.6.2文档：threading.html#lock-objects

基本实现配对方法self.lock(call)和self.unlock(call)，例如：

未经测试的代码：
要防止死锁，您必须保证会self.unlock(call)到达！

class xxx
    def __init__....
        self_lock = threading.Lock
        # Init all  self.active[call]['lock'] = False

def lock(self, call):
    # self._lock ist class threading.Lock
    # self._lock has to be the same for all Threads
    with self._lock:
        if call in self.active and not self.active[call]['lock']:
            self.active[call]['lock'] = True
            return True
        else:
            return False

def unlock(self, call):
    with self._lock:
        self.active[call]['lock'] = False

# Usage:
for call in list(self.active.keys()):
    if self.lock(call):
        ...
                      self.active[call]['answered'] = True

        self.unlock(call)
    else:
        # call removed do nothing
self.bridgeQueue.task_done()

字典在多线程应用程序的迭代期间改变了大小

1 个答案: