Python：'thread._local 对象没有属性'todo'

Question

我目前正在使用线程和所有这些来编写基于 python 的数据报服务器。

我遇到了以下问题：我正在使用多个分配线程将传入的包分配给不同的处理线程。在处理线程中，我使用 threading.local() 来跟踪线程局部变量。

我目前正在测试我的服务器在高负载期间的反应（大约 2 秒内 2000 个数据包），并且遇到了 local()-Object 的奇怪行为。

它似乎在一段时间内工作得很好，然后，在某些时候，它抛出了一个异常：

Exception in thread 192.168.1.102: # <-- This is the Processing Thread
Traceback (most recent call last):
  File "/opt/lib/python2.7/threading.py", line 552, in __bootstrap_inner
    self.run()
  File "/volume1/home/Max/Python/MyThread/pyProcThread.py", line 37, in run
    print self.loc.father
AttributeError: 'thread._local' object has no attribute 'father'

# The following three lines are debug
# This is the Allocation thread that has called the Processing thread
<Thread(192.168.1.102, started 1106023568)> 
# This confirms that the queue it tries to access exists
<Queue.Queue instance at 0x40662b48>
# This is the Processing thread, which has stopped executing on exception
<Thread(192.168.1.102, stopped 1106023568)> 

Exception in thread pyAlloc-0: # <-- This is the Allocation thread
Traceback (most recent call last):
  File "/opt/lib/python2.7/threading.py", line 552, in __bootstrap_inner
    self.run()
  File "/volume1/home/Max/Python/MyThread/pyAllocThread.py", line 60, in run
    foundThread.addTask(str(data))
  File "/volume1/home/Max/Python/MyThread/pyProcThread.py", line 58, in addTask
    print self.loc.todo
AttributeError: 'thread._local' object has no attribute 'todo'

处理线程的一部分

# Imports
import threading
import time
import Queue

class Thread(threading.Thread):
    def __init__(self,pThread):
        threading.Thread.__init__(self)
        self.loc = threading.local()
        self.loc.todo = Queue.Queue()
        self.loc.father = pThread
        print "Konstruktor ausgefuehrt"
        print self.loc.todo

    def run(self):
        self.loc.run = True;
        print self.loc.father
        while (self.loc.run):
        try:
            task = self.loc.todo.get(True, 1)
            print "processing..."
            if(task == self):
                self.loc.run=False
            else:
                print task
        except Queue.Empty:
            pass
        self.loc.father.threadTerminated(self)
        print self.name, "terminating..."

    def addTask(self, pTask):
        print self
        print self.loc.todo
        self.loc.todo.put(pTask)

以及分配线程：

import threading
import pyProcThread # My processing Thread
import Queue
import time
class Thread(threading.Thread):
    # Lock-Objects
    threadListLock = threading.Lock()
    waitListLock = threading.Lock()

    alive = True;

    taskQueue = Queue.Queue()
    # Lists
    # List of all running threads
    threads = []

    def threadExists(self,pIP):
        """Checks if there is already a thread with the given Name"""
        for x in self.threads:
            if x.name == pIP:
                return x
        return None

    def threadTerminated(self,pThread):
        """Called when a Processing Thread terminates"""
        with self.threadListLock:
            self.threads.remove(pThread)
            print "Thread removed"

    def threadRegistered(self,pThread):
        """Registers a new Thread"""
        self.threads.append(pThread)

    def killThread(self):
        self.alive = False

    def run(self):
        while(self.alive):
            # print "Verarbeite Nachricht ", self.Message
            # print "Von ", self.IP
            try:
                data, addtemp = self.taskQueue.get(True, 1)
                addr, _junk = addtemp
                with self.threadListLock:
                    foundThread=self.threadExists(str(addr))
                    # print "Thread " + self.name + " verarbeitet " + data
                    if (foundThread!=None):
                        #print "recycling thread"
                        foundThread.addTask(str(data))
                    else:
                        print "running new Thread"
                        t = pyProcThread.Thread(self)
                        t.name = str(addr)
                        t.addTask(str(data))
                        t.start()
                        self.threadRegistered(t)
                self.taskQueue.task_done()
            except Queue.Empty:
                pass
        print self.name, "terminating..."
        with self.threadListLock:
            for thread in self.threads:
                thread.addTask(thread)

完整的输出，包括所有调试打印：

running new Thread
Konstruktor ausgefuehrt
<Queue.Queue instance at 0x40662b48>
<Thread(192.168.1.102, initial)>
<Queue.Queue instance at 0x40662b48>
<Thread(192.168.1.102, started 1106023568)>
<Queue.Queue instance at 0x40662b48>
<Thread(192.168.1.102, started 1106023568)>
<Queue.Queue instance at 0x40662b48>
<Thread(192.168.1.102, started 1106023568)>
<Queue.Queue instance at 0x40662b48>
<Thread(192.168.1.102, started 1106023568)>
<Queue.Queue instance at 0x40662b48>
<Thread(192.168.1.102, started 1106023568)>
<Queue.Queue instance at 0x40662b48>
<Thread(192.168.1.102, started 1106023568)>
<Queue.Queue instance at 0x40662b48>
<Thread(192.168.1.102, started 1106023568)>
<Queue.Queue instance at 0x40662b48>
Exception in thread 192.168.1.102:
Traceback (most recent call last):
  File "/opt/lib/python2.7/threading.py", line 552, in __bootstrap_inner
    self.run()
  File "/volume1/home/Max/Python/MyThread/pyProcThread.py", line 37, in run
    print self.loc.father
AttributeError: 'thread._local' object has no attribute 'father'

<Thread(192.168.1.102, started 1106023568)>
<Queue.Queue instance at 0x40662b48>
<Thread(192.168.1.102, stopped 1106023568)>
Exception in thread pyAlloc-0:
Traceback (most recent call last):
  File "/opt/lib/python2.7/threading.py", line 552, in __bootstrap_inner
    self.run()
  File "/volume1/home/Max/Python/MyThread/pyAllocThread.py", line 60, in run
    foundThread.addTask(str(data))
  File "/volume1/home/Max/Python/MyThread/pyProcThread.py", line 58, in addTask
    print self.loc.todo
AttributeError: 'thread._local' object has no attribute 'todo'

Terminating main
192.168.1.102
DEINEMUDDA  sent to  192.168.1.102 : 8082
pyAlloc-1 terminating...
<Thread(192.168.1.102, stopped 1106023568)>
<Queue.Queue instance at 0x40662b48>

正如您在日志中看到的，一切似乎都正常运行了一段时间，尽管它从未到达处理线程的主函数中的print "processing。

我已经在网络和 StackOverflow 上搜索过类似的问题，但找不到任何问题。在此先感谢您的帮助，并原谅我的编码风格，我现在才编程 Python 几天，并且仍在学习它的一些功能。

编辑：当然，这个服务器还有比这个更多的东西。有一个主线程正在接收数据包并将它们发送到分配线程，还有一堆其他的东西在后台。此外，服务器还远未完成，但我希望在开始处理其他事情之前让接收工作正常。

Answer 1

threading.local 是表示线程本地数据的类。线程本地数据是其值是线程特定的数据，因此仅可用于 local 线程（创建local() 对象的线程）。换句话说，只有设置值的线程才能看到该值。

因为您在处理线程的__init__ 方法中设置了loc.parent 值，但在分配器线程内执行，所以处理线程的线程局部变量将仅在分配器线程中可用。所以它不会在处理线程的run() 中工作，因为它将由不同的线程（而不是分配器）执行。