threads.py 文件源码

def _thread_wrapper(self, *args):
        ''' Wrapper for the worker method defined in the module. Handles calling the actual worker, cleanly exiting upon
        interrupt, and passing exceptions back to the main process.'''
        thread_name = threading.current_thread().name
        self.debug('THREAD => %s started.' % thread_name)
        while not self.stopped.is_set():
            try:
                # use the get_nowait() method for retrieving a queued item to
                # prevent the thread from blocking when the queue is empty
                obj = self.q.get_nowait()
            except Empty:
                continue
            try:
                # launch the public module_thread method
                self.module_thread(obj, *args)
            except:
                # handle exceptions local to the thread
                self.print_exception('(thread=%s, object=%s)' % (thread_name, repr(obj)))
            finally:
                self.q.task_done()
        self.debug('THREAD => %s exited.' % thread_name)

    # sometimes a keyboardinterrupt causes a race condition between when the self.q.task_done() call above and the
    # self.q.empty() call below, causing all the threads to hang. introducing the time.sleep(.7) call below reduces
    # the likelihood of encountering the race condition.