如何将数据发送到正在运行的 python 线程?

2024-01-07

我有一个类在我的应用程序中的单独线程中运行。我可以同时运行多个线程,并且这些线程是守护进程。经过一段时间后,some这些线程需要接收并处理消息。我该怎么做呢?

我的代码示例如下所示:

import threading
import time 

class MyThread(threading.Thread):
    def __init__(self, args=(), kwargs=None):
        threading.Thread.__init__(self, args=(), kwargs=None)
        self.daemon = True
        self.receive_messages = args[0]

    def run(self):
        print threading.currentThread().getName(), self.receive_messages

    def do_thing_with_message(self, message):
        if self.receive_messages:
            print threading.currentThread().getName(), "Received %s".format(message)

if __name__ == '__main__':
    threads = []
    for t in range(10):
        threads.append( MyThread(args=(t % 2 == 0,)))
        threads[t].start()
        time.sleep(0.1)

    for t in threads:
        t.do_thing_with_message("Print this!")

这输出:

Thread-1 True
Thread-2 False
Thread-3 True
Thread-4 False
Thread-5 True
Thread-6 False
Thread-7 True
Thread-8 False
Thread-9 True
Thread-10 False
MainThread Received %s
MainThread Received %s
MainThread Received %s
MainThread Received %s
MainThread Received %s

然而,我预计最后五行与MainThread,而不是%s,我希望它对我来说Print this!,像这样:

Thread-1 True
Thread-2 False
Thread-3 True
Thread-4 False
Thread-5 True
Thread-6 False
Thread-7 True
Thread-8 False
Thread-9 True
Thread-10 False
Thread-1 Received Print this!
Thread-3 Received Print this!
Thread-5 Received Print this!
Thread-7 Received Print this!
Thread-9 Received Print this!

如何正确地将这样的消息发送到正在运行的线程?

附录:

如果我在之后有这个块Print this!阻止,并利用@dano的代码解决上述问题,它似乎没有响应这些新消息。

for t in threads:
    t.queue.put("Print this again!")
    time.sleep(0.1)

在这种情况下,我希望输出的结尾看起来像这样

Thread-1 Received Print this!
Thread-3 Received Print this!
Thread-5 Received Print this!
Thread-7 Received Print this!
Thread-9 Received Print this!
Thread-1 Received Print this again!
Thread-3 Received Print this again!
Thread-5 Received Print this again!
Thread-7 Received Print this again!
Thread-9 Received Print this again!

您可以使用Queue.Queue https://docs.python.org/2/library/queue.html#queue-objects (or queue.Queue在 Python 3) 中:

import threading
import time 
from Queue import Queue

print_lock = threading.Lock()

class MyThread(threading.Thread):
    def __init__(self, queue, args=(), kwargs=None):
        threading.Thread.__init__(self, args=(), kwargs=None)
        self.queue = queue
        self.daemon = True
        self.receive_messages = args[0]

    def run(self):
        print threading.currentThread().getName(), self.receive_messages
        val = self.queue.get()
        self.do_thing_with_message(val)

    def do_thing_with_message(self, message):
        if self.receive_messages:
            with print_lock:
                print threading.currentThread().getName(), "Received {}".format(message)

if __name__ == '__main__':
    threads = []
    for t in range(10):
        q = Queue()
        threads.append(MyThread(q, args=(t % 2 == 0,)))
        threads[t].start()
        time.sleep(0.1)

    for t in threads:
        t.queue.put("Print this!")

    for t in threads:
        t.join()

我们通过一个Queue实例到每个线程,并将我们的消息发送到Thread using queue.put。我们等待消息到达run方法,这是Thread实际上在单独的执行线程中运行的对象。收到消息后,我们会致电do_thing_with_message,它将在同一个后台线程中运行。

我还添加了一个threading.Lock https://docs.python.org/2/library/threading.html#threading.Lock到代码中,这样打印到标准输出就不会混淆。

Edit:

如果您希望能够向线程传递多条消息,只需使用循环即可:

def run(self):
    print threading.currentThread().getName(), self.receive_messages
    while True:
        val = self.queue.get()
        if val is None:   # If you send `None`, the thread will exit.
            return
        self.do_thing_with_message(val)
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