python - 如何停止(并重启!)Tornado 服务器？

Question

我希望能够停止和重新启动 Tornado 服务器以进行测试和演示。但是好像没有释放端口。

以下代码基于answer showing how to properly stop Tornado .我刚刚在底部添加了尝试重启 Tornado 的代码。它因“错误:地址正在使用”异常而失败。我什至添加了对 ioloop.close() 的调用，但这没有帮助。

#! /usr/bin/env python

import threading
import tornado.ioloop
import tornado.web
import time


class MainHandler(tornado.web.RequestHandler):
    def get(self):
        self.write("Hello, world!\n")

def start_tornado(*args, **kwargs):
    application = tornado.web.Application([
        (r"/", MainHandler),
    ])
    application.listen(8888)
    print "Starting Torando"
    tornado.ioloop.IOLoop.instance().start()
    print "Tornado finished"

def stop_tornado():
    ioloop = tornado.ioloop.IOLoop.instance()
    ioloop.add_callback(ioloop.stop)
    ioloop.add_callback(ioloop.close) # I added this but it didn't help.
    print "Asked Tornado to exit"

def main():

    t = threading.Thread(target=start_tornado)
    t.start()

    time.sleep(1)

    stop_tornado()
    t.join()
    print "Tornado thread stopped."

    t = threading.Thread(target=start_tornado) # Attempt restart.
    t.start()

if __name__ == "__main__":
    main()

输出:

Starting Torando
Asked Tornado to exit
 Tornado finished
Tornado thread stopped.
Exception in thread Thread-2:
    Traceback (most recent call last):
          File "/home/mudd/musl/Python-2.7.11.install/lib/python2.7/threading.py", line 801, in __bootstrap_inner
    self.run()
  File "/home/mudd/musl/Python-2.7.11.install/lib/python2.7/threading.py", line 754, in run
    self.__target(*self.__args, **self.__kwargs)
  File "./test_tonado_restart.py", line 17, in start_tornado
    application.listen(8888)
  File "/home/mudd/musl/Python-2.7.11.install/lib/python2.7/site-packages/tornado/web.py", line 1825, in listen
    server.listen(port, address)
  File "/home/mudd/musl/Python-2.7.11.install/lib/python2.7/site-packages/tornado/tcpserver.py", line 126, in listen
    sockets = bind_sockets(port, address=address)
  File "/home/mudd/musl/Python-2.7.11.install/lib/python2.7/site-packages/tornado/netutil.py", line 196, in bind_sockets
    sock.bind(sockaddr)
  File "/home/mudd/musl/Python-2.7.11.install/lib/python2.7/socket.py", line 228, in meth
    return getattr(self._sock,name)(*args)
error: [Errno 98] Address in use

Answer 1

除非您确实需要，否则不要使用这样的线程 - 它们会使事情复杂化。对于测试，请使用 tornado.testing.AsyncTestCase 或 AsyncHTTPTestCase。

要释放端口，您需要停止HTTPServer，而不仅仅是IOLoop。事实上，您甚至可能根本不需要停止 IOLoop。 (但通常我会通过让进程退出并从头重新启动来重新启动一切)。

您的示例的非线程版本类似于:

#! /usr/bin/env python

import tornado.ioloop
import tornado.web
import time


class MainHandler(tornado.web.RequestHandler):
    def get(self):
        self.write("Hello, world!\n")

def start_app(*args, **kwargs):
    application = tornado.web.Application([
        (r"/", MainHandler),
    ])
    server = application.listen(8888)
    print "Starting app"
    return server

def stop_tornado():
    ioloop = tornado.ioloop.IOLoop.current()
    ioloop.add_callback(ioloop.stop)
    print "Asked Tornado to exit"

def main():
    server = start_app()
    tornado.ioloop.IOLoop.current().add_timeout(
        datetime.timedelta(seconds=1),
        stop_tornado)
    tornado.ioloop.IOLoop.current().start()
    print "Tornado finished"
    server.stop()

    # Starting over
    start_app()
    tornado.ioloop.IOLoop.current().start()