Issue #2302: Fix a race condition in SocketServer.BaseServer.shutdown,
where the method could block indefinitely if called just before the
event loop started running. This also fixes the occasional freezes
witnessed in test_httpservers.
diff --git a/Lib/SocketServer.py b/Lib/SocketServer.py
index ff56d98..f0db511 100644
--- a/Lib/SocketServer.py
+++ b/Lib/SocketServer.py
@@ -198,7 +198,7 @@
self.server_address = server_address
self.RequestHandlerClass = RequestHandlerClass
self.__is_shut_down = threading.Event()
- self.__serving = False
+ self.__shutdown_request = False
def server_activate(self):
"""Called by constructor to activate the server.
@@ -215,17 +215,19 @@
self.timeout. If you need to do periodic tasks, do them in
another thread.
"""
- self.__serving = True
self.__is_shut_down.clear()
- while self.__serving:
- # XXX: Consider using another file descriptor or
- # connecting to the socket to wake this up instead of
- # polling. Polling reduces our responsiveness to a
- # shutdown request and wastes cpu at all other times.
- r, w, e = select.select([self], [], [], poll_interval)
- if r:
- self._handle_request_noblock()
- self.__is_shut_down.set()
+ try:
+ while not self.__shutdown_request:
+ # XXX: Consider using another file descriptor or
+ # connecting to the socket to wake this up instead of
+ # polling. Polling reduces our responsiveness to a
+ # shutdown request and wastes cpu at all other times.
+ r, w, e = select.select([self], [], [], poll_interval)
+ if self in r:
+ self._handle_request_noblock()
+ finally:
+ self.__shutdown_request = False
+ self.__is_shut_down.set()
def shutdown(self):
"""Stops the serve_forever loop.
@@ -234,7 +236,7 @@
serve_forever() is running in another thread, or it will
deadlock.
"""
- self.__serving = False
+ self.__shutdown_request = True
self.__is_shut_down.wait()
# The distinction between handling, getting, processing and
diff --git a/Lib/test/test_socketserver.py b/Lib/test/test_socketserver.py
index a938831..4f0dd3e 100644
--- a/Lib/test/test_socketserver.py
+++ b/Lib/test/test_socketserver.py
@@ -241,6 +241,31 @@
# SocketServer.DatagramRequestHandler,
# self.dgram_examine)
+ @reap_threads
+ def test_shutdown(self):
+ # Issue #2302: shutdown() should always succeed in making an
+ # other thread leave serve_forever().
+ class MyServer(SocketServer.TCPServer):
+ pass
+
+ class MyHandler(SocketServer.StreamRequestHandler):
+ pass
+
+ threads = []
+ for i in range(20):
+ s = MyServer((HOST, 0), MyHandler)
+ t = threading.Thread(
+ name='MyServer serving',
+ target=s.serve_forever,
+ kwargs={'poll_interval':0.01})
+ t.daemon = True # In case this function raises.
+ threads.append((t, s))
+ for t, s in threads:
+ t.start()
+ s.shutdown()
+ for t, s in threads:
+ t.join()
+
def test_main():
if imp.lock_held():