Issue #6056: Make multiprocessing use setblocking(True) on the sockets it uses.

Original patch by J Derek Wilson.

Lib/multiprocessing/connection.py

@@ -497,6 +497,8 @@ if sys.platform != 'win32':
         '''
         if duplex:
             s1, s2 = socket.socketpair()
+            s1.setblocking(True)
+            s2.setblocking(True)
             c1 = Connection(s1.detach())
             c2 = Connection(s2.detach())
         else:
@@ -561,6 +563,7 @@ class SocketListener(object):
             if os.name == 'posix':
                 self._socket.setsockopt(socket.SOL_SOCKET,
                                         socket.SO_REUSEADDR, 1)
+            self._socket.setblocking(True)
             self._socket.bind(address)
             self._socket.listen(backlog)
             self._address = self._socket.getsockname()
@@ -579,6 +582,7 @@ class SocketListener(object):
 
     def accept(self):
         s, self._last_accepted = self._socket.accept()
+        s.setblocking(True)
         return Connection(s.detach())
 
     def close(self):
@@ -593,6 +597,7 @@ def SocketClient(address):
     '''
     family = address_type(address)
     with socket.socket( getattr(socket, family) ) as s:
+        s.setblocking(True)
         s.connect(address)
         return Connection(s.detach())
 

Lib/test/test_multiprocessing.py

@@ -3312,9 +3312,43 @@ class TestFlags(unittest.TestCase):
         child_flags, grandchild_flags = json.loads(data.decode('ascii'))
         self.assertEqual(child_flags, grandchild_flags)
 
+#
+# Test interaction with socket timeouts - see Issue #6056
+#
+
+class TestTimeouts(unittest.TestCase):
+    @classmethod
+    def _test_timeout(cls, child, address):
+        time.sleep(1)
+        child.send(123)
+        child.close()
+        conn = multiprocessing.connection.Client(address)
+        conn.send(456)
+        conn.close()
+
+    def test_timeout(self):
+        old_timeout = socket.getdefaulttimeout()
+        try:
+            socket.setdefaulttimeout(0.1)
+            parent, child = multiprocessing.Pipe(duplex=True)
+            l = multiprocessing.connection.Listener(family='AF_INET')
+            p = multiprocessing.Process(target=self._test_timeout,
+                                        args=(child, l.address))
+            p.start()
+            child.close()
+            self.assertEqual(parent.recv(), 123)
+            parent.close()
+            conn = l.accept()
+            self.assertEqual(conn.recv(), 456)
+            conn.close()
+            l.close()
+            p.join(10)
+        finally:
+            socket.setdefaulttimeout(old_timeout)
+
 testcases_other = [OtherTest, TestInvalidHandle, TestInitializers,
                    TestStdinBadfiledescriptor, TestWait, TestInvalidFamily,
-                   TestFlags]
+                   TestFlags, TestTimeouts]
 
 #
 #

Misc/ACKS

@@ -1130,6 +1130,7 @@ John Williams
 Sue Williams
 Frank Willison
 Greg V. Wilson
+J Derek Wilson
 Jody Winston
 Collin Winter
 Dik Winter

Misc/NEWS

@@ -55,6 +55,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #6056: Make multiprocessing use setblocking(True) on the
+  sockets it uses.  Original patch by J Derek Wilson.
+
 - Issue #15364: Fix sysconfig.get_config_var('srcdir') to be an
   absolute path.