bpo-36368: Ignore SIGINT in SharedMemoryManager servers. (GH-12483)

Fix a bug crashing SharedMemoryManager instances in interactive sessions after
a Ctrl-C (KeyboardInterrupt) was sent.

Author: pierreglaser

Lib/multiprocessing/managers.py

@@ -17,6 +17,7 @@
 
 import sys
 import threading
+import signal
 import array
 import queue
 import time
@@ -596,6 +597,9 @@ def _run_server(cls, registry, address, authkey, serializer, writer,
         '''
         Create a server, report its address and run it
         '''
+        # bpo-36368: protect server process from KeyboardInterrupt signals
+        signal.signal(signal.SIGINT, signal.SIG_IGN)
+
         if initializer is not None:
             initializer(*initargs)
 

Lib/test/_test_multiprocessing.py

@@ -3734,6 +3734,30 @@ def test_shared_memory_across_processes(self):
 
         sms.close()
 
+    @unittest.skipIf(os.name != "posix", "not feasible in non-posix platforms")
+    def test_shared_memory_SharedMemoryServer_ignores_sigint(self):
+        # bpo-36368: protect SharedMemoryManager server process from
+        # KeyboardInterrupt signals.
+        smm = multiprocessing.managers.SharedMemoryManager()
+        smm.start()
+
+        # make sure the manager works properly at the beginning
+        sl = smm.ShareableList(range(10))
+
+        # the manager's server should ignore KeyboardInterrupt signals, and
+        # maintain its connection with the current process, and success when
+        # asked to deliver memory segments.
+        os.kill(smm._process.pid, signal.SIGINT)
+
+        sl2 = smm.ShareableList(range(10))
+
+        # test that the custom signal handler registered in the Manager does
+        # not affect signal handling in the parent process.
+        with self.assertRaises(KeyboardInterrupt):
+            os.kill(os.getpid(), signal.SIGINT)
+
+        smm.shutdown()
+
     def test_shared_memory_SharedMemoryManager_basics(self):
         smm1 = multiprocessing.managers.SharedMemoryManager()
         with self.assertRaises(ValueError):

Misc/NEWS.d/next/Library/2019-03-21-16-00-00.bpo-36368.zsRT1.rst

@@ -0,0 +1,2 @@
+Fix a bug crashing SharedMemoryManager instances in interactive sessions after
+a ctrl-c (KeyboardInterrupt) was sent