Issue #7978: socketserver now restarts the select() call when EINTR is returned.

This avoids crashing the server loop when a signal is received.
Patch by Jerzy Kozera.

Lib/test/test_socketserver.py

@@ -8,6 +8,8 @@ import os
 import select
 import signal
 import socket
+import select
+import errno
 import tempfile
 import unittest
 import socketserver
@@ -226,6 +228,38 @@ class SocketServerTest(unittest.TestCase):
                                 socketserver.DatagramRequestHandler,
                                 self.dgram_examine)
 
+    @contextlib.contextmanager
+    def mocked_select_module(self):
+        """Mocks the select.select() call to raise EINTR for first call"""
+        old_select = select.select
+
+        class MockSelect:
+            def __init__(self):
+                self.called = 0
+
+            def __call__(self, *args):
+                self.called += 1
+                if self.called == 1:
+                    # raise the exception on first call
+                    raise OSError(errno.EINTR, os.strerror(errno.EINTR))
+                else:
+                    # Return real select value for consecutive calls
+                    return old_select(*args)
+
+        select.select = MockSelect()
+        try:
+            yield select.select
+        finally:
+            select.select = old_select
+
+    def test_InterruptServerSelectCall(self):
+        with self.mocked_select_module() as mock_select:
+            pid = self.run_server(socketserver.TCPServer,
+                                  socketserver.StreamRequestHandler,
+                                  self.stream_examine)
+            # Make sure select was called again:
+            self.assertGreater(mock_select.called, 1)
+
     # Alas, on Linux (at least) recvfrom() doesn't return a meaningful
     # client address so this cannot work: