[Python-checkins] bpo-22087: Fix Policy.get_event_loop() to detect fork (GH-7208)
Yury Selivanov
webhook-mailer at python.org
Tue May 29 15:38:10 EDT 2018
https://github.com/python/cpython/commit/5d97b7bcc19496617bf8c448d2f149cc28c73bc7
commit: 5d97b7bcc19496617bf8c448d2f149cc28c73bc7
branch: master
author: Yury Selivanov <yury at magic.io>
committer: GitHub <noreply at github.com>
date: 2018-05-29T15:38:07-04:00
summary:
bpo-22087: Fix Policy.get_event_loop() to detect fork (GH-7208)
Original patch by Dan O'Reilly.
files:
A Misc/NEWS.d/next/Library/2018-05-29-12-06-54.bpo-22087.uv7_Y6.rst
M Lib/asyncio/events.py
M Lib/test/test_asyncio/test_unix_events.py
diff --git a/Lib/asyncio/events.py b/Lib/asyncio/events.py
index 40946bbf6529..68dc25e1e8be 100644
--- a/Lib/asyncio/events.py
+++ b/Lib/asyncio/events.py
@@ -625,16 +625,23 @@ class BaseDefaultEventLoopPolicy(AbstractEventLoopPolicy):
class _Local(threading.local):
_loop = None
+ _pid = None
_set_called = False
def __init__(self):
self._local = self._Local()
+ self._local._pid = os.getpid()
def get_event_loop(self):
"""Get the event loop.
This may be None or an instance of EventLoop.
"""
+ if self._local._pid != os.getpid():
+ # If we detect we're in a child process forked by multiprocessing,
+ # we reset self._local so that we'll get a new event loop.
+ self._local = self._Local()
+
if (self._local._loop is None and
not self._local._set_called and
isinstance(threading.current_thread(), threading._MainThread)):
diff --git a/Lib/test/test_asyncio/test_unix_events.py b/Lib/test/test_asyncio/test_unix_events.py
index a01efedf66d9..1bc2d8658d8a 100644
--- a/Lib/test/test_asyncio/test_unix_events.py
+++ b/Lib/test/test_asyncio/test_unix_events.py
@@ -13,6 +13,7 @@
import tempfile
import threading
import unittest
+import multiprocessing
from unittest import mock
from test import support
@@ -1804,6 +1805,37 @@ def create_watcher(self):
return asyncio.FastChildWatcher()
+class ForkedProcessTests(unittest.TestCase):
+ def setUp(self):
+ self.parent_loop = asyncio.SelectorEventLoop()
+ asyncio.set_event_loop(self.parent_loop)
+ self.ctx = multiprocessing.get_context("fork")
+
+ def tearDown(self):
+ self.parent_loop.close()
+
+ def _check_loops_not_equal(self, old_loop):
+ loop = asyncio.get_event_loop()
+ if loop is old_loop:
+ raise RuntimeError("Child process inherited parent's event loop")
+
+ try:
+ val = loop.run_until_complete(asyncio.sleep(0.05, result=42))
+ if val != 42:
+ raise RuntimeError("new event loop does not work")
+ finally:
+ loop.close()
+
+ sys.exit(loop is old_loop)
+
+ def test_new_loop_in_child(self):
+ p = self.ctx.Process(target=self._check_loops_not_equal,
+ args=(self.parent_loop,))
+ p.start()
+ p.join()
+ self.assertEqual(p.exitcode, 0)
+
+
class PolicyTests(unittest.TestCase):
def create_policy(self):
diff --git a/Misc/NEWS.d/next/Library/2018-05-29-12-06-54.bpo-22087.uv7_Y6.rst b/Misc/NEWS.d/next/Library/2018-05-29-12-06-54.bpo-22087.uv7_Y6.rst
new file mode 100644
index 000000000000..92127cd57a91
--- /dev/null
+++ b/Misc/NEWS.d/next/Library/2018-05-29-12-06-54.bpo-22087.uv7_Y6.rst
@@ -0,0 +1,3 @@
+Fix Policy.get_event_loop() to detect fork and return a new loop.
+
+Original patch by Dan O'Reilly.
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