bpo-32604: Swap threads only if the interpreter is different. (gh-5783)
The CPython runtime assumes that there is a one-to-one relationship (for a given interpreter) between PyThreadState and OS threads. Sending and receiving on a channel in the same interpreter was causing crashes because of this (specifically due to a check in PyThreadState_Swap()). The solution is to not switch threads if the interpreter is the same.
(cherry picked from commit f53d9f2778a87bdd48eb9030f782a4ebf9e7622f)
Co-authored-by: Eric Snow <ericsnowcurrently@gmail.com>
diff --git a/Lib/test/test__xxsubinterpreters.py b/Lib/test/test__xxsubinterpreters.py
index d280270..397d359 100644
--- a/Lib/test/test__xxsubinterpreters.py
+++ b/Lib/test/test__xxsubinterpreters.py
@@ -3,6 +3,7 @@
import pickle
from textwrap import dedent, indent
import threading
+import time
import unittest
from test import support
@@ -1147,6 +1148,54 @@
self.assertEqual(obj, b'spam')
+ def test_send_recv_different_threads(self):
+ cid = interpreters.channel_create()
+
+ def f():
+ while True:
+ try:
+ obj = interpreters.channel_recv(cid)
+ break
+ except interpreters.ChannelEmptyError:
+ time.sleep(0.1)
+ interpreters.channel_send(cid, obj)
+ t = threading.Thread(target=f)
+ t.start()
+
+ interpreters.channel_send(cid, b'spam')
+ t.join()
+ obj = interpreters.channel_recv(cid)
+
+ self.assertEqual(obj, b'spam')
+
+ def test_send_recv_different_interpreters_and_threads(self):
+ cid = interpreters.channel_create()
+ id1 = interpreters.create()
+ out = None
+
+ def f():
+ nonlocal out
+ out = _run_output(id1, dedent(f"""
+ import time
+ import _xxsubinterpreters as _interpreters
+ while True:
+ try:
+ obj = _interpreters.channel_recv({int(cid)})
+ break
+ except _interpreters.ChannelEmptyError:
+ time.sleep(0.1)
+ assert(obj == b'spam')
+ _interpreters.channel_send({int(cid)}, b'eggs')
+ """))
+ t = threading.Thread(target=f)
+ t.start()
+
+ interpreters.channel_send(cid, b'spam')
+ t.join()
+ obj = interpreters.channel_recv(cid)
+
+ self.assertEqual(obj, b'eggs')
+
def test_send_not_found(self):
with self.assertRaises(interpreters.ChannelNotFoundError):
interpreters.channel_send(10, b'spam')