#Issue3088 in-progress: Race condition with instances of classes derived from threading.local:
When a thread touches such an object for the first time, a new thread-local __dict__ is created,
and the __init__ method is run.
But a thread switch can occur here; if the other thread touches the same object, it installs another
__dict__; when the first thread resumes, it updates the dictionary of the second...
This is the deep cause of the failures in test_multiprocessing involving "managers" objects.
Backport of r64601.
diff --git a/Modules/threadmodule.c b/Modules/threadmodule.c
index 036619a..2726045 100644
--- a/Modules/threadmodule.c
+++ b/Modules/threadmodule.c
@@ -294,7 +294,10 @@
}
}
- else if (self->dict != ldict) {
+
+ /* The call to tp_init above may have caused another thread to run.
+ Install our ldict again. */
+ if (self->dict != ldict) {
Py_CLEAR(self->dict);
Py_INCREF(ldict);
self->dict = ldict;