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/Modules/_xxsubinterpretersmodule.c b/Modules/_xxsubinterpretersmodule.c
index d758807..49d3b48 100644
--- a/Modules/_xxsubinterpretersmodule.c
+++ b/Modules/_xxsubinterpretersmodule.c
@@ -1759,8 +1759,13 @@
}
// Switch to interpreter.
- PyThreadState *tstate = PyInterpreterState_ThreadHead(interp);
- PyThreadState *save_tstate = PyThreadState_Swap(tstate);
+ PyThreadState *save_tstate = NULL;
+ if (interp != PyThreadState_Get()->interp) {
+ // XXX Using the "head" thread isn't strictly correct.
+ PyThreadState *tstate = PyInterpreterState_ThreadHead(interp);
+ // XXX Possible GILState issues?
+ save_tstate = PyThreadState_Swap(tstate);
+ }
// Run the script.
_sharedexception *exc = NULL;
@@ -2079,9 +2084,9 @@
}
// Create and initialize the new interpreter.
- PyThreadState *tstate, *save_tstate;
- save_tstate = PyThreadState_Swap(NULL);
- tstate = Py_NewInterpreter();
+ PyThreadState *save_tstate = PyThreadState_Swap(NULL);
+ // XXX Possible GILState issues?
+ PyThreadState *tstate = Py_NewInterpreter();
PyThreadState_Swap(save_tstate);
if (tstate == NULL) {
/* Since no new thread state was created, there is no exception to
@@ -2096,6 +2101,7 @@
return _get_id(tstate->interp);
error:
+ // XXX Possible GILState issues?
save_tstate = PyThreadState_Swap(tstate);
Py_EndInterpreter(tstate);
PyThreadState_Swap(save_tstate);
@@ -2146,9 +2152,9 @@
// Destroy the interpreter.
//PyInterpreterState_Delete(interp);
- PyThreadState *tstate, *save_tstate;
- tstate = PyInterpreterState_ThreadHead(interp);
- save_tstate = PyThreadState_Swap(tstate);
+ PyThreadState *tstate = PyInterpreterState_ThreadHead(interp);
+ // XXX Possible GILState issues?
+ PyThreadState *save_tstate = PyThreadState_Swap(tstate);
Py_EndInterpreter(tstate);
PyThreadState_Swap(save_tstate);