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GH-100892: Fix race in clearing threading.local #100922

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Merged
kumaraditya303 merged 5 commits into from
Jan 11, 2023
Merged

GH-100892: Fix race in clearing threading.local #100922

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cd526b1
make local_clear thread-safe
kumaraditya303 Jan 10, 2023
49fc195
📜🤖 Added by blurb_it.
blurb-it[bot] Jan 10, 2023
d8399dd
add a test
kumaraditya303 Jan 10, 2023
ad9f8fd
fix formatting
kumaraditya303 Jan 10, 2023
5d39f6a
Merge branch 'main' into tstate
kumaraditya303 Jan 11, 2023
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make local_clear thread-safe
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@kumaraditya303
kumaraditya303 committed Jan 10, 2023
commit cd526b1a1668a9c3e42d351b01c4f5410f4de9b2
30 changes: 20 additions & 10 deletions Modules/_threadmodule.c
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Original file line number Diff line number Diff line change
Expand Up @@ -839,6 +839,11 @@ local_traverse(localobject *self, visitproc visit, void *arg)
return 0;
}
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#define HEAD_LOCK(runtime) \
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PyThread_acquire_lock((runtime)->interpreters.mutex, WAIT_LOCK)
#define HEAD_UNLOCK(runtime) \
PyThread_release_lock((runtime)->interpreters.mutex)

static int
local_clear(localobject *self)
{
Expand All @@ -849,18 +854,23 @@ local_clear(localobject *self)
/* Remove all strong references to dummies from the thread states */
if (self->key) {
PyInterpreterState *interp = _PyInterpreterState_GET();
_PyRuntimeState *runtime = &_PyRuntime;
HEAD_LOCK(runtime);
PyThreadState *tstate = PyInterpreterState_ThreadHead(interp);
for(; tstate; tstate = PyThreadState_Next(tstate)) {
if (tstate->dict == NULL) {
continue;
}
PyObject *v = _PyDict_Pop(tstate->dict, self->key, Py_None);
if (v != NULL) {
Py_DECREF(v);
}
else {
PyErr_Clear();
HEAD_UNLOCK(runtime);
while (tstate) {
if (tstate->dict) {
PyObject *v = _PyDict_Pop(tstate->dict, self->key, Py_None);
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if (v != NULL) {
Py_DECREF(v);
}
else {
PyErr_Clear();
}
}
HEAD_LOCK(runtime);
tstate = PyThreadState_Next(tstate);
HEAD_UNLOCK(runtime);
}
}
return 0;
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