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gh-151436: Fix missing tstate->last_profiled_frame updates (#151437)
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Lines changed: 33 additions & 8 deletions

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‎Include/internal/pycore_interpframe.h‎

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Original file line numberDiff line numberDiff line change
@@ -287,6 +287,20 @@ _PyThreadState_GetFrame(PyThreadState *tstate)
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return _PyFrame_GetFirstComplete(tstate->current_frame);
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}
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// Update last_profiled_frame for remote profiler frame caching.
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// Only update if we're removing the exact frame that was last profiled.
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// This avoids corrupting the cache when transient frames (called and returned
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// between profiler samples) update last_profiled_frame to addresses the
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// profiler never saw.
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#define _PyThreadState_UpdateLastProfiledFrame(tstate, frame, previous) \
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do { \
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PyThreadState *tstate_ = (tstate); \
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_PyInterpreterFrame *frame_ = (frame); \
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if (tstate_->last_profiled_frame == frame_) { \
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tstate_->last_profiled_frame = (previous); \
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} \
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} while (0)
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/* For use by _PyFrame_GetFrameObject
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Do not call directly. */
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PyAPI_FUNC(PyFrameObject *)

‎Misc/NEWS.d/next/Library/2026-06-13-11-57-48.gh-issue-151436.UEDowO.rst‎

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@@ -0,0 +1,4 @@
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Fix skewed stack trackes in the Tachyon profiler when caching is enabled and
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when generators and coroutines are profiled, by updating
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``tstate->last_profiled_frame`` at every frame-removal site. The issue resulted
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in total erasure of some callers. Patch by Maurycy Pawłowski-Wieroński.

‎Modules/_testinternalcapi/test_cases.c.h‎

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‎Objects/genobject.c‎

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@@ -168,6 +168,7 @@ gen_clear_frame(PyGenObject *gen)
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{
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assert(FT_ATOMIC_LOAD_INT8_RELAXED(gen->gi_frame_state) == FRAME_CLEARED);
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_PyInterpreterFrame *frame = &gen->gi_iframe;
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_PyThreadState_UpdateLastProfiledFrame(_PyThreadState_GET(), frame, frame->previous);
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frame->previous = NULL;
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_PyFrame_ClearExceptCode(frame);
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_PyErr_ClearExcState(&gen->gi_exc_state);
@@ -681,6 +682,7 @@ _gen_throw(PyGenObject *gen, int close_on_genexit,
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'yield from' or awaiting on with 'await'. */
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ret = _gen_throw((PyGenObject *)yf, close_on_genexit,
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typ, val, tb);
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_PyThreadState_UpdateLastProfiledFrame(tstate, frame, prev);
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tstate->current_frame = prev;
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frame->previous = NULL;
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}
@@ -701,6 +703,7 @@ _gen_throw(PyGenObject *gen, int close_on_genexit,
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frame->previous = prev;
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tstate->current_frame = frame;
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ret = PyObject_CallFunctionObjArgs(meth, typ, val, tb, NULL);
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_PyThreadState_UpdateLastProfiledFrame(tstate, frame, prev);
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tstate->current_frame = prev;
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frame->previous = NULL;
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Py_DECREF(meth);

‎Python/bytecodes.c‎

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@@ -1860,6 +1860,7 @@ dummy_func(
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gen->gi_exc_state.previous_item = NULL;
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_Py_LeaveRecursiveCallPy(tstate);
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_PyInterpreterFrame *gen_frame = frame;
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_PyThreadState_UpdateLastProfiledFrame(tstate, gen_frame, gen_frame->previous);
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frame = tstate->current_frame = frame->previous;
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gen_frame->previous = NULL;
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((_PyThreadStateImpl *)tstate)->generator_return_kind = GENERATOR_YIELD;
@@ -5874,6 +5875,7 @@ dummy_func(
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gen_frame->owner = FRAME_OWNED_BY_GENERATOR;
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_Py_LeaveRecursiveCallPy(tstate);
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_PyInterpreterFrame *prev = frame->previous;
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_PyThreadState_UpdateLastProfiledFrame(tstate, frame, prev);
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_PyThreadState_PopFrame(tstate, frame);
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frame = tstate->current_frame = prev;
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LOAD_IP(frame->return_offset);

‎Python/ceval.c‎

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Original file line numberDiff line numberDiff line change
@@ -1974,15 +1974,8 @@ clear_gen_frame(PyThreadState *tstate, _PyInterpreterFrame * frame)
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void
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_PyEval_FrameClearAndPop(PyThreadState *tstate, _PyInterpreterFrame * frame)
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{
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// Update last_profiled_frame for remote profiler frame caching.
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// By this point, tstate->current_frame is already set to the parent frame.
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// Only update if we're popping the exact frame that was last profiled.
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// This avoids corrupting the cache when transient frames (called and returned
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// between profiler samples) update last_profiled_frame to addresses the
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// profiler never saw.
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if (tstate->last_profiled_frame != NULL && tstate->last_profiled_frame == frame) {
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tstate->last_profiled_frame = tstate->current_frame;
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}
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_PyThreadState_UpdateLastProfiledFrame(tstate, frame, tstate->current_frame);
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if (frame->owner == FRAME_OWNED_BY_THREAD) {
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clear_thread_frame(tstate, frame);
@@ -2008,6 +2001,7 @@ _PyEvalFramePushAndInit(PyThreadState *tstate, _PyStackRef func,
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_PyFrame_Initialize(tstate, frame, func, locals, code, 0, previous);
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if (initialize_locals(tstate, func_obj, frame->localsplus, args, argcount, kwnames)) {
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assert(frame->owner == FRAME_OWNED_BY_THREAD);
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_PyThreadState_UpdateLastProfiledFrame(tstate, frame, tstate->current_frame);
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clear_thread_frame(tstate, frame);
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return NULL;
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}

‎Python/executor_cases.c.h‎

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‎Python/generated_cases.c.h‎

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