ReuseFRAME_OWNED_BY_INTERPRETER

python · pablogsal · Dec 7, 2025 · Nov 24, 2025 · Nov 25, 2025 · Nov 25, 2025
commit e14dc8ebb19d3c6c1bd60995266149fe3b2697cc
diff --git a/Include/internal/pycore_interpframe_structs.h b/Include/internal/pycore_interpframe_structs.h
@@ -24,7 +24,6 @@ enum _frameowner {
     FRAME_OWNED_BY_GENERATOR = 1,
     FRAME_OWNED_BY_FRAME_OBJECT = 2,
     FRAME_OWNED_BY_INTERPRETER = 3,
-    FRAME_OWNED_BY_THREAD_STATE = 4,  /* Sentinel base frame in thread state */
 };
 
 struct _PyInterpreterFrame {

@@ -116,7 +116,7 @@ instruction which cleans up the shim frame and returns.
 Each thread state contains an embedded `_PyInterpreterFrame` called the "base frame"
 that serves as a sentinel at the bottom of the frame stack. This frame is allocated
 in `_PyThreadStateImpl` (the internal extension of `PyThreadState`) and initialized
-when the thread state is created. The `owner` field is set to `FRAME_OWNED_BY_THREAD_STATE`.
+when the thread state is created. The `owner` field is set to `FRAME_OWNED_BY_INTERPRETER`.
 
 External profilers and sampling tools can validate that they have successfully unwound
 the complete call stack by checking that the frame chain terminates at the base frame.
@@ -135,7 +135,7 @@ See the initialization in `new_threadstate()` in [Python/pystate.c](../Python/py
 
 External profilers should read `tstate->base_frame` before walking the stack, then
 walk from `tstate->current_frame` following `frame->previous` pointers until reaching
-a frame with `owner == FRAME_OWNED_BY_THREAD_STATE`. After the walk, verify that the
+a frame with `owner == FRAME_OWNED_BY_INTERPRETER`. After the walk, verify that the
 last frame address matches `base_frame`. If not, discard the sample as incomplete
 since the frame chain may have been in an inconsistent state due to concurrent updates.
 

diff --git a/Misc/NEWS.d/next/Core_and_Builtins/2025-11-24-16-07-57.gh-issue-138122.m3EF9E.rst b/Misc/NEWS.d/next/Core_and_Builtins/2025-11-24-16-07-57.gh-issue-138122.m3EF9E.rst
@@ -1,6 +1,6 @@
 Add incomplete sample detection to prevent corrupted profiling data. Each
 thread state now contains an embedded base frame (sentinel at the bottom of
-the frame stack) with owner type ``FRAME_OWNED_BY_THREAD_STATE``. The profiler
+the frame stack) with owner type ``FRAME_OWNED_BY_INTERPRETER``. The profiler
 validates that stack unwinding terminates at this sentinel frame. Samples that
 fail to reach the base frame (due to race conditions, memory corruption, or
 other errors) are now rejected rather than being included as spurious data.
@@ -156,11 +156,7 @@ is_frame_valid(
 
     char owner = GET_MEMBER(char, frame, unwinder->debug_offsets.interpreter_frame.owner);
     if (owner == FRAME_OWNED_BY_INTERPRETER) {
-        return 0;  // C frame
-    }
-
-    if (owner == FRAME_OWNED_BY_THREAD_STATE) {
-        return 0;  // Sentinel base frame - end of stack
+        return 0;  // C frame or sentinel base frame
     }
 
     if (owner != FRAME_OWNED_BY_GENERATOR && owner != FRAME_OWNED_BY_THREAD) {

@@ -1493,7 +1493,7 @@ init_threadstate(_PyThreadStateImpl *_tstate,
     _tstate->base_frame.instr_ptr = NULL;
     _tstate->base_frame.stackpointer = _tstate->base_frame.localsplus;
     _tstate->base_frame.return_offset = 0;
-    _tstate->base_frame.owner = FRAME_OWNED_BY_THREAD_STATE;
+    _tstate->base_frame.owner = FRAME_OWNED_BY_INTERPRETER;
     _tstate->base_frame.visited = 0;
 #ifdef Py_DEBUG
     _tstate->base_frame.lltrace = 0;

diff --git a/Python/traceback.c b/Python/traceback.c
@@ -1035,8 +1035,7 @@ _Py_DumpWideString(int fd, wchar_t *str)
 static int
 dump_frame(int fd, _PyInterpreterFrame *frame)
 {
-    if (frame->owner == FRAME_OWNED_BY_INTERPRETER ||
-        frame->owner == FRAME_OWNED_BY_THREAD_STATE) {
+    if (frame->owner == FRAME_OWNED_BY_INTERPRETER) {
         /* Ignore trampoline frames and base frame sentinel */
         return 0;
     }