https://github.com/python/cpython/commit/274a26cca8e3d2f4de0283d4acbc80be391a5f6a
commit: 274a26cca8e3d2f4de0283d4acbc80be391a5f6a
branch: main
author: Pablo Galindo Salgado <[email protected]>
committer: pablogsal <[email protected]>
date: 2025-11-17T16:32:08Z
summary:
gh-135953: Simplify GC markers in the tachyon profiler (#141666)
files:
M Lib/profiling/sampling/gecko_collector.py
M Lib/test/test_profiling/test_sampling_profiler.py
M Modules/_remote_debugging_module.c
diff --git a/Lib/profiling/sampling/gecko_collector.py
b/Lib/profiling/sampling/gecko_collector.py
index 6c6700f113083e..21c427b7c862a4 100644
--- a/Lib/profiling/sampling/gecko_collector.py
+++ b/Lib/profiling/sampling/gecko_collector.py
@@ -141,7 +141,6 @@ def collect(self, stack_frames):
for thread_info in interpreter_info.threads:
frames = thread_info.frame_info
tid = thread_info.thread_id
- gc_collecting = thread_info.gc_collecting
# Initialize thread if needed
if tid not in self.threads:
@@ -197,16 +196,16 @@ def collect(self, stack_frames):
self._add_marker(tid, "Waiting for GIL",
self.gil_wait_start.pop(tid),
current_time, CATEGORY_GIL)
- # Track GC events - attribute to all threads that hold the GIL
during GC
- # (GC is interpreter-wide but runs on whichever thread(s) have
the GIL)
- # If GIL switches during GC, multiple threads will get GC
markers
- if gc_collecting and has_gil:
- # Start GC marker if not already started for this thread
+ # Track GC events by detecting <GC> frames in the stack trace
+ # This leverages the improved GC frame tracking from commit
336366fd7ca
+ # which precisely identifies the thread that initiated GC
collection
+ has_gc_frame = any(frame[2] == "<GC>" for frame in frames)
+ if has_gc_frame:
+ # This thread initiated GC collection
if tid not in self.gc_start_per_thread:
self.gc_start_per_thread[tid] = current_time
elif tid in self.gc_start_per_thread:
- # End GC marker if it was running for this thread
- # (either GC finished or thread lost GIL)
+ # End GC marker when no more GC frames are detected
self._add_marker(tid, "GC Collecting",
self.gc_start_per_thread.pop(tid),
current_time, CATEGORY_GC)
diff --git a/Lib/test/test_profiling/test_sampling_profiler.py
b/Lib/test/test_profiling/test_sampling_profiler.py
index a24dbb55cd7bab..2d00173c22c419 100644
--- a/Lib/test/test_profiling/test_sampling_profiler.py
+++ b/Lib/test/test_profiling/test_sampling_profiler.py
@@ -63,14 +63,13 @@ def __repr__(self):
class MockThreadInfo:
"""Mock ThreadInfo for testing since the real one isn't accessible."""
- def __init__(self, thread_id, frame_info, status=0, gc_collecting=False):
# Default to THREAD_STATE_RUNNING (0)
+ def __init__(self, thread_id, frame_info, status=0): # Default to
THREAD_STATE_RUNNING (0)
self.thread_id = thread_id
self.frame_info = frame_info
self.status = status
- self.gc_collecting = gc_collecting
def __repr__(self):
- return f"MockThreadInfo(thread_id={self.thread_id},
frame_info={self.frame_info}, status={self.status},
gc_collecting={self.gc_collecting})"
+ return f"MockThreadInfo(thread_id={self.thread_id},
frame_info={self.frame_info}, status={self.status})"
class MockInterpreterInfo:
@@ -2742,7 +2741,6 @@ def __init__(self, thread_id, frame_info, status):
self.thread_id = thread_id
self.frame_info = frame_info
self.status = status
- self.gc_collecting = False
# Create test data: active thread (HAS_GIL | ON_CPU), idle thread
(neither), and another active thread
ACTIVE_STATUS = THREAD_STATUS_HAS_GIL | THREAD_STATUS_ON_CPU # Has
GIL and on CPU
diff --git a/Modules/_remote_debugging_module.c
b/Modules/_remote_debugging_module.c
index 51b3c6bac02b54..6544e3a0ce6876 100644
--- a/Modules/_remote_debugging_module.c
+++ b/Modules/_remote_debugging_module.c
@@ -186,7 +186,6 @@ static PyStructSequence_Field ThreadInfo_fields[] = {
{"thread_id", "Thread ID"},
{"status", "Thread status (flags: HAS_GIL, ON_CPU, UNKNOWN or legacy
enum)"},
{"frame_info", "Frame information"},
- {"gc_collecting", "Whether GC is collecting (interpreter-level)"},
{NULL}
};
@@ -2726,8 +2725,6 @@ unwind_stack_for_thread(
goto error;
}
- int gc_collecting = GET_MEMBER(int, gc_state,
unwinder->debug_offsets.gc.collecting);
-
// Calculate thread status using flags (always)
int status_flags = 0;
@@ -2827,18 +2824,10 @@ unwind_stack_for_thread(
goto error;
}
- PyObject *py_gc_collecting = PyBool_FromLong(gc_collecting);
- if (py_gc_collecting == NULL) {
- set_exception_cause(unwinder, PyExc_RuntimeError, "Failed to create
gc_collecting");
- Py_DECREF(py_status);
- goto error;
- }
-
// py_status contains status flags (bitfield)
PyStructSequence_SetItem(result, 0, thread_id);
PyStructSequence_SetItem(result, 1, py_status); // Steals reference
PyStructSequence_SetItem(result, 2, frame_info); // Steals reference
- PyStructSequence_SetItem(result, 3, py_gc_collecting); // Steals reference
cleanup_stack_chunks(&chunks);
return result;
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