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gh-140358: Bring back elapsed time and unreachable count to gc debug output #140359

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Merged
merged 14 commits into from
Oct 20, 2025
+43 −0
Merged

gh-140358: Bring back elapsed time and unreachable count to gc debug output #140359

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c2bf816
Bring back elapsed time and unreachable count to gc debug
pgdr Oct 19, 2025
da96551
Add blurb for gc-elapsed-time
pgdr Oct 20, 2025
d6a6054
Remove accidentally added linebrak
pgdr Oct 20, 2025
38c1212
Initialize now under `if (gcstate->debug ...)` cond
pgdr Oct 20, 2025
56c6eab
Fix backticks in blurb
pgdr Oct 20, 2025
2a37cd4
Fix unreachable = collected + uncollectable.
pgdr Oct 20, 2025
456a38a
Rename now and endtime to t1,t2
pgdr Oct 20, 2025
60129b6
Fix mistake
pgdr Oct 20, 2025
5db0a98
Use PerfCounter instead of monotonic
pgdr Oct 20, 2025
d54283b
Add test to check debug info written to stderr in gc
pgdr Oct 20, 2025
3527d42
Use assertRegex for check debug stats
pgdr Oct 20, 2025
9a4523b
Add decorator for skip if gil disabled
pgdr Oct 20, 2025
4a18a47
Make lines shorter in test
pgdr Oct 20, 2025
48ca72a
Address review comments
pgdr Oct 20, 2025
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15 changes: 15 additions & 0 deletions Python/gc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -10,6 +10,7 @@
#include "pycore_interpframe.h" // _PyFrame_GetLocalsArray()
#include "pycore_object_alloc.h" // _PyObject_MallocWithType()
#include "pycore_pystate.h" // _PyThreadState_GET()
#include "pycore_time.h" // _PyTime_MonotonicRaw()
#include "pycore_tuple.h" // _PyTuple_MaybeUntrack()
#include "pycore_weakref.h" // _PyWeakref_ClearRef()

Expand Down Expand Up @@ -1816,6 +1817,7 @@ gc_collect_region(PyThreadState *tstate,
/* Collect statistics on uncollectable objects found and print
* debugging information. */
Py_ssize_t n = 0;

for (gc = GC_NEXT(&finalizers); gc != &finalizers; gc = GC_NEXT(gc)) {
n++;
if (gcstate->debug & _PyGC_DEBUG_UNCOLLECTABLE)
Expand Down Expand Up @@ -2066,6 +2068,8 @@ _PyGC_Collect(PyThreadState *tstate, int generation, _PyGC_Reason reason)
{
GCState *gcstate = &tstate->interp->gc;
assert(tstate->current_frame == NULL || tstate->current_frame->stackpointer != NULL);
PyTime_t now;
(void)PyTime_MonotonicRaw(&now);

int expected = 0;
if (!_Py_atomic_compare_exchange_int(&gcstate->collecting, &expected, 1)) {
Expand Down Expand Up @@ -2115,6 +2119,17 @@ _PyGC_Collect(PyThreadState *tstate, int generation, _PyGC_Reason reason)
#endif
validate_spaces(gcstate);
_Py_atomic_store_int(&gcstate->collecting, 0);

if (gcstate->debug & _PyGC_DEBUG_STATS) {
PyTime_t endtime;
(void)PyTime_MonotonicRaw(&endtime);
double d = PyTime_AsSecondsDouble(endtime - now);
PySys_WriteStderr(
"gc: done, %zd unreachable, %zd uncollectable, %.4fs elapsed\n",
stats.collected, stats.uncollectable, d
);
}

return stats.uncollectable + stats.collected;
}

Expand Down
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