gh-140301: Fix memory leak in subinterpreter PyConfig cleanup #140303

ashm-dev · 2025-10-18T15:09:42Z

Issue: Memory leak in test_capi with subinterpreter creation #140301

ashm-dev · 2025-10-18T15:18:25Z

Before

Using random seed: 1222208301
0:00:00 load avg: 0.27 Run 1 test in parallel using 1 worker process
0:00:30 load avg: 1.41 running (1): test_capi (30.0 sec)
0:01:00 load avg: 2.65 running (1): test_capi (1 min)
0:01:30 load avg: 2.46 running (1): test_capi (1 min 30 sec)
0:02:00 load avg: 2.02 running (1): test_capi (2 min)
0:02:30 load avg: 1.62 running (1): test_capi (2 min 30 sec)
0:03:00 load avg: 1.34 running (1): test_capi (3 min)
0:03:30 load avg: 1.26 running (1): test_capi (3 min 30 sec)
0:04:00 load avg: 1.11 running (1): test_capi (4 min)
0:04:30 load avg: 1.07 running (1): test_capi (4 min 30 sec)
0:05:00 load avg: 0.99 running (1): test_capi (5 min)
0:05:11 load avg: 0.99 [1/1/1] test_capi worker non-zero exit code (Exit code 1)
beginning 10 repetitions. Showing number of leaks (. for 0 or less, X for 10 or more)
12345:67890
XX... .....
[445 refs, 0 blocks]

=================================================================
==825239==ERROR: LeakSanitizer: detected memory leaks

Direct leak of 521400 byte(s) in 5280 object(s) allocated from:
    #0 0x5fe80f021308 in malloc (/home/shamil/oss/cpython/main/python+0x9b3308) (BuildId: 8456de8e4761b446f6be29a8c19a9fb2137b4ff2)
    #1 0x5fe80f5e2323 in _PyMem_DebugRawAlloc /home/shamil/oss/cpython/main/Objects/obmalloc.c:2887:24
    #2 0x5fe80f5df34b in PyMem_RawMalloc /home/shamil/oss/cpython/main/Objects/obmalloc.c:1000:12
    #3 0x5fe80f5df34b in _PyMem_RawWcsdup /home/shamil/oss/cpython/main/Objects/obmalloc.c:1089:21
    #4 0x5fe80fae1ce5 in PyConfig_SetString /home/shamil/oss/cpython/main/Python/initconfig.c:1158:16
    #5 0x5fe80fae248c in _PyConfig_Copy /home/shamil/oss/cpython/main/Python/initconfig.c:1259:22
    #6 0x5fe80fb5c325 in new_interpreter /home/shamil/oss/cpython/main/Python/pylifecycle.c:2453:14
    #7 0x5fe80fb5be7a in Py_NewInterpreterFromConfig /home/shamil/oss/cpython/main/Python/pylifecycle.c:2521:12
    #8 0x6ffbaddbdff6 in run_in_subinterp_with_config /home/shamil/oss/cpython/main/./Modules/_testinternalcapi.c:1854:27
    #9 0x5fe80f57ac4a in cfunction_call /home/shamil/oss/cpython/main/Objects/methodobject.c:564:18
    #10 0x5fe80f3f06be in _PyObject_MakeTpCall /home/shamil/oss/cpython/main/Objects/call.c:242:18
    #11 0x5fe80f8cdbd5 in _PyEval_EvalFrameDefault /home/shamil/oss/cpython/main/Python/generated_cases.c.h:4021:35
    #12 0x5fe80f8b86b1 in _PyEval_Vector /home/shamil/oss/cpython/main/Python/ceval.c:2001:12
    #13 0x5fe80f400063 in _PyObject_VectorcallTstate /home/shamil/oss/cpython/main/./Include/internal/pycore_call.h:169:11
    #14 0x5fe80f3fc3dd in method_vectorcall /home/shamil/oss/cpython/main/Objects/classobject.c:95:18
    #15 0x5fe80f3f292b in _PyVectorcall_Call /home/shamil/oss/cpython/main/Objects/call.c:273:16
    #16 0x5fe80f8ecb70 in _PyEval_EvalFrameDefault /home/shamil/oss/cpython/main/Python/generated_cases.c.h:2616:32
    #17 0x5fe80f8b86b1 in _PyEval_Vector /home/shamil/oss/cpython/main/Python/ceval.c:2001:12
    #18 0x5fe80f3f015e in _PyObject_VectorcallDictTstate /home/shamil/oss/cpython/main/Objects/call.c:135:15
    #19 0x5fe80f3f3e2d in _PyObject_Call_Prepend /home/shamil/oss/cpython/main/Objects/call.c:504:24
    #20 0x5fe80f66cfe7 in call_method /home/shamil/oss/cpython/main/Objects/typeobject.c:3076:19
    #21 0x5fe80f3f06be in _PyObject_MakeTpCall /home/shamil/oss/cpython/main/Objects/call.c:242:18
    #22 0x5fe80f8cdbd5 in _PyEval_EvalFrameDefault /home/shamil/oss/cpython/main/Python/generated_cases.c.h:4021:35
    #23 0x5fe80f8b86b1 in _PyEval_Vector /home/shamil/oss/cpython/main/Python/ceval.c:2001:12
    #24 0x5fe80f400063 in _PyObject_VectorcallTstate /home/shamil/oss/cpython/main/./Include/internal/pycore_call.h:169:11
    #25 0x5fe80f3fc3dd in method_vectorcall /home/shamil/oss/cpython/main/Objects/classobject.c:95:18
    #26 0x5fe80f3f292b in _PyVectorcall_Call /home/shamil/oss/cpython/main/Objects/call.c:273:16
    #27 0x5fe80f8ecb70 in _PyEval_EvalFrameDefault /home/shamil/oss/cpython/main/Python/generated_cases.c.h:2616:32
    #28 0x5fe80f8b86b1 in _PyEval_Vector /home/shamil/oss/cpython/main/Python/ceval.c:2001:12
    #29 0x5fe80f3f015e in _PyObject_VectorcallDictTstate /home/shamil/oss/cpython/main/Objects/call.c:135:15
    #30 0x5fe80f3f3e2d in _PyObject_Call_Prepend /home/shamil/oss/cpython/main/Objects/call.c:504:24

Direct leak of 84480 byte(s) in 1650 object(s) allocated from:
    #0 0x5fe80f021308 in malloc (/home/shamil/oss/cpython/main/python+0x9b3308) (BuildId: 8456de8e4761b446f6be29a8c19a9fb2137b4ff2)
    #1 0x5fe80f5e2323 in _PyMem_DebugRawAlloc /home/shamil/oss/cpython/main/Objects/obmalloc.c:2887:24
    #2 0x5fe80fadcdd0 in _PyWideStringList_CopyEx /home/shamil/oss/cpython/main/Python/initconfig.c:701:22
    #3 0x5fe80fae2352 in _PyWideStringList_Copy /home/shamil/oss/cpython/main/Python/initconfig.c:731:12
    #4 0x5fe80fae2352 in _PyConfig_Copy /home/shamil/oss/cpython/main/Python/initconfig.c:1267:17
    #5 0x5fe80fb5c325 in new_interpreter /home/shamil/oss/cpython/main/Python/pylifecycle.c:2453:14
    #6 0x5fe80fb5be7a in Py_NewInterpreterFromConfig /home/shamil/oss/cpython/main/Python/pylifecycle.c:2521:12
    #7 0x6ffbaddbdff6 in run_in_subinterp_with_config /home/shamil/oss/cpython/main/./Modules/_testinternalcapi.c:1854:27
    #8 0x5fe80f57ac4a in cfunction_call /home/shamil/oss/cpython/main/Objects/methodobject.c:564:18
    #9 0x5fe80f3f06be in _PyObject_MakeTpCall /home/shamil/oss/cpython/main/Objects/call.c:242:18
    #10 0x5fe80f8cdbd5 in _PyEval_EvalFrameDefault /home/shamil/oss/cpython/main/Python/generated_cases.c.h:4021:35
    #11 0x5fe80f8b86b1 in _PyEval_Vector /home/shamil/oss/cpython/main/Python/ceval.c:2001:12
    #12 0x5fe80f400063 in _PyObject_VectorcallTstate /home/shamil/oss/cpython/main/./Include/internal/pycore_call.h:169:11
    #13 0x5fe80f3fc3dd in method_vectorcall /home/shamil/oss/cpython/main/Objects/classobject.c:95:18
    #14 0x5fe80f3f292b in _PyVectorcall_Call /home/shamil/oss/cpython/main/Objects/call.c:273:16
    #15 0x5fe80f8ecb70 in _PyEval_EvalFrameDefault /home/shamil/oss/cpython/main/Python/generated_cases.c.h:2616:32
    #16 0x5fe80f8b86b1 in _PyEval_Vector /home/shamil/oss/cpython/main/Python/ceval.c:2001:12
    #17 0x5fe80f3f015e in _PyObject_VectorcallDictTstate /home/shamil/oss/cpython/main/Objects/call.c:135:15
    #18 0x5fe80f3f3e2d in _PyObject_Call_Prepend /home/shamil/oss/cpython/main/Objects/call.c:504:24
    #19 0x5fe80f66cfe7 in call_method /home/shamil/oss/cpython/main/Objects/typeobject.c:3076:19
    #20 0x5fe80f3f06be in _PyObject_MakeTpCall /home/shamil/oss/cpython/main/Objects/call.c:242:18
    #21 0x5fe80f8cdbd5 in _PyEval_EvalFrameDefault /home/shamil/oss/cpython/main/Python/generated_cases.c.h:4021:35
    #22 0x5fe80f8b86b1 in _PyEval_Vector /home/shamil/oss/cpython/main/Python/ceval.c:2001:12
    #23 0x5fe80f400063 in _PyObject_VectorcallTstate /home/shamil/oss/cpython/main/./Include/internal/pycore_call.h:169:11
    #24 0x5fe80f3fc3dd in method_vectorcall /home/shamil/oss/cpython/main/Objects/classobject.c:95:18
    #25 0x5fe80f3f292b in _PyVectorcall_Call /home/shamil/oss/cpython/main/Objects/call.c:273:16
    #26 0x5fe80f8ecb70 in _PyEval_EvalFrameDefault /home/shamil/oss/cpython/main/Python/generated_cases.c.h:2616:32
    #27 0x5fe80f8b86b1 in _PyEval_Vector /home/shamil/oss/cpython/main/Python/ceval.c:2001:12
    #28 0x5fe80f3f015e in _PyObject_VectorcallDictTstate /home/shamil/oss/cpython/main/Objects/call.c:135:15
    #29 0x5fe80f3f3e2d in _PyObject_Call_Prepend /home/shamil/oss/cpython/main/Objects/call.c:504:24
    #30 0x5fe80f66cfe7 in call_method /home/shamil/oss/cpython/main/Objects/typeobject.c:3076:19

Indirect leak of 2163480 byte(s) in 5610 object(s) allocated from:
    #0 0x5fe80f021308 in malloc (/home/shamil/oss/cpython/main/python+0x9b3308) (BuildId: 8456de8e4761b446f6be29a8c19a9fb2137b4ff2)
    #1 0x5fe80f5e2323 in _PyMem_DebugRawAlloc /home/shamil/oss/cpython/main/Objects/obmalloc.c:2887:24
    #2 0x5fe80f5df34b in PyMem_RawMalloc /home/shamil/oss/cpython/main/Objects/obmalloc.c:1000:12
    #3 0x5fe80f5df34b in _PyMem_RawWcsdup /home/shamil/oss/cpython/main/Objects/obmalloc.c:1089:21
    #4 0x5fe80fadcf1e in _PyWideStringList_CopyEx /home/shamil/oss/cpython/main/Python/initconfig.c:713:20
    #5 0x5fe80fae2352 in _PyWideStringList_Copy /home/shamil/oss/cpython/main/Python/initconfig.c:731:12
    #6 0x5fe80fae2352 in _PyConfig_Copy /home/shamil/oss/cpython/main/Python/initconfig.c:1267:17
    #7 0x5fe80fb5c325 in new_interpreter /home/shamil/oss/cpython/main/Python/pylifecycle.c:2453:14
    #8 0x5fe80fb5be7a in Py_NewInterpreterFromConfig /home/shamil/oss/cpython/main/Python/pylifecycle.c:2521:12
    #9 0x6ffbaddbdff6 in run_in_subinterp_with_config /home/shamil/oss/cpython/main/./Modules/_testinternalcapi.c:1854:27
    #10 0x5fe80f57ac4a in cfunction_call /home/shamil/oss/cpython/main/Objects/methodobject.c:564:18
    #11 0x5fe80f3f06be in _PyObject_MakeTpCall /home/shamil/oss/cpython/main/Objects/call.c:242:18
    #12 0x5fe80f8cdbd5 in _PyEval_EvalFrameDefault /home/shamil/oss/cpython/main/Python/generated_cases.c.h:4021:35
    #13 0x5fe80f8b86b1 in _PyEval_Vector /home/shamil/oss/cpython/main/Python/ceval.c:2001:12
    #14 0x5fe80f400063 in _PyObject_VectorcallTstate /home/shamil/oss/cpython/main/./Include/internal/pycore_call.h:169:11
    #15 0x5fe80f3fc3dd in method_vectorcall /home/shamil/oss/cpython/main/Objects/classobject.c:95:18
    #16 0x5fe80f3f292b in _PyVectorcall_Call /home/shamil/oss/cpython/main/Objects/call.c:273:16
    #17 0x5fe80f8ecb70 in _PyEval_EvalFrameDefault /home/shamil/oss/cpython/main/Python/generated_cases.c.h:2616:32
    #18 0x5fe80f8b86b1 in _PyEval_Vector /home/shamil/oss/cpython/main/Python/ceval.c:2001:12
    #19 0x5fe80f3f015e in _PyObject_VectorcallDictTstate /home/shamil/oss/cpython/main/Objects/call.c:135:15
    #20 0x5fe80f3f3e2d in _PyObject_Call_Prepend /home/shamil/oss/cpython/main/Objects/call.c:504:24
    #21 0x5fe80f66cfe7 in call_method /home/shamil/oss/cpython/main/Objects/typeobject.c:3076:19
    #22 0x5fe80f3f06be in _PyObject_MakeTpCall /home/shamil/oss/cpython/main/Objects/call.c:242:18
    #23 0x5fe80f8cdbd5 in _PyEval_EvalFrameDefault /home/shamil/oss/cpython/main/Python/generated_cases.c.h:4021:35
    #24 0x5fe80f8b86b1 in _PyEval_Vector /home/shamil/oss/cpython/main/Python/ceval.c:2001:12
    #25 0x5fe80f400063 in _PyObject_VectorcallTstate /home/shamil/oss/cpython/main/./Include/internal/pycore_call.h:169:11
    #26 0x5fe80f3fc3dd in method_vectorcall /home/shamil/oss/cpython/main/Objects/classobject.c:95:18
    #27 0x5fe80f3f292b in _PyVectorcall_Call /home/shamil/oss/cpython/main/Objects/call.c:273:16
    #28 0x5fe80f8ecb70 in _PyEval_EvalFrameDefault /home/shamil/oss/cpython/main/Python/generated_cases.c.h:2616:32
    #29 0x5fe80f8b86b1 in _PyEval_Vector /home/shamil/oss/cpython/main/Python/ceval.c:2001:12
    #30 0x5fe80f3f015e in _PyObject_VectorcallDictTstate /home/shamil/oss/cpython/main/Objects/call.c:135:15
    #31 0x5fe80f3f3e2d in _PyObject_Call_Prepend /home/shamil/oss/cpython/main/Objects/call.c:504:24

SUMMARY: AddressSanitizer: 2769360 byte(s) leaked in 12540 allocation(s).

== Tests result: FAILURE ==

1 test failed:
    test_capi

Total duration: 5 min 11 sec
Total tests: run=0
Total test files: run=1/1 failed=1
Result: FAILURE
[0 refs, 0 blocks]

After

Using random seed: 749864916
0:00:00 load avg: 0.94 Run 1 test in parallel using 1 worker process
0:00:30 load avg: 0.95 running (1): test_capi (30.0 sec)
0:01:00 load avg: 1.09 running (1): test_capi (1 min)
0:01:30 load avg: 1.22 running (1): test_capi (1 min 30 sec)
0:02:00 load avg: 1.24 running (1): test_capi (2 min)
0:02:30 load avg: 1.41 running (1): test_capi (2 min 30 sec)
0:03:00 load avg: 1.24 running (1): test_capi (3 min)
0:03:30 load avg: 1.20 running (1): test_capi (3 min 30 sec)
0:04:00 load avg: 1.30 running (1): test_capi (4 min)
0:04:30 load avg: 1.68 running (1): test_capi (4 min 30 sec)
0:05:00 load avg: 1.49 running (1): test_capi (5 min)
0:05:18 load avg: 1.23 [1/1] test_capi passed (5 min 18 sec)
beginning 10 repetitions. Showing number of leaks (. for 0 or less, X for 10 or more)
12345:67890
XX... .....
[445 refs, 0 blocks]

== Tests result: SUCCESS ==

1 test OK.

Total duration: 5 min 18 sec
Total tests: run=1,172 skipped=140
Total test files: run=1/1
Result: SUCCESS
[0 refs, 0 blocks]

Python/pylifecycle.c

Also removes some redundant calls.

Misc/NEWS.d/next/Core_and_Builtins/2025-10-18-18-08-36.gh-issue-140301.m-2HxC.rst

…e-140301.m-2HxC.rst Co-authored-by: Kumar Aditya <[email protected]>

miss-islington-app · 2025-10-20T09:29:26Z

Thanks @ashm-dev for the PR, and @kumaraditya303 for merging it 🌮🎉.. I'm working now to backport this PR to: 3.13, 3.14.
🐍🍒⛏🤖

…pythonGH-140303) (cherry picked from commit a615fb4) Co-authored-by: Shamil <[email protected]> Co-authored-by: Kumar Aditya <[email protected]>

miss-islington-app · 2025-10-20T09:29:33Z

Sorry, @ashm-dev and @kumaraditya303, I could not cleanly backport this to 3.13 due to a conflict.
Please backport using cherry_picker on command line.

cherry_picker a615fb49c948902a982c3256899507abcc9f9bc8 3.13

bedevere-app · 2025-10-20T09:29:40Z

GH-140360 is a backport of this pull request to the 3.14 branch.

GH-140303) (#140360) gh-140301: Fix memory leak in subinterpreter `PyConfig` cleanup (GH-140303) (cherry picked from commit a615fb4) Co-authored-by: Shamil <[email protected]> Co-authored-by: Kumar Aditya <[email protected]>

StanFromIreland · 2025-10-27T15:12:59Z

@ashm-dev Can you do the backport please? If you do not know how, let me know and I can do it.

ashm-dev · 2025-10-27T15:19:13Z

@StanFromIreland OK, I'll do it!)

…python#140303) Co-authored-by: Kumar Aditya <[email protected]> (cherry picked from commit a615fb4)

…eanup (pythonGH-140303)

…cleanup (pythonGH-140303) (cherry picked from commit a615fb4) Co-authored-by: Shamil <[email protected]> Co-authored-by: Kumar Aditya <[email protected]>

bedevere-app · 2025-10-27T19:17:05Z

GH-140684 is a backport of this pull request to the 3.13 branch.

…H-140303) (#140684) [3.13] gh-140301: Fix memory leak in subinterpreter `PyConfig` cleanup (GH-140303) (cherry picked from commit a615fb4) Co-authored-by: Kumar Aditya <[email protected]>

…python#140303) Co-authored-by: Kumar Aditya <[email protected]>

pythongh-140301: Fix memory leak in subinterpreter PyConfig cleanup

4adb87e

ashm-dev requested review from ZeroIntensity and ericsnowcurrently as code owners October 18, 2025 15:09

bedevere-app bot added the awaiting review label Oct 18, 2025

bedevere-app bot mentioned this pull request Oct 18, 2025

Memory leak in test_capi with subinterpreter creation #140301

Closed

kumaraditya303 reviewed Oct 18, 2025

View reviewed changes

Python/pylifecycle.c Outdated Show resolved Hide resolved

Cleanup PyConfig in interpreter deletion

3cc27d2

Also removes some redundant calls.

ashm-dev requested a review from kumaraditya303 October 18, 2025 15:56

kumaraditya303 reviewed Oct 20, 2025

View reviewed changes

Misc/NEWS.d/next/Core_and_Builtins/2025-10-18-18-08-36.gh-issue-140301.m-2HxC.rst Outdated Show resolved Hide resolved

Update Misc/NEWS.d/next/Core_and_Builtins/2025-10-18-18-08-36.gh-issu…

9b09079

…e-140301.m-2HxC.rst Co-authored-by: Kumar Aditya <[email protected]>

ashm-dev requested a review from kumaraditya303 October 20, 2025 09:04

kumaraditya303 approved these changes Oct 20, 2025

View reviewed changes

bedevere-app bot added awaiting merge and removed awaiting review labels Oct 20, 2025

kumaraditya303 added topic-subinterpreters needs backport to 3.14 bugs and security fixes labels Oct 20, 2025

kumaraditya303 enabled auto-merge (squash) October 20, 2025 09:22

kumaraditya303 added the needs backport to 3.13 bugs and security fixes label Oct 20, 2025

kumaraditya303 merged commit a615fb4 into python:main Oct 20, 2025
55 checks passed

bedevere-app bot removed the awaiting merge label Oct 20, 2025

miss-islington-app bot assigned kumaraditya303 Oct 20, 2025

bedevere-app bot removed the needs backport to 3.14 bugs and security fixes label Oct 20, 2025

ashm-dev deleted the test_capi_leak branch October 20, 2025 09:32

StanFromIreland assigned ashm-dev and unassigned kumaraditya303 Oct 27, 2025

ashm-dev added a commit to ashm-dev/cpython that referenced this pull request Oct 27, 2025

pythongh-140301: Fix memory leak in subinterpreter PyConfig cleanup (…

c38ad5e

…python#140303) Co-authored-by: Kumar Aditya <[email protected]> (cherry picked from commit a615fb4)

ashm-dev added a commit to ashm-dev/cpython that referenced this pull request Oct 27, 2025

[3.13] pythongh-140301: Fix memory leak in subinterpreter PyConfig cl…

affa9be

…eanup (pythonGH-140303)

bedevere-app bot removed the needs backport to 3.13 bugs and security fixes label Oct 27, 2025

StanFromIreland pushed a commit to StanFromIreland/cpython that referenced this pull request Dec 6, 2025

pythongh-140301: Fix memory leak in subinterpreter PyConfig cleanup (…

459785b

…python#140303) Co-authored-by: Kumar Aditya <[email protected]>

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