| msg339079 - (view) |
Author: STINNER Victor (vstinner) *  |
Date: 2019-03-28 23:01 |
| When Python is built in debug mode, PyObject gets 2 new fields: _ob_prev and _ob_next. These fields change the offset of following fields in the PyObject structure and so breaks the ABI. I propose to modify the debug build (Py_DEBUG) to not imply Py_TRACE_REFS anymore. Antoine Pitrou proposed this idea when the C API was discussed to get a stable ABI. Another more radical idea is to completely remove Py_TRACE_REFS special build. |
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| msg339080 - (view) |
Author: STINNER Victor (vstinner) * |
Date: 2019-03-28 23:07 |
| > Another more radical idea is to completely remove Py_TRACE_REFS special build. I wrote PR 12614 to implement this idea. I wrote it to see which code depends on it: commit 63509498761a0e7f72585a8cd7df325ea2abd1b2 (HEAD -> remove_trace_refs, origin/remove_trace_refs) Author: Victor Stinner <vstinner@redhat.com> Date: Thu Mar 28 23:26:58 2019 +0100 WIP: bpo-36465: Remove Py_TRACE_REFS special build Remove _ob_prev and _ob_next fields of PyObject when Python is compiled in debug mode to make debug ABI closer to the release ABI. Remove: * sys.getobjects() * PYTHONDUMPREFS environment variable * _PyCoreConfig.dump_refs * PyObject._ob_prev and PyObject._ob_next fields * _PyObject_HEAD_EXTRA and _PyObject_EXTRA_INIT macros * _Py_AddToAllObjects() * _Py_PrintReferenceAddresses() * _Py_PrintReferences() * _Py_ForgetReference(op) is replaced with _Py_INC_TPFREES(op) I never used PYTHONDUMPREFS. I just tried in Python 3.7: Python does crash with this option... so this option doesn't sound popuplar. Otherwise, many users would complain. $ PYTHONDUMPREFS=1 python3.7-dbg -c pass ... 0x7f7eae14aa90 [1] 'Thread-local dummy' 0x7f7eae19b448 [1] (<class '_thread._localdummy'>, <class 'object'>) 0x7f7eae14aa30 [1] {'__doc__': 'Thread-local dummy'} 0x7f7eae1356d8 [1] (<class 'object'>,) 0x7d0940 [2] <class '_thread._localdummy'> 0x7f7eae120d58 [1] Segmentation fault (core dumped) I never used sys.getobjects() neither, but I can imagine that someone might want to use for very specific needs. So maybe it's safer to not immediately remove the feature. At least, a deprecation period would be needed. I suggest to reject PR 12614 and not remove Py_TRACE_REFS. |
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| msg339081 - (view) |
Author: STINNER Victor (vstinner) * |
Date: 2019-03-28 23:17 |
| PR 12615 changes Py_DEBUG to no longer imply Py_TRACE_REFS. IMHO it's a more reasonable approach. I'm not sure if it's enough to magically get exactly the same ABI than Python built in release mode. |
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| msg340746 - (view) |
Author: STINNER Victor (vstinner) * |
Date: 2019-04-23 23:09 |
| Since my goal here is to support a C extension compiled in release mode on a Python compiled in debug mode, Py_TRACE_REFS should be a new separated ABI since it modify Py_INCREF/Py_DECREF. Maybe a new configure option should be added to opt-in for Py_TRACE_REFS and add "t" (T stands for Trace references) to SOABI. |
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| msg340750 - (view) |
Author: STINNER Victor (vstinner) * |
Date: 2019-04-24 00:51 |
| I started a thread on python-dev to discuss this issue: "[Python-Dev] Use C extensions compiled in release mode on a Python compiled in debug mode" https://mail.python.org/pipermail/python-dev/2019-April/157178.html It's a follow-up of my previous thread: "[Python-Dev] No longer enable Py_TRACE_REFS by default in debug build" https://mail.python.org/pipermail/python-dev/2019-April/157015.html |
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| msg340812 - (view) |
Author: STINNER Victor (vstinner) * |
Date: 2019-04-24 22:56 |
| New changeset f4e4703e746067d6630410408d414b11003334d6 by Victor Stinner in branch 'master': bpo-36465: Make release and debug ABI compatible (GH-12615) https://github.com/python/cpython/commit/f4e4703e746067d6630410408d414b11003334d6 |
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| msg340813 - (view) |
Author: STINNER Victor (vstinner) * |
Date: 2019-04-24 23:46 |
| New changeset 235e7b2b0d937ba8b4a9172aa72206187e3e1f54 by Victor Stinner in branch 'master': bpo-36465: Fix test_regrtest on Windows (GH-12945) https://github.com/python/cpython/commit/235e7b2b0d937ba8b4a9172aa72206187e3e1f54 |
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| msg362126 - (view) |
Author: STINNER Victor (vstinner) * |
Date: 2020-02-17 09:18 |
| New changeset a7847590f07655e794d7c62130aea245a110acef by Hai Shi in branch 'master': bpo-36465: Update doc of init_config.rst (GH-18520) https://github.com/python/cpython/commit/a7847590f07655e794d7c62130aea245a110acef |
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| msg390064 - (view) |
Author: STINNER Victor (vstinner) * |
Date: 2021-04-02 13:45 |
| New changeset 3359cab038968935b40344fad7c30d211f9692e4 by Victor Stinner in branch 'master': bpo-43688: Support the limited C API in debug mode (GH-25131) https://github.com/python/cpython/commit/3359cab038968935b40344fad7c30d211f9692e4 |
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