gh-155109: Run tests exhausting the C stack with a limited C stack - #155120
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gh-155109: Run tests exhausting the C stack with a limited C stack#155120serhiy-storchaka wants to merge 3 commits into
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Add the @support.run_with_limited_c_stack() decorator which runs the test in a thread with a small C stack, so that the outcome does not depend on RLIMIT_STACK. Use it in tests which recurse to a fixed depth -- @support.skip_if_huge_c_stack() failed to skip them with a 16 MiB stack. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
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August 3, 2026 13:44
On platforms where the interpreter cannot query the thread stack size it assumes Py_C_STACK_SIZE (4 MiB), so a smaller thread stack crashes instead of raising RecursionError. Verified on illumos and OpenBSD: a 2 MiB stack dumps core, 8 MiB raises RecursionError. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
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@kulikjak, could you please test if this helps? |
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
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August 3, 2026 20:52
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Add the
@support.run_with_limited_c_stack(depth)decorator: it runs the test in a thread with an 8 MiB C stack, so that the outcome does not depend onRLIMIT_STACK. If the thread stack size cannot be limited, it falls back to the old behavior — run in the current thread and skip if the C stack is too large.Use it in tests which recurse to a fixed depth.
@support.skip_if_huge_c_stack()estimates the remaining stack in interpreter loop frames (~328 bytes), so it fails to skip tests which recurse with much smaller C frames (~100 bytes) — they fail with a 16 MiB stack. It is kept for tests with unbounded recursion and fortest_call.test_super_deep(), which needs a deep stack.Tested on Linux with 1, 8, 16, 32 and 512 MiB and unlimited stack limits, and on illumos and OpenBSD.
skip_if_huge_c_stackunderestimates available C recursion depth #155109