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devdanzin/instrumentation_offset_leak.md

Created March 18, 2026 10:06
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instrumentation.c: PyLong leaked per C API monitoring call
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instrumentation_offset_leak.md

instrumentation.c: PyLong leaked per C API monitoring call

Summary

capi_call_instrumentation (line 2609) creates offset_obj = PyLong_FromLong(offset) stored in args[2] but never calls Py_DECREF. Affects ~16 _PyMonitoring_Fire*Event C API functions. Unbounded memory growth in long-running apps using C monitoring.

Fix

Add Py_DECREF(args[2]) before return (for non-LINE events).

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