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Fix profiling in Python 3.10 #259

merged 3 commits into from Sep 1, 2021

Fix profiling in Python 3.10 #259

merged 3 commits into from Sep 1, 2021


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@jamadden jamadden commented Aug 31, 2021

This required some additional state management and several new tests.

Fixes #256.

jamadden added 3 commits Aug 30, 2021
The cframe member was always being initialized from the PyThreadState's root_cframe, which doesn't properly have use_tracing set, so new greenlets didn't get tracing.

Here, we do exactly what CPython's ceval.c does and stack-allocate a new CFrame object in g_initialstub and copy the use_tracing value from the currently executing thread state.

This seems to solve the tracing issue, but further tests are needed; none of the existing tests failed with the broken behaviour. In addition to adding an example from #256, we need to test that the use_tracing flag properly propagates up and down when a profiler is set inside a greenlet, likewise I've only been testing switch, need to test throw, and need to test several variations on calling as a method, just a target function, an object assigned to a greenlet, etc.
This proves that propagating the tracer *upward* (to a parent greenlet) in Cpython 3.10 fails. However, 4287a40 did fix propagating it downward (to a new greenlet). Likely, propagating among sibling greenlets is also broken.
Because it's stack based, we need to store it separately.
@jamadden jamadden merged commit d70ab45 into master Sep 1, 2021
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@jamadden jamadden deleted the issue256 branch Sep 1, 2021
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