There were a few thread-safety issues when profiling or tracing all
threads via PyEval_SetProfileAllThreads or PyEval_SetTraceAllThreads:
* The loop over thread states could crash if a thread exits concurrently
(in both the free threading and default build)
* The modification of `c_profilefunc` and `c_tracefunc` wasn't
thread-safe on the free threading build.
(cherry picked from commit a10152f8fd)
The free threading build uses QSBR to delay the freeing of dictionary
keys and list arrays when the objects are accessed by multiple threads
in order to allow concurrent reads to proceed with holding the object
lock. The requests are processed in batches to reduce execution
overhead, but for large memory blocks this can lead to excess memory
usage.
Take into account the size of the memory block when deciding when to
process QSBR requests.
Also track the amount of memory being held by QSBR for mimalloc pages.
Advance the write sequence if this memory exceeds a limit. Advancing
the sequence will allow it to be freed more quickly.
Process the held QSBR items from the "eval breaker", rather than from
`_PyMem_FreeDelayed()`. This gives a higher chance that the global read
sequence has advanced enough so that items can be freed.
(cherry picked from commit 113de8545f)
Co-authored-by: Neil Schemenauer <nas-github@arctrix.com>
Co-authored-by: Sam Gross <colesbury@gmail.com>
This approach eliminates the originally reported race. It also gets rid of the deadlock reported in gh-96071, so we can remove the workaround added then.
This is mostly a cherry-pick of 1c0a104 (AKA gh-126989). The difference is we add PyInterpreterState.threads_preallocated at the end of PyInterpreterState, instead of adding PyInterpreterState.threads.preallocated. That avoids ABI disruption.
When formatting the AST as a string, infinite values are replaced by
1e309, which evaluates to infinity. The initialization of this string
replacement was not thread-safe in the free threading build.
(cherry picked from commit 427dcf24de)
Revert the incremental GC in 3.13, since it's not clear that without further turning, the benefits outweigh the costs.
Co-authored-by: Adam Turner <9087854+AA-Turner@users.noreply.github.com>
