Commit Graph

3 Commits

Author SHA1 Message Date
Sam Gross 8dbfdb2957
gh-110481: Fix biased reference counting queue initialization. (#117271)
The biased reference counting queue must be initialized from the bound
(active) thread because it uses `_Py_ThreadId()` as the key in a hash
table.
2024-03-28 09:28:39 -04:00
Brett Simmers 0749244d13
gh-112175: Add `eval_breaker` to `PyThreadState` (#115194)
This change adds an `eval_breaker` field to `PyThreadState`. The primary
motivation is for performance in free-threaded builds: with thread-local eval
breakers, we can stop a specific thread (e.g., for an async exception) without
interrupting other threads.

The source of truth for the global instrumentation version is stored in the
`instrumentation_version` field in PyInterpreterState. Threads usually read the
version from their local `eval_breaker`, where it continues to be colocated
with the eval breaker bits.
2024-02-20 09:57:48 -05:00
Sam Gross a3af3cb4f4
gh-110481: Implement inter-thread queue for biased reference counting (#114824)
Biased reference counting maintains two refcount fields in each object:
`ob_ref_local` and `ob_ref_shared`. The true refcount is the sum of these two
fields. In some cases, when refcounting operations are split across threads,
the ob_ref_shared field can be negative (although the total refcount must be
at least zero). In this case, the thread that decremented the refcount
requests that the owning thread give up ownership and merge the refcount
fields.
2024-02-09 17:08:32 -05:00