This combines most _PyStackRef functions and macros between the free
threaded and default builds.
- Remove Py_TAG_DEFERRED (same as Py_TAG_REFCNT)
- Remove PyStackRef_IsDeferred (same as !PyStackRef_RefcountOnObject)
Co-Authored-By: Paul Ross <apaulross@gmail.com>
Co-Authored-By: Carol Willing <carolcode@willingconsulting.com>
Co-Authored-By: Hugo van Kemenade <hugovk@users.noreply.github.com>
Co-Authored-By: Ezio Melotti <ezio.melotti@gmail.com>
Co-Authored-By: Adam Turner <9087854+aa-turner@users.noreply.github.com>
This PR implements frame caching in the RemoteUnwinder class to significantly reduce memory reads when profiling remote processes with deep call stacks.
When cache_frames=True, the unwinder stores the frame chain from each sample and reuses unchanged portions in subsequent samples. Since most profiling samples capture similar call stacks (especially the parent frames), this optimization avoids repeatedly reading the same frame data from the target process.
The implementation adds a last_profiled_frame field to the thread state that tracks where the previous sample stopped. On the next sample, if the current frame chain reaches this marker, the cached frames from that point onward are reused instead of being re-read from remote memory.
The sampling profiler now enables frame caching by default.
Only raises if the stack pointer is both below the limit *and* above the stack base.
This prevents false positives for user-space threads, as the stack pointer will be outside those bounds
if the stack has been swapped.
Fix a bug caused by the garbage collector clearing weakrefs too early. The
weakrefs in the ``tp_subclasses`` dictionary are needed in order to correctly
invalidate type caches (for example, by calling ``PyType_Modified()``).
Clearing weakrefs before calling finalizers causes the caches to not be
correctly invalidated. That can cause crashes since the caches can refer to
invalid objects. Defer the clearing of weakrefs without callbacks until after
finalizers are executed.
fix duplicated sections in frames.md file
In the frames.md file at InternalDocs, change the first
duplicated title to Specials, and remove unnecessary content
under the Specials section.
* Mark almost all reachable objects before doing collection phase
* Add stats for objects marked
* Visit new frames before each increment
* Update docs
* Clearer calculation of work to do.
