The add_const() function in flowgraph.c uses a linear search over the
consts list to find the index of a constant. After gh-126835 moved
constant folding from the AST optimizer to the CFG optimizer, this
function is now called N times for N inner tuple elements during
fold_tuple_of_constants(), resulting in O(N²) total time.
Fix by maintaining an auxiliary _Py_hashtable_t that maps object
pointers to their indices in the consts list, providing O(1) lookup.
For a file with 100,000 constant 2-tuples:
- Before: 10.38s (add_const occupies 83.76% of CPU time)
- After: 1.48s
Improve `hash()` builtin docstring with caveats.
Mention its return type and that the value can be expected to change between
processes (hash randomization).
Why? The `hash` builtin gets reached for and used by a lot of people whether it
is the right tool or not. IDEs surface docstrings and people use pydoc and
`help(hash)`.
* Replaces ad-hoc logic for ending traces with a simple inequality: `fitness < exit_quality`
* Fitness starts high and is reduced for branches, backward edges, calls and trace length
* Exit quality reflect how good a spot that instruction is to end a trace. Closing a loop is very, specializable instructions are very low and the others in between.
_PyRawMutex_UnlockSlow CAS-removes the waiter from the list and then
calls _PySemaphore_Wakeup, with no handshake. If _PySemaphore_Wait
returns Py_PARK_INTR, the waiter can destroy its stack-allocated
semaphore before the unlocker's Wakeup runs, causing a fatal error from
ReleaseSemaphore / sem_post.
Loop in _PyRawMutex_LockSlow until _PySemaphore_Wait returns Py_PARK_OK,
which is only signalled when a matching Wakeup has been observed.
Also include GetLastError() and the handle in the Windows fatal messages
in _PySemaphore_Init, _PySemaphore_Wait, and _PySemaphore_Wakeup to make
similar races easier to diagnose in the future.
* Make the `PY_UNWIND` monitoring event available as a code-local
event to allow trapping on function exit events when an exception
bubbles up. This complements the PY_RETURN event by allowing to
catch any function exit event.
* Allow `PY_UNWIND` to be `DISABLE`d; disabling it disables the event for the whole code object.
* Do the above for `PY_THROW`, `RAISE`, `EXCEPTION_HANDLED`, and `RERAISE` events.
Forbid marshalling recursive code, slice and frozendict objects which
cannot be correctly unmarshalled.
Reject invalid marshal data produced by marshalling recursive frozendict
objects which was previously incorrectly unmarshalled.
Add multiple tests for recursive data structures.
Fix AArch64 multi-instruction constants and relocations
* Elimates rendundant orr xN, xN, 0xffff after 16 or 32 bit loads
* Merges adrp (21rx) and ldr (12) relocations into single 33rx relocation, when safe to do so.
* Add FOR_ITER_VIRTUAL to specialize FOR_ITER for virtual iterators
* Add GET_ITER_SELF to specialize GET_ITER for iterators (including generators)
* Add GET_ITER_VIRTUAL to specialize GET_ITER for iterables as virtual iterators
* Add new (internal) _tp_iteritem function slot to PyTypeObject
* Put limited RESUME at start of genexpr for free-threading. Fix up exception handling in genexpr
Ensure function annotations are returned in order of definition
Previously, when getting type annotations of a function, normal
arguments were returned before positional-only ones in the dictionary.
Since `functools.singledispatch` relies on this ordering being correct
to dispatch based on the type of the first argument, this issue was
causing incorrect registrations for functions with positional-only
arguments.
This commit updates how annotations are generated so that
positional-only arguments are generated and added to the dictionary
before normal arguments.
## Summary
- Move the `runtime->initialized = 1` store from before `site.py` import to the end of `init_interp_main()`, so `Py_IsInitialized()` only returns true after initialization has fully completed
- Access `initialized` and `core_initialized` through new inline accessors using acquire/release atomics, to also protect from data race undefined behavior
- `PySys_AddAuditHook()` now uses the accessor, so with the flag move it correctly skips audit hook invocation during all init phases (matching the documented "after runtime initialization" behavior) ... We could argue that running these earlier would be good even if the intent was never explicitly expressed, but that'd be its own issue.
## Motivation
`Py_IsInitialized()` returned 1 while `Py_InitializeEx()` was still running — specifically, before `site.py` had been imported. See https://github.com/PyO3/pyo3/issues/5900 where a second thread could acquire the GIL and start executing Python with an incomplete `sys.path` because `site.py` hadn't finished.
The flag was also a plain `int` with no atomic operations, making concurrent reads a C-standard data race, though unlikely to manifest.
## Regression test:
The added test properly fails on `main` with `ERROR: Py_IsInitialized() was true during site import`.
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Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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