The free-threaded GC now visits interpreter stacks to keep objects
that use deferred reference counting alive.
Interpreter frames are zero initialized in the free-threaded GC so
that the GC doesn't see garbage data. This is a temporary measure
until stack spilling around escaping calls is implemented.
Co-authored-by: Ken Jin <kenjin@python.org>
As of 529a160 (gh-118204), building with HAVE_DYNAMIC_LOADING stopped working. This is a minimal fix just to get builds working again. There are actually a number of long-standing deficiencies with HAVE_DYNAMIC_LOADING builds that need to be resolved separately.
This replaces `_PyList_FromArraySteal` with `_PyList_FromStackRefSteal`.
It's functionally equivalent, but takes a `_PyStackRef` array instead of
an array of `PyObject` pointers.
Co-authored-by: Ken Jin <kenjin@python.org>
`BUILD_SET` should use a borrow instead of a steal. The cleanup in `_DO_CALL`
`CONVERSION_FAILED` was incorrect.
Co-authored-by: Ken Jin <kenjin@python.org>
We were not properly accounting for interpreter memory leaks at
shutdown and had two sources of leaks:
* Objects that use deferred reference counting and were reachable via
static types outlive the final GC. We now disable deferred reference
counting on all objects if we are calling the GC due to interpreter
shutdown.
* `_PyMem_FreeDelayed` did not properly check for interpreter shutdown
so we had some memory blocks that were enqueued to be freed, but
never actually freed.
* `_PyType_FinalizeIdPool` wasn't called at interpreter shutdown.
Fix _PyArg_UnpackKeywordsWithVararg for the case when argument for
positional-or-keyword parameter is passed by keyword.
There was only one such case in the stdlib -- the TypeVar constructor.
This automatically spills the results from `_PyStackRef_FromPyObjectNew`
to the in-memory stack so that the deferred references are visible to
the GC before we make any possibly escaping call.
Co-authored-by: Ken Jin <kenjin@python.org>
Fix PyEval_GetLocals() to avoid SystemError ("bad argument to
internal function"). Don't redefine the 'ret' variable in the if
block.
Add an unit test on PyEval_GetLocals().
The free-threaded build partially stores heap type reference counts in
distributed manner in per-thread arrays. This avoids reference count
contention when creating or destroying instances.
Co-authored-by: Ken Jin <kenjin@python.org>
Add ENTER_RECURSIVE and LEAVE_RECURSIVE macros in ast.c, ast_opt.c and
symtable.c. Remove VISIT_QUIT macro in symtable.c.
The current recursion depth counter only needs to be updated during
normal execution -- all functions should just return an error code
if an error occurs.
* gh-122188: Move magic number to its own file
* Add versionadded directive
* Do work in C
* Integrate launcher.c
* Make _pyc_magic_number private
* Remove metadata
* Move sys.implementation -> _imp
* Modernize comment
* Move _RAW_MAGIC_NUMBER to the C side as well
* _pyc_magic_number -> pyc_magic_number
* Remove unused import
* Update docs
* Apply suggestions from code review
Co-authored-by: Eric Snow <ericsnowcurrently@gmail.com>
* Fix typo in tests
---------
Co-authored-by: Eric Snow <ericsnowcurrently@gmail.com>
The adaptive counter doesn't do anything currently in the free-threaded
build and TSan reports a data race due to concurrent modifications to
the counter.
* Use compensated summation for complex sums with floating-point items.
This amends #121176.
* sum() specializations for floats and complexes now use
PyLong_AsDouble() instead of PyLong_AsLongAndOverflow() and
compensated summation as well.
In the free-threaded build, we need to lock pending->mutex when clearing
the handling_thread in order not to race with a concurrent
make_pending_calls in the same interpreter.
This combines and updates our freelist handling to use a consistent
implementation. Objects in the freelist are linked together using the
first word of memory block.
If configured with freelists disabled, these operations are essentially
no-ops.
* Reject uop definitions that declare values as 'unused' that are already cached by prior uops
* Track which variables are defined and only load from memory when needed
* Support explicit `flush` in macro definitions.
* Make sure stack is flushed in where needed.
We should maintain the invariant that a zero `ob_tid` implies the
refcount fields are merged.
* Move the assignment in `_Py_MergeZeroLocalRefcount` to immediately
before the refcount merge.
* Update `_PyTrash_thread_destroy_chain` to set `ob_ref_shared` to
`_Py_REF_MERGED` when setting `ob_tid` to zero.
Also check this invariant with assertions in the GC in debug builds.
That uncovered a bug when running out of memory during GC.
* The result has type Py_ssize_t, not intptr_t.
* Type cast between unsigned and signdet integer types should be explicit.
* Downcasting should be explicit.
* Fix integer overflow check in sum().
The change in gh-118157 (b2cd54a) should have also updated clear_singlephase_extension() but didn't. We fix that here. Note that clear_singlephase_extension() (AKA _PyImport_ClearExtension()) is only used in tests.
The `_PySeqLock_EndRead` function needs an acquire fence to ensure that
the load of the sequence happens after any loads within the read side
critical section. The missing fence can trigger bugs on macOS arm64.
Additionally, we need a release fence in `_PySeqLock_LockWrite` to
ensure that the sequence update is visible before any modifications to
the cache entry.
The tracemalloc_tracebacks hash table has traceback keys and NULL
values, but its destructors do not reflect this -- key_destroy_func is
NULL while value_destroy_func is raw_free. Swap these to free the
traceback keys instead.
Fix warnings when using -Wimplicit-fallthrough compiler flag.
Annotate explicitly "fall through" switch cases with a new
_Py_FALLTHROUGH macro which uses __attribute__((fallthrough)) if
available. Replace "fall through" comments with _Py_FALLTHROUGH.
Add _Py__has_attribute() macro. No longer define __has_attribute()
macro if it's not defined. Move also _Py__has_builtin() at the top
of pyport.h.
Co-Authored-By: Nikita Sobolev <mail@sobolevn.me>
This change makes things a little less painful for some users. It also fixes a failing assert (gh-120765), by making sure all subinterpreters are destroyed before the main interpreter. As part of that, we make sure Py_Finalize() always runs with the main interpreter active.
This PR sets up tagged pointers for CPython.
The general idea is to create a separate struct _PyStackRef for everything on the evaluation stack to store the bits. This forces the C compiler to warn us if we try to cast things or pull things out of the struct directly.
Only for free threading: We tag the low bit if something is deferred - that means we skip incref and decref operations on it. This behavior may change in the future if Mark's plans to defer all objects in the interpreter loop pans out.
This implies a strict stack reference discipline is required. ALL incref and decref operations on stackrefs must use the stackref variants. It is unsafe to untag something then do normal incref/decref ops on it.
The new incref and decref variants are called dup and close. They mimic a "handle" API operating on these stackrefs.
Please read Include/internal/pycore_stackref.h for more information!
---------
Co-authored-by: Mark Shannon <9448417+markshannon@users.noreply.github.com>
This makes the following macros public as part of the non-limited C-API for
locking a single object or two objects at once.
* `Py_BEGIN_CRITICAL_SECTION(op)` / `Py_END_CRITICAL_SECTION()`
* `Py_BEGIN_CRITICAL_SECTION2(a, b)` / `Py_END_CRITICAL_SECTION2()`
The supporting functions and structs used by the macros are also exposed for
cases where C macros are not available.
* Add an InternalDocs file describing how interning should work and how to use it.
* Add internal functions to *explicitly* request what kind of interning is done:
- `_PyUnicode_InternMortal`
- `_PyUnicode_InternImmortal`
- `_PyUnicode_InternStatic`
* Switch uses of `PyUnicode_InternInPlace` to those.
* Disallow using `_Py_SetImmortal` on strings directly.
You should use `_PyUnicode_InternImmortal` instead:
- Strings should be interned before immortalization, otherwise you're possibly
interning a immortalizing copy.
- `_Py_SetImmortal` doesn't handle the `SSTATE_INTERNED_MORTAL` to
`SSTATE_INTERNED_IMMORTAL` update, and those flags can't be changed in
backports, as they are now part of public API and version-specific ABI.
* Add private `_only_immortal` argument for `sys.getunicodeinternedsize`, used in refleak test machinery.
* Make sure the statically allocated string singletons are unique. This means these sets are now disjoint:
- `_Py_ID`
- `_Py_STR` (including the empty string)
- one-character latin-1 singletons
Now, when you intern a singleton, that exact singleton will be interned.
* Add a `_Py_LATIN1_CHR` macro, use it instead of `_Py_ID`/`_Py_STR` for one-character latin-1 singletons everywhere (including Clinic).
* Intern `_Py_STR` singletons at startup.
* For free-threaded builds, intern `_Py_LATIN1_CHR` singletons at startup.
* Beef up the tests. Cover internal details (marked with `@cpython_only`).
* Add lots of assertions
Co-Authored-By: Eric Snow <ericsnowcurrently@gmail.com>
In gh-120009 I used an atexit hook to finalize the _datetime module's static types at interpreter shutdown. However, atexit hooks are executed very early in finalization, which is a problem in the few cases where a subclass of one of those static types is still alive until the final GC collection. The static builtin types don't have this probably because they are finalized toward the end, after the final GC collection. To avoid the problem for _datetime, I have applied a similar approach here.
Also, credit goes to @mgorny and @neonene for the new tests.
FYI, I would have liked to take a slightly cleaner approach with managed static types, but wanted to get a smaller fix in first for the sake of backporting. I'll circle back to the cleaner approach with a future change on the main branch.
This adds a `_PyRecursiveMutex` type based on `PyMutex` and uses that
for the import lock. This fixes some data races in the free-threaded
build and generally simplifies the import lock code.
The `_PyThreadState_Bind()` function is called before the first
`PyEval_AcquireThread()` so it's not synchronized with the stop the
world GC. We had a race where `gc_visit_heaps()` might visit a thread's
heap while it's being initialized.
Use a simple atomic int to avoid visiting heaps for threads that are not
yet fully initialized (i.e., before `tstate_mimalloc_bind()` is called).
The race was reproducible by running:
`python Lib/test/test_importlib/partial/pool_in_threads.py`.
We make use of the same mechanism that we use for the static builtin types. This required a few tweaks.
The relevant code could use some cleanup but I opted to avoid the significant churn in this change. I'll tackle that separately.
This change is the final piece needed to make _datetime support multiple interpreters. I've updated the module slot accordingly.
The free-threaded build currently immortalizes objects that use deferred
reference counting (see gh-117783). This typically happens once the
first non-main thread is created, but the behavior can be suppressed for
tests, in subinterpreters, or during a compile() call.
This fixes a race condition involving the tracking of whether the
behavior is suppressed.
Only call `gc_restore_tid()` from stop-the-world contexts.
`worklist_pop()` can be called while other threads are running, so use a
relaxed atomic to modify `ob_tid`.
* Add docs for new APIs
* Add soft-deprecation notices
* Add What's New porting entries
* Update comments referencing `PyFrame_LocalsToFast()` to mention the proxy instead
* Other related cleanups found when looking for refs to the deprecated APIs
Support non-dict globals in LOAD_FROM_DICT_OR_GLOBALS
The implementation basically copies LOAD_GLOBAL. Possibly it could be deduplicated,
but that seems like it may get hairy since the two operations have different operands.
This is important to fix in 3.14 for PEP 649, but it's a bug in earlier versions too,
and we should backport to 3.13 and 3.12 if possible.
Release the GIL before calling `_Py_qsbr_unregister`.
The deadlock could occur when the GIL was enabled at runtime. The
`_Py_qsbr_unregister` call might block while holding the GIL because the
thread state was not active, but the GIL was still held.
Make sure that `gilstate_counter` is not zero in when calling
`PyThreadState_Clear()`. A destructor called from `PyThreadState_Clear()` may
call back into `PyGILState_Ensure()` and `PyGILState_Release()`. If
`gilstate_counter` is zero, it will try to create a new thread state before
the current active thread state is destroyed, leading to an assertion failure
or crash.
* gh-119118: Fix performance regression in tokenize module
- Cache line object to avoid creating a Unicode object
for all of the tokens in the same line.
- Speed up byte offset to column offset conversion by using the
smallest buffer possible to measure the difference.
Co-authored-by: Pablo Galindo <pablogsal@gmail.com>
The fix in gh-119561 introduced an assertion that doesn't hold true if any of the three new test extension modules are loaded more than once. This is fine normally but breaks if the new test_check_state_first() is run more than once, which happens for refleak checking and with the regrtest --forever flag. We fix that here by clearing each of the three modules after loading them. We also tweak a check in _modules_by_index_check().
The assertion was added in gh-118532 but was based on the invalid assumption that PyState_FindModule() would only be called with an already-initialized module def. I've added a test to make sure we don't make that assumption again.
`drop_gil()` assumes that its caller is attached, which means that the current
thread holds the GIL if and only if the GIL is enabled, and the enabled-state
of the GIL won't change. This isn't true, though, because `detach_thread()`
calls `_PyEval_ReleaseLock()` after detaching and
`_PyThreadState_DeleteCurrent()` calls it after removing the current thread
from consideration for stop-the-world requests (effectively detaching it).
Fix this by remembering whether or not a thread acquired the GIL when it last
attached, in `PyThreadState._status.holds_gil`, and check this in `drop_gil()`
instead of `gil->enabled`.
This fixes a crash in `test_multiprocessing_pool_circular_import()`, so I've
reenabled it.
_PyArg_Parser holds static global data generated for modules by Argument Clinic. The _PyArg_Parser.kwtuple field is a tuple object, even though it's stored within a static global. In some cases the tuple is statically allocated and thus it's okay that it gets shared by multiple interpreters. However, in other cases the tuple is set lazily, allocated from the heap using the active interprepreter at the point the tuple is needed.
This is a problem once that interpreter is destroyed since _PyArg_Parser.kwtuple becomes at dangling pointer, leading to crashes. It isn't a problem if the tuple is allocated under the main interpreter, since its lifetime is bound to the lifetime of the runtime. The solution here is to temporarily switch to the main interpreter. The alternative would be to always statically allocate the tuple.
This change also fixes a bug where only the most recent parser was added to the global linked list.
The PEP 649 implementation will require a way to load NotImplementedError
from the bytecode. @markshannon suggested implementing this by converting
LOAD_ASSERTION_ERROR into a more general mechanism for loading constants.
This PR adds this new opcode. I will work on the rest of the implementation
of the PEP separately.
Co-authored-by: Irit Katriel <1055913+iritkatriel@users.noreply.github.com>
Mark Shannon
Donghee Na
Irit Katriel
Brandt Bucher
Pablo Galindo Salgado
Sam Gross
Eric Snow
Tian Gao
Serhiy Storchaka
sobolevn
Victor Stinner
neonene
Jelle Zijlstra
jianghuyiyuan
Michael Droettboom
Petr Viktorin
Sergey B Kirpichev
mpage
Ken Jin
Lysandros Nikolaou
Hood Chatham
Gregor
Josh Brobst
Bénédikt Tran
Kirill Podoprigora
Nadeshiko Manju
Steve Dower
Peter
Xie Yanbo
devdanzin
Daniele Parmeggiani
AN Long
Carson Radtke
Adam Williamson
ixgbe00
Carl Meyer
Saul Shanabrook
Alyssa Coghlan
scoder
Brett Simmers
Jeremy Hylton