Each thread specializes a thread-local copy of the bytecode, created on the first RESUME, in free-threaded builds. All copies of the bytecode for a code object are stored in the co_tlbc array on the code object. Threads reserve a globally unique index identifying its copy of the bytecode in all co_tlbc arrays at thread creation and release the index at thread destruction. The first entry in every co_tlbc array always points to the "main" copy of the bytecode that is stored at the end of the code object. This ensures that no bytecode is copied for programs that do not use threads.
Thread-local bytecode can be disabled at runtime by providing either -X tlbc=0 or PYTHON_TLBC=0. Disabling thread-local bytecode also disables specialization.
Concurrent modifications to the bytecode made by the specializing interpreter and instrumentation use atomics, with specialization taking care not to overwrite an instruction that was instrumented concurrently.
* Remove `@suppress_immortalization` decorator
* Make suppression flag per-thread instead of per-interpreter
* Suppress immortalization in `eval()` to avoid refleaks in three tests
(test_datetime.test_roundtrip, test_logging.test_config8_ok, and
test_random.test_after_fork).
* frozenset() is constant, but not a singleton. When run multiple times,
the test could fail due to constant interning.
Run them with different locales and different date and time.
Add the @run_with_locales() decorator to run the test with multiple
locales.
Improve the run_with_locale() context manager/decorator -- it now
catches only expected exceptions and reports the test as skipped if no
appropriate locale is available.
Fix the incorrect use of `os.open()` result as a context manager,
while it is actually a numeric file descriptor.
I have missed the problem, because in the original version the
`os.open()` call would always fail, and I failed to test the final
version in all possible scenarios properly.
Change the default multiprocessing start method away from fork to forkserver or spawn on the remaining platforms where it was fork. See the issue for context. This makes the default far more thread safe (other than for people spawning threads at import time... - don't do that!).
Co-authored-by: blurb-it[bot] <43283697+blurb-it[bot]@users.noreply.github.com>
Co-authored-by: Hugo van Kemenade <1324225+hugovk@users.noreply.github.com>
* Detect source file encoding.
* Use the "replace" error handler even for UTF-8 (default) encoding.
* Remove the BOM.
* Fix detection of too long lines if they contain NUL.
* Return the head rather than the tail for truncated long lines.
Add a helper function that checks whether the test suite is running
inside a systemd-nspawn container, and skip the few tests failing
with `--suppress-sync=true` in that case. The tests are failing because
`--suppress-sync=true` stubs out `fsync()`, `fdatasync()` and `msync()`
calls, and therefore they always return success without checking for
invalid arguments.
Call `os.open(__file__, os.O_RDONLY | os.O_SYNC)` and check the errno to
detect whether `--suppress-sync=true` is actually used, and skip
the tests only in that scenario.
There were a still a number of gaps in the tests, including not looking
at all the builtin types and not checking wrappers in subinterpreters
that weren't in the main interpreter. This fixes all that.
I considered incorporating the names of the PyTypeObject fields
(a la gh-122866), but figured doing so doesn't add much value.
The tests were only checking cases where the slot wrapper was present in the initial case. They were missing when the slot wrapper was added in the additional initializations. This fixes that.
Any cross-interpreter mechanism for passing objects between interpreters must be very careful to respect isolation, even when the object is effectively immutable (e.g. int, str). Here this especially relates to when an interpreter sends one of its objects, and then is destroyed while the inter-interpreter machinery (e.g. queue) still holds a reference to the object.
When I added interpreters.Queue, I dealt with that case (using an atexit hook) by silently removing all items from the queue that were added by the finalizing interpreter.
Later, while working on concurrent.futures.InterpreterPoolExecutor (gh-116430), I noticed it was somewhat surprising when items were silently removed from the queue when the originating interpreter was destroyed. (See my comment on that PR.)
It took me a little while to realize what was going on. I expect that users, which much less context than I have, would experience the same pain.
My approach, here, to improving the situation is to give users three options:
1. return a singleton (interpreters.queues.UNBOUND) from Queue.get() in place of each removed item
2. raise an exception (interpreters.queues.ItemInterpreterDestroyed) from Queue.get() in place of each removed item
3. existing behavior: silently remove each item (i.e. Queue.get() skips each one)
The default will now be (1), but users can still explicitly opt in any of them, including to the silent removal behavior.
The behavior for each item may be set with the corresponding Queue.put() call. and a queue-wide default may be set when the queue is created. (This is the same as I did for "synconly".)
* Move get_signal_name() from test.libregrtest to test.support.
* Use get_signal_name() in support.script_helper.
* support.script_helper now decodes stdout and stderr from UTF-8,
instead of ASCII, if a command failed.
The tests were accidentally disabled by 2da0dc0, which didn't handle classes correctly.
I considered updating no_rerun() to support classes, but the way test_datetime.py works would have made things fairly messy. Plus, it looks like the refleaks we had encountered before have been resolved.
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.
As reported in #117847 and #115366, an unpaired backtick in a docstring
tends to confuse e.g. Sphinx running on subclasses of standard library
objects, and the typographic style of using a backtick as an opening
quote is no longer in favor. Convert almost all uses of the form
The variable `foo' should do xyz
to
The variable 'foo' should do xyz
and also fix up miscellaneous other unpaired backticks (extraneous /
missing characters).
No functional change is intended here other than in human-readable
docstrings.
We already intern and immortalize most string constants. In the
free-threaded build, other constants can be a source of reference count
contention because they are shared by all threads running the same code
objects.
The code for Tier 2 is now only compiled when configured
with `--enable-experimental-jit[=yes|interpreter]`.
We drop support for `PYTHON_UOPS` and -`Xuops`,
but you can disable the interpreter or JIT
at runtime by setting `PYTHON_JIT=0`.
You can also build it without enabling it by default
using `--enable-experimental-jit=yes-off`;
enable with `PYTHON_JIT=1`.
On Windows, the `build.bat` script supports
`--experimental-jit`, `--experimental-jit-off`,
`--experimental-interpreter`.
In the C code, `_Py_JIT` is defined as before
when the JIT is enabled; the new variable
`_Py_TIER2` is defined when the JIT *or* the
interpreter is enabled. It is actually a bitmask:
1: JIT; 2: default-off; 4: interpreter.
Deferred reference counting is not fully implemented yet. As a temporary
measure, we immortalize objects that would use deferred reference
counting to avoid multi-threaded scaling bottlenecks.
This is only performed in the free-threaded build once the first
non-main thread is started. Additionally, some tests, including refleak
tests, suppress this behavior.
This is similar to the situation with threading._DummyThread. The methods (incl. __del__()) of interpreters.Interpreter objects must be careful with interpreters not created by interpreters.create(). The simplest thing to start with is to disable any method that modifies or runs in the interpreter. As part of this, the runtime keeps track of where an interpreter was created. We also handle interpreter "refcounts" properly.
