The RP2040 has 2 cores and supports running at most 2 Python threads (the
main one plus another), and will raise OSError if a thread cannot be
created because core1 is already in use. This commit adjusts some thread
tests to be robust against such OSError's. These tests now pass on rp2
boards.
Signed-off-by: Damien George <damien@micropython.org>
This commit makes gc_lock_depth have one counter per thread, instead of one
global counter. This makes threads properly independent with respect to
the GC, in particular threads can now independently lock the GC for
themselves without locking it for other threads. It also means a given
thread can run a hard IRQ without temporarily locking the GC for all other
threads and potentially making them have MemoryError exceptions at random
locations (this really only occurs on MCUs with multiple cores and no GIL,
eg on the rp2 port).
The commit also removes protection of the GC lock/unlock functions, which
is no longer needed when the counter is per thread (and this also fixes the
cas where a hard IRQ calling gc_lock() may stall waiting for the mutex).
It also puts the check for `gc_lock_depth > 0` outside the GC mutex in
gc_alloc, gc_realloc and gc_free, to potentially prevent a hard IRQ from
waiting on a mutex if it does attempt to allocate heap memory (and putting
the check outside the GC mutex is now safe now that there is a
gc_lock_depth per thread).
Signed-off-by: Damien George <damien@micropython.org>
So a lock can be acquired on one Python thread and then released on
another. A test for this is added.
Signed-off-by: Damien George <damien@micropython.org>
When threading is enabled without the GIL then there can be races between
the threads accessing the globals dict. Avoid this issue by making sure
all globals variables are allocated before starting the threads.
Signed-off-by: Damien George <damien@micropython.org>
This is consistent with the other 'micro' modules and allows implementing
additional features in Python via e.g. micropython-lib's sys.
Note this is a breaking change (not backwards compatible) for ports which
do not enable weak links, as "import sys" must now be replaced with
"import usys".
On arm64 with CPython:
>>> _thread.stack_size(32*1024)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
ValueError: size not valid: 32768 bytes
So increase the CPython value in the test to 512k so it runs on more
systems (on modern Linux the default stack size is usually 8MB).
This adds the Python files in the tests/ directory to be formatted with
./tools/codeformat.py. The basics/ subdirectory is excluded for now so we
aren't changing too much at once.
In a few places `# fmt: off`/`# fmt: on` was used where the code had
special formatting for readability or where the test was actually testing
the specific formatting.
Depending on the thread scheduler, a busy-wait loop can hog the CPU and
make the tests very slow. So convert such loops to loops that have an
explicit sleep, allowing the worker threads to do their job.
Damien George