The `PyEval_SetProfileAllThreads` function and other related functions
had a race condition on `tstate->c_profilefunc` that could lead to a
crash when disable profiling or tracing on all threads while another
thread is starting to profile or trace a a call.
There are still potential crashes when threads exit concurrently with
profiling or tracing be enabled/disabled across all threads.
(cherry picked from commit 362692852f)
gh-124402: Speed up test_free_threading and test_super (#124491)
* Reduce the number of iterations and the number of threads so a
whole test file takes less than a minute.
* Refactor test_racing_iter_extend() to remove two levels of
indentation.
* test_monitoring() uses a sleep of 100 ms instead of 1 second.
(cherry picked from commit 0387c34f7c)
gh-124402: Require cpu resource in test_free_threading (#124438)
Require the 'cpu' test resource on slow test_free_threading tests.
(cherry picked from commit 38a5beb12a)
Makes sys.settrace, sys.setprofile, and monitoring generally thread-safe.
Mostly uses a stop-the-world approach and synchronization around the code object's _co_instrumentation_version. There may be a little bit of extra synchronization around the monitoring data that's required to be TSAN clean.
