Changing the title to "compileall fails when the platform lacks a functional  sem_open()" as the problem lies in the compileall module itself.
Nosying Antoine as the author of issue #36786.


compileall fails on android API 24:

generic_x86_64:/data/local/tmp/python $ python -m compileall --workers=2 .
Traceback (most recent call last):
  File "/data/local/tmp/python/lib/python3.9/multiprocessing/synchronize.py", line 28, in <module>
    from _multiprocessing import SemLock, sem_unlink
ImportError: cannot import name 'SemLock' from '_multiprocessing' (/data/local/tmp/python/lib/python3.9/lib-dynload/_multiprocessing.cpython-39d.so)

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/data/local/tmp/python/lib/python3.9/runpy.py", line 192, in _run_module_as_main
    return _run_code(code, main_globals, None,
  File "/data/local/tmp/python/lib/python3.9/runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "/data/local/tmp/python/lib/python3.9/compileall.py", line 425, in <module>
    exit_status = int(not main())
  File "/data/local/tmp/python/lib/python3.9/compileall.py", line 403, in main
    if not compile_dir(dest, maxlevels, args.ddir,
  File "/data/local/tmp/python/lib/python3.9/compileall.py", line 91, in compile_dir
    with ProcessPoolExecutor(max_workers=workers) as executor:
  File "/data/local/tmp/python/lib/python3.9/concurrent/futures/process.py", line 555, in __init__
    self._call_queue = _SafeQueue(
  File "/data/local/tmp/python/lib/python3.9/concurrent/futures/process.py", line 165, in __init__
    super().__init__(max_size, ctx=ctx)
  File "/data/local/tmp/python/lib/python3.9/multiprocessing/queues.py", line 42, in __init__
    self._rlock = ctx.Lock()
  File "/data/local/tmp/python/lib/python3.9/multiprocessing/context.py", line 67, in Lock
    from .synchronize import Lock
  File "/data/local/tmp/python/lib/python3.9/multiprocessing/synchronize.py", line 30, in <module>
    raise ImportError("This platform lacks a functioning sem_open" +
ImportError: This platform lacks a functioning sem_open implementation, therefore, the required synchronization primitives needed will not function, see issue 3770.