Multiprocessing realtime hook to fix spawn mode for frozen processes on POSIX OSes that use the semaphore tracker

rthook_multiprocessing.py

import sys, os, re

import multiprocessing
import multiprocessing.spawn as spawn

# prevent spawn from trying to read __main__ in from the main script
multiprocessing.process.ORIGINAL_DIR = None

def _freeze_support():
    if 'multiprocessing.semaphore_tracker' in sys.argv[-1]:
        m = re.compile('.*main\((\d+)\)$').match(sys.argv[-1])
        fd = int(m.group(1))
        import multiprocessing.semaphore_tracker
        multiprocessing.semaphore_tracker.main(fd)
        sys.exit()

    if spawn.is_forking(sys.argv):
        kwds = {}
        for arg in sys.argv[2:]:
            name, value = arg.split('=')
            if value == 'None':
                kwds[name] = None
            else:
                kwds[name] = int(value)
        spawn.spawn_main(**kwds)
        sys.exit()

multiprocessing.freeze_support = spawn.freeze_support = _freeze_support

# Module multiprocessing is organized differently in Python 3.4+
try:
    # Python 3.4+
    if sys.platform.startswith('win'):
        import multiprocessing.popen_spawn_win32 as forking
    else:
        import multiprocessing.popen_fork as forking
except ImportError:
    import multiprocessing.forking as forking

# First define a modified version of Popen.
class _Popen(forking.Popen):
    def __init__(self, *args, **kw):
        if hasattr(sys, 'frozen'):
            # We have to set original _MEIPASS2 value from sys._MEIPASS
            # to get --onefile mode working.
            os.putenv('_MEIPASS2', sys._MEIPASS)  # @UndefinedVariable
        try:
            super(_Popen, self).__init__(*args, **kw)
        finally:
            if hasattr(sys, 'frozen'):
                # On some platforms (e.g. AIX) 'os.unsetenv()' is not
                # available. In those cases we cannot delete the variable
                # but only set it to the empty string. The bootloader
                # can handle this case.
                if hasattr(os, 'unsetenv'):
                    os.unsetenv('_MEIPASS2')
                else:
                    os.putenv('_MEIPASS2', '')

forking.Popen = _Popen