Python threading 模块，_PyRLock() 实例源码

def _green_existing_locks():
    """Make locks created before monkey-patching safe.

    RLocks rely on a Lock and on Python 2, if an unpatched Lock blocks, it
    blocks the native thread. We need to replace these with green Locks.

    This was originally noticed in the stdlib logging module."""
    import gc
    import threading
    import eventlet.green.thread
    lock_type = type(threading.Lock())
    rlock_type = type(threading.RLock())
    if sys.version_info[0] >= 3:
        pyrlock_type = type(threading._PyRLock())
    # We're monkey-patching so there can't be any greenlets yet, ergo our thread
    # ID is the only valid owner possible.
    tid = eventlet.green.thread.get_ident()
    for obj in gc.get_objects():
        if isinstance(obj, rlock_type):
            if (sys.version_info[0] == 2 and
                    isinstance(obj._RLock__block, lock_type)):
                _fix_py2_rlock(obj, tid)
            elif (sys.version_info[0] >= 3 and
                    not isinstance(obj, pyrlock_type)):
                _fix_py3_rlock(obj)

def _green_existing_locks():
    """Make locks created before monkey-patching safe.

    RLocks rely on a Lock and on Python 2, if an unpatched Lock blocks, it
    blocks the native thread. We need to replace these with green Locks.

    This was originally noticed in the stdlib logging module."""
    import gc
    import threading
    import eventlet.green.thread
    lock_type = type(threading.Lock())
    rlock_type = type(threading.RLock())
    if sys.version_info[0] >= 3:
        pyrlock_type = type(threading._PyRLock())
    # We're monkey-patching so there can't be any greenlets yet, ergo our thread
    # ID is the only valid owner possible.
    tid = eventlet.green.thread.get_ident()
    for obj in gc.get_objects():
        if isinstance(obj, rlock_type):
            if (sys.version_info[0] == 2 and
                    isinstance(obj._RLock__block, lock_type)):
                _fix_py2_rlock(obj, tid)
            elif (sys.version_info[0] >= 3 and
                    not isinstance(obj, pyrlock_type)):
                _fix_py3_rlock(obj)

def _fix_py3_rlock(old):
    import gc
    import threading
    new = threading._PyRLock()
    while old._is_owned():
        old.release()
        new.acquire()
    if old._is_owned():
        new.acquire()
    gc.collect()
    for ref in gc.get_referrers(old):
        try:
            ref_vars = vars(ref)
        except TypeError:
            pass
        else:
            for k, v in ref_vars.items():
                if v == old:
                    setattr(ref, k, new)

def _fix_py3_rlock(old):
    import gc
    import threading
    new = threading._PyRLock()
    while old._is_owned():
        old.release()
        new.acquire()
    if old._is_owned():
        new.acquire()
    gc.collect()
    for ref in gc.get_referrers(old):
        for k, v in vars(ref):
            if v == old:
                setattr(ref, k, new)