Locking with Deadlock Avoidance

import threading

from contextlib import contextmanager

_local = threading.local()

@contextmanager

def acquire(*locks):

locks = sorted(locks, key=lambda x: id(x))

acquired = getattr(_local, 'acquired', [])

if acquired and max(id(lock) for lock in acquired) >= id(locks[0]):

raise RuntimeError('Lock Order Voilation')

acquired.extend(locks)

_local.acquired = acquired

try:

for lock in locks:

lock.acquire()

yield

finally:

for lock in reversed(locks):

lock.release()

del acquired[-len(locks):]

#example usuage:

x_lock = threading.Lock()

y_lock = threading.Lock()

def thread_1():

while True:

with acquire(x_lock, y_lock):

print('Thread-1')

def thread_2():

while True:

with acquire(y_lock, x_lock):

print('Thread-2')