python lock with-statement and timeout

python-3.x locking with-statement
Tsf picture Tsf · May 24, 2013 · Viewed 7.6k times · Source

I am using a Python 3 sequence like this:

lock = threading.Lock()
res = lock.acquire(timeout=10)
if res:
    # do something ....
    lock.release()
else:
    # do something else ...

I would prefer to use a with-statement instead of explicit "acquire" and "release", but I don't know how to get the timeout effect.

Answer

robbles picture robbles · May 28, 2013

You can do this pretty easily with a context manager:

import threading
from contextlib import contextmanager

@contextmanager
def acquire_timeout(lock, timeout):
    result = lock.acquire(timeout=timeout)
    yield result
    if result:
        lock.release()


# Usage:
lock = threading.Lock()

with acquire_timeout(lock, 2) as acquired:
    if acquired:
        print('got the lock')
        # do something ....
    else:
        print('timeout: lock not available')
        # do something else ...

*Note: This won't work in Python 2.x since there isn't a timeout argument to Lock.acquire

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