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File-based locks for Python for Linux and Windows

Project Description

Locket implements a lock that can be used by multiple processes provided they use the same path.

import locket

# Wait for lock
with locket.lock_file("path/to/lock/file"):

# Raise error if lock cannot be acquired immediately
with locket.lock_file("path/to/lock/file", timeout=0):

# Raise error if lock cannot be acquired after thirty seconds
with locket.lock_file("path/to/lock/file", timeout=30):

# Without context managers:
lock = locket.lock_file("path/to/lock/file")

Locks largely behave as (non-reentrant) Lock instances from the threading module in the standard library. Specifically, their behaviour is:

  • Locks are uniquely identified by the file being locked, both in the same process and across different processes.
  • Locks are either in a locked or unlocked state.
  • When the lock is unlocked, calling acquire() returns immediately and changes the lock state to locked.
  • When the lock is locked, calling acquire() will block until the lock state changes to unlocked, or until the timeout expires.
  • If a process holds a lock, any thread in that process can call release() to change the state to unlocked.
  • Behaviour of locks after fork is undefined.

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Source May 19, 2015

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