Cross-platform Python locking

Coordinate access. Keep your code simple.

File locks for Python on Linux, macOS and Windows. Use a context manager to coordinate access between processes, or Redis locks across machines.

Get started → Choose a lock

Start with a file lock

Install portalocker on Python 3.10 or later:

python -m pip install portalocker

Use the file handle inside the context:

import portalocker

with portalocker.Lock('report.txt', 'a', timeout=5) as fh:
    fh.write('Report complete.\n')

Lock waits up to five seconds to acquire the file lock. Leaving the context releases the lock and closes the file, including when the body raises an exception. Give every participating process the same file path.

Choose the lock for your task

File locks

Coordinate readers and writers on a shared filesystem.

File locking guide →

Redis locks

Coordinate processes across machines using Redis pub/sub.

Redis guide →

Workers and slots

Run one worker with a PID file, or limit concurrency with a semaphore.

Lock types →

Note

Unix file locks are advisory, so every participating process must lock. Shared file locks on Windows require the optional win32 extra. Check Platform Behaviour for filesystem behaviour and network storage caveats.