Simon Willison’s Weblog

Thread Synchronization Mechanisms in Python. Locks, RLocks, Semaphores, Events and Conditions as explained by Fredrik Lundh.

Posted 29th July 2007 at 9:32 pm

Recent articles

Fly's new Sprites.dev addresses both developer sandboxes and API sandboxes at the same time - 9th January 2026
LLM predictions for 2026, shared with Oxide and Friends - 8th January 2026
Introducing gisthost.github.io - 1st January 2026

conditions 1 effbot 4 events 108 fredrik-lundh 7 locks 1 python 1220 rlocks 1 semaphores 1 threads 18 tutorial 18

Monthly briefing

Sponsor me for $10/month and get a curated email digest of the month's most important LLM developments.

Pay me to send you less!

Sponsor & subscribe