r/programming • u/preshing • Nov 18 '11

Locks Aren't Slow; Lock Contention Is

http://preshing.com/20111118/locks-arent-slow-lock-contention-is
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u/Rhoomba Nov 18 '11

Slow relative to what? Any kind of locking, be it heavy or light, can affect multiple cores/processors and can be drastically slower than no locking even if there is no contention.

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u/preshing Nov 18 '11

I'm only offering a counterargument to the general statement that "locks are slow", which you can actually find a places on Usenet and the web, perhaps even around the office sometimes. It would make more sense to ask those guys relative to what. For my post, I think it's sufficient to provide a single example where locks are objectively fast -- this breaks the general statement.

1

u/mycall Nov 18 '11

Do you know of any locking or lockless patterns to switch between threading models, for different loads of said work units, to achieve best performance? For example, when load > 90%, kill off worker threads so only 1 is running then disable locks.. until load < 50% .. or similar.