Re: LWLockRelease - Mailing list pgsql-hackers

From Tom Lane
Subject Re: LWLockRelease
Date
Msg-id 15729.1107441172@sss.pgh.pa.us
Whole thread Raw
In response to LWLockRelease  ("Simon Riggs" <simon@2ndquadrant.com>)
List pgsql-hackers
"Simon Riggs" <simon@2ndquadrant.com> writes:
> A few thoughts on LWLock data structures...

> In lwlock.c we hold a list of lwlocks held:
> held_lwlocks[MAX_SIMUL_LWLOCKS]
> where
> #define MAX_SIMUL_LWLOCKS    100

> The code for LWLockRelease assumes that the last acquired lock will
> always be the first one to be released, and uses an O(N) loop to search
> for the lock to release.

> Setting MAX_SIMUL_LWLOCKS to this fairly high number doesn't seem to
> match the optimistic use of the O(N) algorithm.

So?  The search only examines the actually-in-use array entries.
        regards, tom lane


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