On Tue, 2011-03-01 at 10:02 -0500, Tom Lane wrote: > Simon Riggs <si...@2ndquadrant.com> writes: > > On Tue, 2011-03-01 at 15:51 +0900, Fujii Masao wrote: > >> A spinlock can be used only for very short-term operation like > >> read/write of some shared-variables. The operation on the queue > >> is not short, so should be protected by LWLock, I think. > > > There's no need to sleep while holding locks and the operations are very > > short in most cases. The code around it isn't trivial, but that's no > > reason to use LWlocks. > > What does "in most cases" mean? > > > LWlocks are just spinlocks plus sem sleeps, so I don't see the need for > > that in the current code. Other views welcome. > > Simon, that is absolutely NOT acceptable. Spinlocks are to be used only > for short straight-line code segments. If the lock has any potential to > be held for more than nanoseconds, use an LWLock. The contention costs > of the shortcut you propose are too high.
No problem to change. -- Simon Riggs http://www.2ndQuadrant.com/books/ PostgreSQL Development, 24x7 Support, Training and Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
