Re: bug in fast-path locking
Jim Nasby <jim@nasby.net>
From: Jim Nasby <jim@nasby.net>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Boszormenyi Zoltan <zb@cybertec.at>, Cousin Marc <cousinmarc@gmail.com>, Alvaro Herrera <alvherre@commandprompt.com>, Pg Hackers <pgsql-hackers@postgresql.org>, Hans-Juergen Schoenig <hs@cybertec.at>, Ants Aasma <ants@cybertec.at>
Date: 2012-04-09T22:42:06Z
Lists: pgsql-hackers
On 4/9/12 12:32 PM, Robert Haas wrote: > I looked at this more. The above analysis is basically correct, but > the problem goes a bit beyond an error in LockWaitCancel(). We could > also crap out with an error before getting as far as LockWaitCancel() > and have the same problem. I think that a correct statement of the > problem is this: from the time we bump the strong lock count, up until > the time we're done acquiring the lock (or give up on acquiring it), > we need to have an error-cleanup hook in place that will unbump the > strong lock count if we error out. Once we're done updating the > shared and local lock tables, the special handling ceases to be > needed, because any subsequent lock release will go through > LockRelease() or LockReleaseAll(), which will do the appropriate > clenaup. > > The attached patch is an attempt at implementing that; any reviews appreciated. Dumb question... should operations in the various StrongLock functions take place in a critical section? Or is that already ensure outside of these functions? -- Jim C. Nasby, Database Architect jim@nasby.net 512.569.9461 (cell) http://jim.nasby.net