| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Heikki Linnakangas <heikki(at)enterprisedb(dot)com>, "Dorochevsky, Michel" <michel(dot)dorochevsky(at)softcon(dot)de>, pgsql-bugs(at)postgresql(dot)org, Dave Page <dpage(at)postgresql(dot)org> |
| Subject: | Re: BUG #3245: PANIC: failed to re-find shared loc k o b j ect |
| Date: | 2007-04-24 04:37:20 |
| Message-ID: | 23704.1177389440@sss.pgh.pa.us |
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| Lists: | pgsql-bugs pgsql-hackers pgsql-patches |
I wrote:
> Now to start debugging.
It looks to me like the problem is that AtPrepare_Locks invokes
LockTagIsTemp, and that goes and reads various system catalogs, which
can result in new entries in the LOCALLOCK hash table, which might
result in a bucket split in same, which would result in some entries
possibly being scanned twice by the hash_seq_search scan.
Not sure about good fix, except that AtPrepare is probably a really
bad time to be doing fresh catalog searches.
Also, we have a generic issue that making fresh entries in a hashtable
might result in a concurrent hash_seq_search scan visiting existing
entries more than once; that's definitely not something any of the
existing callers are thinking about.
I'm too tired to think about fixes right now, but we've definitely
found a hotbed of actual and potential bugs.
regards, tom lane
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