On 4/11/07, Tom Lane <[EMAIL PROTECTED]> wrote:
[ itch... ] The problem is with time-extended execution of GetSnapshotData; what happens if the other guy lost the CPU for a good long time while in the middle of GetSnapshotData? He might set his xmin based on info you saw as long gone. You might be correct that it's safe, but the argument would have to hinge on the OldestXmin process being unable to commit because of someone holding shared ProcArrayLock; a point you are definitely not making above. (Study the comments in GetSnapshotData for awhile, also those in xact.c's commit-related code.)
My argument was based on what you said above, but I obviously did not state it well :) Anyways, I think its better to be safe and we agree that its not such a bad thing to take exclusive lock on procarray because CIC is not something that happens very often. Attached is a revised patch which takes exclusive lock on the procarray, rest remaining the same. Thanks, Pavan -- EnterpriseDB http://www.enterprisedb.com
CIC_deadlock_v2.patch
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