>On Wed, 2009-12-16 at 19:35 +0900, Hiroyuki Yamada wrote: > >> * There is a window beween gathering lock information in >> GetRunningTransactionLocks() >> and writing WAL in LogAccessExclusiveLocks(). >> * In current lock redo algorithm, locks are released when the transaction >> holding the lock >> are commited or aborted. >> >> ... then what happens if any transaction holding ACCESS EXCLUSIVE lock >> commits in the >> window ? > >Yes, was a problem in that code. Fixed in git. > >We were doing it for prepared transactions but not for normal xacts. >I will look again at that code. > >Thanks very much for reading the code. Any more?!? >
Well, I've read some more and have a question. The implementation assumes that transactions write COMMIT/ABORT WAL at the end of them, while it does not seem to write ABORT WAL in immediate shutdown. So, 1. acquire ACCESS EXCLUSIVE lock in table A in xact 1 2. execute immediate shutdown of the active node 3. restart it 4. acquire ACCESS EXCLUSIVE lock in table A in xact 2 ...then, duplicate lock acquisition by two diffrent transactions can occur in the standby node. Am I missing something ? Or is this already reported ? regards, -- Hiroyuki YAMADA Kokolink Corporation yam...@kokolink.net -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
