Notice Deadlock detected and Backend cache invalidation initialization failed

Hello,

We're using postgresql 6.4.2 on red hat linux 6.0, kernel 2.2.10 with dbi
1.09 and DBD-Pg 0.91 for web database connectivity. We are occasionally
experiencing deadlocks that are logged to the apache logs as follows:

NOTICE: Deadlock detected -- See the lock(l) manual page for a possible
cause.
NOTICE: Deadlock detected -- See the lock(l) manual page for a possible
cause.
DBD::Pg::st execute failed: ERROR: WaitOnLock: error on wakeup - Aborting
this transaction
Database handle destroyed without explicit disconnect.
Database handle destroyed without explicit disconnect.

However, on Friday, we experienced a much more sivere problem where
shortly after the Deadlock errors, the following occured:

NOTICE: SIAssignBackendId: discarding tag 2147474428
DBI->connect failed: FATAL 1: Backend cache invalidation initialization
failed
at /home/sitesell/cgi-bin/Database_Interaction//database_func.pl line 727

After this, none of the scripts would execute and generated 500 server
errors. When I tried to restart postgresql, I got the following error:

Starting postgresql service: IpcMemoryCreate: shmget failed (Identifier
removed) key=5432010, size=24588, permission=700
IpcMemoryIdGet: shmget failed (Identifier removed) key=5432010,
size=24588, permission=0
IpcMemoryAttach: shmat failed (Invalid argument) id=-2
FATAL 1: AttachSLockMemory: could not attach segment
postmaster []

My guess is that your shared memory is still allocated to the crashed
backends. I recommend using pgsql/bin/ipcclean to clear out your shared
memory and restart.

As far as the deadlocks, if the lock manual pages doesn't help show the
cause, I recommend upgrading to 6.5, where we have new locking code.

-- 
  Bruce Momjian                        |  http://www.op.net/~candle
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