The following code is in the ProcSleep at proc.c:1138.
GetBlockingAutoVacuumPgproc() should presumably always return a vacuum
pgproc entry since the deadlock state says it's blocked by autovacuum.
But I'm not really familiar enough with this codepath to know whether
there's not a race condition here where it can sometimes return null.
The following code checks autovac != NULL but the PGXACT initializer
would have seg faulted if it returned NULL if that's possible.
if (deadlock_state == DS_BLOCKED_BY_AUTOVACUUM &&
allow_autovacuum_cancel) { PGPROC *autovac = GetBlockingAutoVacuumPgproc(); PGXACT
*autovac_pgxact =
&ProcGlobal->allPgXact[autovac->pgprocno];
LWLockAcquire(ProcArrayLock, LW_EXCLUSIVE);
/* * Only do it if the worker is not working to protect against Xid * wraparound.
*/ if ((autovac != NULL) && (autovac_pgxact->vacuumFlags & PROC_IS_AUTOVACUUM) &&
!(autovac_pgxact->vacuumFlags & PROC_VACUUM_FOR_WRAPAROUND)) {
--
greg
