From 32ac7a118fc17f5baac1b370f50d759c30bee00a Mon Sep 17 00:00:00 2001 From: Simon Riggs Date: Thu, 7 Jun 2018 20:38:12 +0100 Subject: [PATCH] Exclude VACUUMs from RunningXactData GetRunningTransactionData() should ignore VACUUM procs because in some cases they are assigned xids. This could lead to holding back xmin via the route of passing the xid to standby and then having that hold back xmin on master via feedback. Backpatch to 9.1 needed, but will only do so on supported versions. Backpatch once proven on the buildfarm. Reported-by: Greg Stark Author: Simon Riggs Reviewed-by: Amit Kapila Discussion: https://postgr.es/m/CANP8+jJBYt=4PpTfiPb0UrH1_iPhzsxKH5Op_Wec634F0ohnAw@mail.gmail.com --- src/backend/storage/ipc/procarray.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/src/backend/storage/ipc/procarray.c b/src/backend/storage/ipc/procarray.c index afe1c03aa3..9db184f8fe 100644 --- a/src/backend/storage/ipc/procarray.c +++ b/src/backend/storage/ipc/procarray.c @@ -1907,7 +1907,7 @@ ProcArrayInstallRestoredXmin(TransactionId xmin, PGPROC *proc) * GetRunningTransactionData -- returns information about running transactions. * * Similar to GetSnapshotData but returns more information. We include - * all PGXACTs with an assigned TransactionId, even VACUUM processes. + * all PGXACTs with an assigned TransactionId, but not VACUUM processes. * * We acquire XidGenLock and ProcArrayLock, but the caller is responsible for * releasing them. Acquiring XidGenLock ensures that no new XIDs enter the proc @@ -1995,6 +1995,10 @@ GetRunningTransactionData(void) volatile PGXACT *pgxact = &allPgXact[pgprocno]; TransactionId xid; + /* Ignore procs running LAZY VACUUM */ + if (pgxact->vacuumFlags & PROC_IN_VACUUM) + continue; + /* Fetch xid just once - see GetNewTransactionId */ xid = pgxact->xid;