From d32400881e181f360e064b5f0ed0119c3006002e Mon Sep 17 00:00:00 2001 From: Bertrand Drouvot Date: Fri, 8 Aug 2025 15:58:05 +0000 Subject: [PATCH v4 2/3] Adding XID generation count per backend This commit adds a new counter to record the number of XIDs generated per backend. It will help to detect if a backend is consuming XIDs at a high rate. Virtual transactions are not taken into account on purpose, we do want to track only the XID where there is a risk of wraparound. --- src/backend/access/transam/varsup.c | 4 ++++ src/backend/utils/activity/pgstat_backend.c | 2 ++ src/include/pgstat.h | 2 ++ 3 files changed, 8 insertions(+) 43.8% src/backend/access/transam/ 36.6% src/backend/utils/activity/ 19.4% src/include/ diff --git a/src/backend/access/transam/varsup.c b/src/backend/access/transam/varsup.c index f8c4dada7c9..72c8aa7650b 100644 --- a/src/backend/access/transam/varsup.c +++ b/src/backend/access/transam/varsup.c @@ -24,6 +24,7 @@ #include "storage/pmsignal.h" #include "storage/proc.h" #include "utils/lsyscache.h" +#include "utils/pgstat_internal.h" #include "utils/syscache.h" @@ -257,6 +258,9 @@ GetNewTransactionId(bool isSubXact) /* LWLockRelease acts as barrier */ MyProc->xid = xid; ProcGlobal->xids[MyProc->pgxactoff] = xid; + PendingBackendStats.pending_xid_count++; + backend_has_xactstats = true; + pgstat_report_fixed = true; } else { diff --git a/src/backend/utils/activity/pgstat_backend.c b/src/backend/utils/activity/pgstat_backend.c index 47ce61e5093..5e509153656 100644 --- a/src/backend/utils/activity/pgstat_backend.c +++ b/src/backend/utils/activity/pgstat_backend.c @@ -285,9 +285,11 @@ pgstat_flush_backend_entry_xact(PgStat_EntryRef *entry_ref) shbackendent->stats.xact_commit += PendingBackendStats.pending_xact_commit; shbackendent->stats.xact_rollback += PendingBackendStats.pending_xact_rollback; + shbackendent->stats.xid_count += PendingBackendStats.pending_xid_count; PendingBackendStats.pending_xact_commit = 0; PendingBackendStats.pending_xact_rollback = 0; + PendingBackendStats.pending_xid_count = 0; backend_has_xactstats = false; } diff --git a/src/include/pgstat.h b/src/include/pgstat.h index 0fdbaf79780..d78633cae44 100644 --- a/src/include/pgstat.h +++ b/src/include/pgstat.h @@ -492,6 +492,7 @@ typedef struct PgStat_Backend PgStat_WalCounters wal_counters; PgStat_Counter xact_commit; PgStat_Counter xact_rollback; + PgStat_Counter xid_count; } PgStat_Backend; /* --------- @@ -510,6 +511,7 @@ typedef struct PgStat_BackendPending */ PgStat_Counter pending_xact_commit; PgStat_Counter pending_xact_rollback; + PgStat_Counter pending_xid_count; } PgStat_BackendPending; /* -- 2.34.1