Don't report stats in LogicalRepApplyLoop() when in xact.

anarazel · anarazel · commit 0cf16cb8ca48 · 2022-05-12T18:54:26.000-07:00
pgstat_report_stat() is only supposed to be called outside of transactions. In 5891c7a I added a pgstat_report_stat() call into LogicalRepApplyLoop()'s timeout branch. While not commonly reached inside a transaction, it is reachable (e.g. due to network bottlenecks or the sender being stalled / slow for some reason). To fix, add a !IsTransactionState() check. No test added because there's no easy way to reproduce this case without patching the code. Reported-By: Erik Rijkers <er@xs4all.nl> Discussion: https://postgr.es/m/b3463b8c-2328-dcac-0136-af95715493c1@xs4all.nl
diff --git a/src/backend/replication/logical/worker.c b/src/backend/replication/logical/worker.c
@@ -2883,9 +2883,14 @@ LogicalRepApplyLoop(XLogRecPtr last_received)
 
 			/*
 			 * Force reporting to ensure long idle periods don't lead to
-			 * arbitrarily delayed stats.
+			 * arbitrarily delayed stats. Stats can only be reported outside
+			 * of (implicit or explicit) transactions. That shouldn't lead to
+			 * stats being delayed for long, because transactions are either
+			 * sent as a whole on commit or streamed. Streamed transactions
+			 * are spilled to disk and applied on commit.
 			 */
-			pgstat_report_stat(true);
+			if (!IsTransactionState())
+				pgstat_report_stat(true);
 		}
 	}
 
