From 13752743bf7010f7cbf07bdf2a0087c3960121c5 Mon Sep 17 00:00:00 2001
From: Andrew Dunstan <andrew@dunslane.net>
Date: Wed, 1 Feb 2017 17:52:35 -0500
Subject: Don't count background workers against a user's connection limit.

Doing so doesn't seem to be within the purpose of the per user
connection limits, and has particularly unfortunate effects in
conjunction with parallel queries.

Backpatch to 9.6 where parallel queries were introduced.

David Rowley, reviewed by Robert Haas and Albe Laurenz.
---
 src/backend/storage/ipc/procarray.c | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

(limited to 'src/backend/storage/ipc')

diff --git a/src/backend/storage/ipc/procarray.c b/src/backend/storage/ipc/procarray.c
index 4adb286d5b5..651c561dfd5 100644
--- a/src/backend/storage/ipc/procarray.c
+++ b/src/backend/storage/ipc/procarray.c
@@ -2751,6 +2751,38 @@ CountDBBackends(Oid databaseid)
 	return count;
 }
 
+/*
+ * CountDBConnections --- counts database backends ignoring any background
+ *		worker processes
+ */
+int
+CountDBConnections(Oid databaseid)
+{
+	ProcArrayStruct *arrayP = procArray;
+	int			count = 0;
+	int			index;
+
+	LWLockAcquire(ProcArrayLock, LW_SHARED);
+
+	for (index = 0; index < arrayP->numProcs; index++)
+	{
+		int			pgprocno = arrayP->pgprocnos[index];
+		volatile PGPROC *proc = &allProcs[pgprocno];
+
+		if (proc->pid == 0)
+			continue;			/* do not count prepared xacts */
+		if (proc->isBackgroundWorker)
+			continue;			/* do not count background workers */
+		if (!OidIsValid(databaseid) ||
+			proc->databaseId == databaseid)
+			count++;
+	}
+
+	LWLockRelease(ProcArrayLock);
+
+	return count;
+}
+
 /*
  * CancelDBBackends --- cancel backends that are using specified database
  */
@@ -2810,6 +2842,8 @@ CountUserBackends(Oid roleid)
 
 		if (proc->pid == 0)
 			continue;			/* do not count prepared xacts */
+		if (proc->isBackgroundWorker)
+			continue;			/* do not count background workers */
 		if (proc->roleId == roleid)
 			count++;
 	}
-- 
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