From 90857b48e1f69dbca52f498bd444190d36dbd73f Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Fri, 27 May 2011 12:10:32 -0400
Subject: [PATCH] Preserve caller's memory context in
ProcessCompletedNotifies().
This is necessary to avoid long-term memory leakage, because the main loop
in PostgresMain expects to be executing in MessageContext, and hence is a
bit sloppy about freeing stuff that is only needed for the duration of
processing the current client message. The known case of an actual leak
is when encoding conversion has to be done on the incoming command string,
but there might be others. Per report from Per-Olov Esgard.
Back-patch to 9.0, where the bug was introduced by the LISTEN/NOTIFY
rewrite.
---
src/backend/commands/async.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/src/backend/commands/async.c b/src/backend/commands/async.c
index 588e9f2b85..02f8f9cd63 100644
--- a/src/backend/commands/async.c
+++ b/src/backend/commands/async.c
@@ -1090,6 +1090,7 @@ Exec_UnlistenAllCommit(void)
void
ProcessCompletedNotifies(void)
{
+ MemoryContext caller_context;
bool signalled;
/* Nothing to do if we didn't send any notifications */
@@ -1103,6 +1104,12 @@ ProcessCompletedNotifies(void)
*/
backendHasSentNotifications = false;
+ /*
+ * We must preserve the caller's memory context (probably MessageContext)
+ * across the transaction we do here.
+ */
+ caller_context = CurrentMemoryContext;
+
if (Trace_notify)
elog(DEBUG1, "ProcessCompletedNotifies");
@@ -1135,6 +1142,8 @@ ProcessCompletedNotifies(void)
CommitTransactionCommand();
+ MemoryContextSwitchTo(caller_context);
+
/* We don't need pq_flush() here since postgres.c will do one shortly */
}