From 53e95eee84e0f8c680ad813091e7226abb24214e Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Mon, 16 Sep 2002 01:24:41 +0000
Subject: [PATCH] Fix for rare race-condition-like failure: if a backend
receives SIGUSR2 (notify/SI-overrun interrupt) while it is in process of
doing proc_exit, it is possible for Async_NotifyHandler() to try to start a
transaction when one is already running. This leads to Asserts() or worse.
I think it may only be possible to occur when frontend synchronization is
lost (ie, the elog(FATAL) in SocketBackend() fires), but that is a standard
occurrence after error during COPY. In any case, I have seen this failure
occur during regression tests, so it is definitely possible.
---
src/backend/commands/async.c | 6 +++++-
src/backend/tcop/postgres.c | 7 +++++--
2 files changed, 10 insertions(+), 3 deletions(-)
diff --git a/src/backend/commands/async.c b/src/backend/commands/async.c
index 1945c751e18..a3c27b8f810 100644
--- a/src/backend/commands/async.c
+++ b/src/backend/commands/async.c
@@ -7,7 +7,7 @@
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/commands/async.c,v 1.90 2002/09/02 02:47:01 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/backend/commands/async.c,v 1.91 2002/09/16 01:24:41 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -593,6 +593,10 @@ Async_NotifyHandler(SIGNAL_ARGS)
* ever turned on.
*/
+ /* Don't joggle the elbow of proc_exit */
+ if (proc_exit_inprogress)
+ return;
+
if (notifyInterruptEnabled)
{
/*
diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
index 01d810088c8..cd5f76512a3 100644
--- a/src/backend/tcop/postgres.c
+++ b/src/backend/tcop/postgres.c
@@ -8,7 +8,7 @@
*
*
* IDENTIFICATION
- * $Header: /cvsroot/pgsql/src/backend/tcop/postgres.c,v 1.291 2002/09/04 20:31:26 momjian Exp $
+ * $Header: /cvsroot/pgsql/src/backend/tcop/postgres.c,v 1.292 2002/09/16 01:24:41 tgl Exp $
*
* NOTES
* this is the "main" module of the postgres backend and
@@ -1071,12 +1071,14 @@ ProcessInterrupts(void)
ProcDiePending = false;
QueryCancelPending = false; /* ProcDie trumps QueryCancel */
ImmediateInterruptOK = false; /* not idle anymore */
+ DisableNotifyInterrupt();
elog(FATAL, "This connection has been terminated by the administrator.");
}
if (QueryCancelPending)
{
QueryCancelPending = false;
ImmediateInterruptOK = false; /* not idle anymore */
+ DisableNotifyInterrupt();
elog(ERROR, "Query was cancelled.");
}
/* If we get here, do nothing (probably, QueryCancelPending was reset) */
@@ -1689,7 +1691,7 @@ PostgresMain(int argc, char *argv[], const char *username)
if (!IsUnderPostmaster)
{
puts("\nPOSTGRES backend interactive interface ");
- puts("$Revision: 1.291 $ $Date: 2002/09/04 20:31:26 $\n");
+ puts("$Revision: 1.292 $ $Date: 2002/09/16 01:24:41 $\n");
}
/*
@@ -1736,6 +1738,7 @@ PostgresMain(int argc, char *argv[], const char *username)
QueryCancelPending = false;
InterruptHoldoffCount = 1;
CritSectionCount = 0; /* should be unnecessary, but... */
+ DisableNotifyInterrupt();
debug_query_string = NULL;
/*
--
GitLab