From 3793310286546f12bfae9632c81bfaee67a913c1 Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Tue, 8 Jul 2008 22:17:41 +0000
Subject: [PATCH] Fix performance bug in write_syslog(): the code to
 preferentially break the log message at newlines cost O(N^2) for very long
 messages with few or no newlines.  For messages in the megabyte range this
 became the dominant cost. Per gripe from Achilleas Mantzios.

Patch all the way back, since this is a safe change with no portability
risks.  I am also thinking of increasing PG_SYSLOG_LIMIT, but that should
be done separately.
---
 src/backend/utils/error/elog.c | 12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

diff --git a/src/backend/utils/error/elog.c b/src/backend/utils/error/elog.c
index d21ca068b0..0d4fd56a22 100644
--- a/src/backend/utils/error/elog.c
+++ b/src/backend/utils/error/elog.c
@@ -42,7 +42,7 @@
  *
  *
  * IDENTIFICATION
- *	  $PostgreSQL: pgsql/src/backend/utils/error/elog.c,v 1.203 2008/03/24 18:08:47 tgl Exp $
+ *	  $PostgreSQL: pgsql/src/backend/utils/error/elog.c,v 1.204 2008/07/08 22:17:41 tgl Exp $
  *
  *-------------------------------------------------------------------------
  */
@@ -1306,6 +1306,7 @@ write_syslog(int level, const char *line)
 	static unsigned long seq = 0;
 
 	int			len;
+	const char *nlpos;
 
 	/* Open syslog connection if not done yet */
 	if (!openlog_done)
@@ -1328,17 +1329,17 @@ write_syslog(int level, const char *line)
 	 * fact, it does work around by splitting up messages into smaller pieces.
 	 *
 	 * We divide into multiple syslog() calls if message is too long or if the
-	 * message contains embedded NewLine(s) '\n'.
+	 * message contains embedded newline(s).
 	 */
 	len = strlen(line);
-	if (len > PG_SYSLOG_LIMIT || strchr(line, '\n') != NULL)
+	nlpos = strchr(line, '\n');
+	if (len > PG_SYSLOG_LIMIT || nlpos != NULL)
 	{
 		int			chunk_nr = 0;
 
 		while (len > 0)
 		{
 			char		buf[PG_SYSLOG_LIMIT + 1];
-			const char *nlpos;
 			int			buflen;
 			int			i;
 
@@ -1347,11 +1348,12 @@ write_syslog(int level, const char *line)
 			{
 				line++;
 				len--;
+				/* we need to recompute the next newline's position, too */
+				nlpos = strchr(line, '\n');
 				continue;
 			}
 
 			/* copy one line, or as much as will fit, to buf */
-			nlpos = strchr(line, '\n');
 			if (nlpos != NULL)
 				buflen = nlpos - line;
 			else