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Commit3793310

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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 nonewlines. 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 portabilityrisks. I am also thinking of increasing PG_SYSLOG_LIMIT, but that shouldbe done separately.
1 parentcac2f69 commit3793310

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1 file changed

+7
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‎src/backend/utils/error/elog.c

Lines changed: 7 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -42,7 +42,7 @@
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*
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*
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* IDENTIFICATION
45-
* $PostgreSQL: pgsql/src/backend/utils/error/elog.c,v 1.203 2008/03/24 18:08:47 tgl Exp $
45+
* $PostgreSQL: pgsql/src/backend/utils/error/elog.c,v 1.204 2008/07/08 22:17:41 tgl Exp $
4646
*
4747
*-------------------------------------------------------------------------
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*/
@@ -1306,6 +1306,7 @@ write_syslog(int level, const char *line)
13061306
staticunsigned longseq=0;
13071307

13081308
intlen;
1309+
constchar*nlpos;
13091310

13101311
/* Open syslog connection if not done yet */
13111312
if (!openlog_done)
@@ -1328,17 +1329,17 @@ write_syslog(int level, const char *line)
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* fact, it does work around by splitting up messages into smaller pieces.
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*
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* We divide into multiple syslog() calls if message is too long or if the
1331-
* message contains embeddedNewLine(s) '\n'.
1332+
* message contains embeddednewline(s).
13321333
*/
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len=strlen(line);
1334-
if (len>PG_SYSLOG_LIMIT||strchr(line,'\n')!=NULL)
1335+
nlpos=strchr(line,'\n');
1336+
if (len>PG_SYSLOG_LIMIT||nlpos!=NULL)
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{
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intchunk_nr=0;
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while (len>0)
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{
13401342
charbuf[PG_SYSLOG_LIMIT+1];
1341-
constchar*nlpos;
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intbuflen;
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inti;
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@@ -1347,11 +1348,12 @@ write_syslog(int level, const char *line)
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{
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line++;
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len--;
1351+
/* we need to recompute the next newline's position, too */
1352+
nlpos=strchr(line,'\n');
13501353
continue;
13511354
}
13521355

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/* copy one line, or as much as will fit, to buf */
1354-
nlpos=strchr(line,'\n');
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if (nlpos!=NULL)
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buflen=nlpos-line;
13571359
else

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