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Commit3ad0728

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On systems that have setsid(2) (which should be just about everything except
Windows), arrange for each postmaster child process to be its own processgroup leader, and deliver signals SIGINT, SIGTERM, SIGQUIT to the wholeprocess group not only the direct child process. This provides saner behaviorfor archive and recovery scripts; in particular, it's possible to shut down awarm-standby recovery server using "pg_ctl stop -m immediate", since deliveryof SIGQUIT to the startup subprocess will result in killing the waitingrecovery_command. Also, this makes Query Cancel and statement_timeout applyto scripts being run from backends via system(). (There is no support in thecore backend for that, but it's widely done using untrusted PLs.) Per gripefrom Stephen Harris and subsequent discussion.
1 parentde59715 commit3ad0728

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11 files changed

+204
-48
lines changed

11 files changed

+204
-48
lines changed

‎src/backend/access/transam/xlog.c

Lines changed: 21 additions & 4 deletions
Original file line numberDiff line numberDiff line change
@@ -7,7 +7,7 @@
77
* Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group
88
* Portions Copyright (c) 1994, Regents of the University of California
99
*
10-
* $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.256 2006/11/16 14:28:41 petere Exp $
10+
* $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.257 2006/11/21 20:59:52 tgl Exp $
1111
*
1212
*-------------------------------------------------------------------------
1313
*/
@@ -18,9 +18,10 @@
1818
#include<fcntl.h>
1919
#include<signal.h>
2020
#include<time.h>
21-
#include<unistd.h>
2221
#include<sys/stat.h>
2322
#include<sys/time.h>
23+
#include<sys/wait.h>
24+
#include<unistd.h>
2425

2526
#include"access/clog.h"
2627
#include"access/heapam.h"
@@ -2373,6 +2374,7 @@ RestoreArchivedFile(char *path, const char *xlogfname,
23732374
char*endp;
23742375
constchar*sp;
23752376
intrc;
2377+
boolsignaled;
23762378
structstatstat_buf;
23772379

23782380
/*
@@ -2516,13 +2518,28 @@ RestoreArchivedFile(char *path, const char *xlogfname,
25162518
}
25172519

25182520
/*
2519-
*remember, we rollforward UNTIL the restore fails so failure here is
2521+
*Remember, we rollforward UNTIL the restore fails so failure here is
25202522
* just part of the process... that makes it difficult to determine
25212523
* whether the restore failed because there isn't an archive to restore,
25222524
* or because the administrator has specified the restore program
25232525
* incorrectly. We have to assume the former.
2526+
*
2527+
* However, if the failure was due to any sort of signal, it's best to
2528+
* punt and abort recovery. (If we "return false" here, upper levels
2529+
* will assume that recovery is complete and start up the database!)
2530+
* It's essential to abort on child SIGINT and SIGQUIT, because per spec
2531+
* system() ignores SIGINT and SIGQUIT while waiting; if we see one of
2532+
* those it's a good bet we should have gotten it too. Aborting on other
2533+
* signals such as SIGTERM seems a good idea as well.
2534+
*
2535+
* Per the Single Unix Spec, shells report exit status > 128 when
2536+
* a called command died on a signal. Also, 126 and 127 are used to
2537+
* report problems such as an unfindable command; treat those as fatal
2538+
* errors too.
25242539
*/
2525-
ereport(DEBUG2,
2540+
signaled=WIFSIGNALED(rc)||WEXITSTATUS(rc)>125;
2541+
2542+
ereport(signaled ?FATAL :DEBUG2,
25262543
(errmsg("could not restore file \"%s\" from archive: return code %d",
25272544
xlogfname,rc)));
25282545

‎src/backend/bootstrap/bootstrap.c

Lines changed: 10 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
* Portions Copyright (c) 1994, Regents of the University of California
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/bootstrap/bootstrap.c,v 1.226 2006/11/2100:49:54 tgl Exp $
11+
* $PostgreSQL: pgsql/src/backend/bootstrap/bootstrap.c,v 1.227 2006/11/2120:59:52 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -500,6 +500,15 @@ bootstrap_signals(void)
500500
{
501501
if (IsUnderPostmaster)
502502
{
503+
/*
504+
* If possible, make this process a group leader, so that the
505+
* postmaster can signal any child processes too.
506+
*/
507+
#ifdefHAVE_SETSID
508+
if (setsid()<0)
509+
elog(FATAL,"setsid() failed: %m");
510+
#endif
511+
503512
/*
504513
* Properly accept or ignore signals the postmaster might send us
505514
*/

‎src/backend/postmaster/autovacuum.c

Lines changed: 12 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -10,7 +10,7 @@
1010
*
1111
*
1212
* IDENTIFICATION
13-
* $PostgreSQL: pgsql/src/backend/postmaster/autovacuum.c,v 1.28 2006/11/05 22:42:09 tgl Exp $
13+
* $PostgreSQL: pgsql/src/backend/postmaster/autovacuum.c,v 1.29 2006/11/21 20:59:52 tgl Exp $
1414
*
1515
*-------------------------------------------------------------------------
1616
*/
@@ -243,6 +243,17 @@ AutoVacMain(int argc, char *argv[])
243243

244244
SetProcessingMode(InitProcessing);
245245

246+
/*
247+
* If possible, make this process a group leader, so that the postmaster
248+
* can signal any child processes too. (autovacuum probably never has
249+
* any child processes, but for consistency we make all postmaster
250+
* child processes do this.)
251+
*/
252+
#ifdefHAVE_SETSID
253+
if (setsid()<0)
254+
elog(FATAL,"setsid() failed: %m");
255+
#endif
256+
246257
/*
247258
* Set up signal handlers.We operate on databases much like a regular
248259
* backend, so we use the same signal handling. See equivalent code in

‎src/backend/postmaster/bgwriter.c

Lines changed: 13 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -37,14 +37,15 @@
3737
*
3838
*
3939
* IDENTIFICATION
40-
* $PostgreSQL: pgsql/src/backend/postmaster/bgwriter.c,v 1.30 2006/11/2100:49:55 tgl Exp $
40+
* $PostgreSQL: pgsql/src/backend/postmaster/bgwriter.c,v 1.31 2006/11/2120:59:52 tgl Exp $
4141
*
4242
*-------------------------------------------------------------------------
4343
*/
4444
#include"postgres.h"
4545

4646
#include<signal.h>
4747
#include<time.h>
48+
#include<unistd.h>
4849

4950
#include"access/xlog_internal.h"
5051
#include"libpq/pqsignal.h"
@@ -170,6 +171,17 @@ BackgroundWriterMain(void)
170171
BgWriterShmem->bgwriter_pid=MyProcPid;
171172
am_bg_writer= true;
172173

174+
/*
175+
* If possible, make this process a group leader, so that the postmaster
176+
* can signal any child processes too. (bgwriter probably never has
177+
* any child processes, but for consistency we make all postmaster
178+
* child processes do this.)
179+
*/
180+
#ifdefHAVE_SETSID
181+
if (setsid()<0)
182+
elog(FATAL,"setsid() failed: %m");
183+
#endif
184+
173185
/*
174186
* Properly accept or ignore signals the postmaster might send us
175187
*

‎src/backend/postmaster/pgarch.c

Lines changed: 25 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -19,7 +19,7 @@
1919
*
2020
*
2121
* IDENTIFICATION
22-
* $PostgreSQL: pgsql/src/backend/postmaster/pgarch.c,v 1.26 2006/11/10 22:32:20 tgl Exp $
22+
* $PostgreSQL: pgsql/src/backend/postmaster/pgarch.c,v 1.27 2006/11/21 20:59:52 tgl Exp $
2323
*
2424
*-------------------------------------------------------------------------
2525
*/
@@ -29,6 +29,7 @@
2929
#include<signal.h>
3030
#include<time.h>
3131
#include<sys/time.h>
32+
#include<sys/wait.h>
3233
#include<unistd.h>
3334

3435
#include"access/xlog_internal.h"
@@ -222,6 +223,15 @@ PgArchiverMain(int argc, char *argv[])
222223

223224
MyProcPid=getpid();/* reset MyProcPid */
224225

226+
/*
227+
* If possible, make this process a group leader, so that the postmaster
228+
* can signal any child processes too.
229+
*/
230+
#ifdefHAVE_SETSID
231+
if (setsid()<0)
232+
elog(FATAL,"setsid() failed: %m");
233+
#endif
234+
225235
/*
226236
* Ignore all signals usually bound to some action in the postmaster,
227237
* except for SIGHUP, SIGUSR1 and SIGQUIT.
@@ -456,9 +466,22 @@ pgarch_archiveXlog(char *xlog)
456466
rc=system(xlogarchcmd);
457467
if (rc!=0)
458468
{
459-
ereport(LOG,
469+
/*
470+
* If either the shell itself, or a called command, died on a signal,
471+
* abort the archiver. We do this because system() ignores SIGINT and
472+
* SIGQUIT while waiting; so a signal is very likely something that
473+
* should have interrupted us too. If we overreact it's no big deal,
474+
* the postmaster will just start the archiver again.
475+
*
476+
* Per the Single Unix Spec, shells report exit status > 128 when
477+
* a called command died on a signal.
478+
*/
479+
boolsignaled=WIFSIGNALED(rc)||WEXITSTATUS(rc)>128;
480+
481+
ereport(signaled ?FATAL :LOG,
460482
(errmsg("archive command \"%s\" failed: return code %d",
461483
xlogarchcmd,rc)));
484+
462485
return false;
463486
}
464487
ereport(LOG,

‎src/backend/postmaster/pgstat.c

Lines changed: 12 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -13,7 +13,7 @@
1313
*
1414
*Copyright (c) 2001-2006, PostgreSQL Global Development Group
1515
*
16-
*$PostgreSQL: pgsql/src/backend/postmaster/pgstat.c,v 1.139 2006/10/04 00:29:56 momjian Exp $
16+
*$PostgreSQL: pgsql/src/backend/postmaster/pgstat.c,v 1.140 2006/11/21 20:59:52 tgl Exp $
1717
* ----------
1818
*/
1919
#include"postgres.h"
@@ -1613,6 +1613,17 @@ PgstatCollectorMain(int argc, char *argv[])
16131613

16141614
MyProcPid=getpid();/* reset MyProcPid */
16151615

1616+
/*
1617+
* If possible, make this process a group leader, so that the postmaster
1618+
* can signal any child processes too. (pgstat probably never has
1619+
* any child processes, but for consistency we make all postmaster
1620+
* child processes do this.)
1621+
*/
1622+
#ifdefHAVE_SETSID
1623+
if (setsid()<0)
1624+
elog(FATAL,"setsid() failed: %m");
1625+
#endif
1626+
16161627
/*
16171628
* Ignore all signals usually bound to some action in the postmaster,
16181629
* except SIGQUIT and SIGALRM.

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