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Commit00e6a16

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Change the autovacuum launcher to read pg_database directly, rather than
via the "flat files" facility. This requires making it enough like a backendto be able to run transactions; it's no longer an "auxiliary process" butmore like the autovacuum worker processes. Also, its signal handling hasto be brought into line with backends/workers. In particular, since itnow has to handle procsignal.c processing, the special autovac-launcher-onlysignal conditions are moved to SIGUSR2.Alvaro, with some cleanup from Tom
1 parent25ec228 commit00e6a16

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8 files changed

+141
-142
lines changed

8 files changed

+141
-142
lines changed

‎src/backend/postmaster/autovacuum.c

Lines changed: 80 additions & 101 deletions
Original file line numberDiff line numberDiff line change
@@ -35,7 +35,7 @@
3535
* worker and dealt with just by having the worker exit normally. The launcher
3636
* will launch a new worker again later, per schedule.
3737
*
38-
* When the worker is done vacuuming it sendsSIGUSR1 to the launcher.The
38+
* When the worker is done vacuuming it sendsSIGUSR2 to the launcher.The
3939
* launcher then wakes up and is able to launch another worker, if the schedule
4040
* is so tight that a new worker is needed immediately. At this time the
4141
* launcher can also balance the settings for the various remaining workers'
@@ -55,7 +55,7 @@
5555
*
5656
*
5757
* IDENTIFICATION
58-
* $PostgreSQL: pgsql/src/backend/postmaster/autovacuum.c,v 1.103 2009/08/27 17:18:44 alvherre Exp $
58+
* $PostgreSQL: pgsql/src/backend/postmaster/autovacuum.c,v 1.104 2009/08/31 19:40:59 tgl Exp $
5959
*
6060
*-------------------------------------------------------------------------
6161
*/
@@ -67,39 +67,33 @@
6767
#include<time.h>
6868
#include<unistd.h>
6969

70-
#include"access/genam.h"
7170
#include"access/heapam.h"
7271
#include"access/reloptions.h"
7372
#include"access/transam.h"
7473
#include"access/xact.h"
7574
#include"catalog/dependency.h"
76-
#include"catalog/indexing.h"
7775
#include"catalog/namespace.h"
7876
#include"catalog/pg_database.h"
7977
#include"commands/dbcommands.h"
8078
#include"commands/vacuum.h"
81-
#include"libpq/hba.h"
8279
#include"libpq/pqsignal.h"
8380
#include"miscadmin.h"
8481
#include"pgstat.h"
8582
#include"postmaster/autovacuum.h"
8683
#include"postmaster/fork_process.h"
8784
#include"postmaster/postmaster.h"
8885
#include"storage/bufmgr.h"
89-
#include"storage/fd.h"
9086
#include"storage/ipc.h"
9187
#include"storage/pmsignal.h"
9288
#include"storage/proc.h"
93-
#include"storage/procarray.h"
9489
#include"storage/procsignal.h"
9590
#include"storage/sinvaladt.h"
9691
#include"tcop/tcopprot.h"
97-
#include"utils/dynahash.h"
98-
#include"utils/flatfiles.h"
9992
#include"utils/fmgroids.h"
10093
#include"utils/lsyscache.h"
10194
#include"utils/memutils.h"
10295
#include"utils/ps_status.h"
96+
#include"utils/snapmgr.h"
10397
#include"utils/syscache.h"
10498
#include"utils/tqual.h"
10599

@@ -133,7 +127,7 @@ static bool am_autovacuum_worker = false;
133127

134128
/* Flags set by signal handlers */
135129
staticvolatilesig_atomic_tgot_SIGHUP= false;
136-
staticvolatilesig_atomic_tgot_SIGUSR1= false;
130+
staticvolatilesig_atomic_tgot_SIGUSR2= false;
137131
staticvolatilesig_atomic_tgot_SIGTERM= false;
138132

139133
/* Comparison point for determining whether freeze_max_age is exceeded */
@@ -303,9 +297,8 @@ static PgStat_StatTabEntry *get_pgstat_tabentry_relid(Oid relid, bool isshared,
303297
PgStat_StatDBEntry*dbentry);
304298
staticvoidautovac_report_activity(autovac_table*tab);
305299
staticvoidavl_sighup_handler(SIGNAL_ARGS);
306-
staticvoidavl_sigusr1_handler(SIGNAL_ARGS);
300+
staticvoidavl_sigusr2_handler(SIGNAL_ARGS);
307301
staticvoidavl_sigterm_handler(SIGNAL_ARGS);
308-
staticvoidavl_quickdie(SIGNAL_ARGS);
309302
staticvoidautovac_refresh_stats(void);
310303

311304

@@ -407,6 +400,9 @@ AutoVacLauncherMain(int argc, char *argv[])
407400
/* Identify myself via ps */
408401
init_ps_display("autovacuum launcher process","","","");
409402

403+
ereport(LOG,
404+
(errmsg("autovacuum launcher started")));
405+
410406
if (PostAuthDelay)
411407
pg_usleep(PostAuthDelay*1000000L);
412408

@@ -424,20 +420,20 @@ AutoVacLauncherMain(int argc, char *argv[])
424420
#endif
425421

426422
/*
427-
* Set up signal handlers.Since this is an auxiliary process, it has
428-
*particular signal requirements -- no deadlock checker or sinval
429-
*catchup, for example.
423+
* Set up signal handlers.We operate on databases much like a regular
424+
*backend, so we use the same signal handling. See equivalent code in
425+
*tcop/postgres.c.
430426
*/
431427
pqsignal(SIGHUP,avl_sighup_handler);
432-
433-
pqsignal(SIGINT,SIG_IGN);
428+
pqsignal(SIGINT,StatementCancelHandler);
434429
pqsignal(SIGTERM,avl_sigterm_handler);
435-
pqsignal(SIGQUIT,avl_quickdie);
436-
pqsignal(SIGALRM,SIG_IGN);
430+
431+
pqsignal(SIGQUIT,quickdie);
432+
pqsignal(SIGALRM,handle_sig_alarm);
437433

438434
pqsignal(SIGPIPE,SIG_IGN);
439-
pqsignal(SIGUSR1,avl_sigusr1_handler);
440-
pqsignal(SIGUSR2,SIG_IGN);
435+
pqsignal(SIGUSR1,procsignal_sigusr1_handler);
436+
pqsignal(SIGUSR2,avl_sigusr2_handler);
441437
pqsignal(SIGFPE,FloatExceptionHandler);
442438
pqsignal(SIGCHLD,SIG_DFL);
443439

@@ -451,9 +447,13 @@ AutoVacLauncherMain(int argc, char *argv[])
451447
* had to do some stuff with LWLocks).
452448
*/
453449
#ifndefEXEC_BACKEND
454-
InitAuxiliaryProcess();
450+
InitProcess();
455451
#endif
456452

453+
InitPostgres(NULL,InvalidOid,NULL,NULL);
454+
455+
SetProcessingMode(NormalProcessing);
456+
457457
/*
458458
* Create a memory context that we will do all our work in. We do this so
459459
* that we can reset the context during error recovery and thereby avoid
@@ -466,11 +466,10 @@ AutoVacLauncherMain(int argc, char *argv[])
466466
ALLOCSET_DEFAULT_MAXSIZE);
467467
MemoryContextSwitchTo(AutovacMemCxt);
468468

469-
470469
/*
471470
* If an exception is encountered, processing resumes here.
472471
*
473-
* This code isheavily based on bgwriter.c, q.v.
472+
* This code isa stripped down version of PostgresMain error recovery.
474473
*/
475474
if (sigsetjmp(local_sigjmp_buf,1)!=0)
476475
{
@@ -480,17 +479,16 @@ AutoVacLauncherMain(int argc, char *argv[])
480479
/* Prevents interrupts while cleaning up */
481480
HOLD_INTERRUPTS();
482481

482+
/* Forget any pending QueryCancel request */
483+
QueryCancelPending= false;
484+
disable_sig_alarm(true);
485+
QueryCancelPending= false;/* again in case timeout occurred */
486+
483487
/* Report the error to the server log */
484488
EmitErrorReport();
485489

486-
/*
487-
* These operations are really just a minimal subset of
488-
* AbortTransaction().We don't have very many resources to worry
489-
* about, but we do have LWLocks.
490-
*/
491-
LWLockReleaseAll();
492-
AtEOXact_Files();
493-
AtEOXact_HashTables(false);
490+
/* Abort the current transaction in order to recover */
491+
AbortCurrentTransaction();
494492

495493
/*
496494
* Now return to normal top-level context and clear ErrorContext for
@@ -525,9 +523,6 @@ AutoVacLauncherMain(int argc, char *argv[])
525523
/* We can now handle ereport(ERROR) */
526524
PG_exception_stack=&local_sigjmp_buf;
527525

528-
ereport(LOG,
529-
(errmsg("autovacuum launcher started")));
530-
531526
/* must unblock signals before calling rebuild_database_list */
532527
PG_SETMASK(&UnBlockSig);
533528

@@ -561,11 +556,14 @@ AutoVacLauncherMain(int argc, char *argv[])
561556
* necessity for manual cleanup of all postmaster children.
562557
*/
563558
if (!PostmasterIsAlive(true))
564-
exit(1);
559+
proc_exit(1);
565560

566561
launcher_determine_sleep((AutoVacuumShmem->av_freeWorkers!=NULL),
567562
false,&nap);
568563

564+
/* Allow sinval catchup interrupts while sleeping */
565+
EnableCatchupInterrupt();
566+
569567
/*
570568
* Sleep for a while according to schedule.
571569
*
@@ -595,12 +593,14 @@ AutoVacLauncherMain(int argc, char *argv[])
595593
* necessity for manual cleanup of all postmaster children.
596594
*/
597595
if (!PostmasterIsAlive(true))
598-
exit(1);
596+
proc_exit(1);
599597

600-
if (got_SIGTERM||got_SIGHUP||got_SIGUSR1)
598+
if (got_SIGTERM||got_SIGHUP||got_SIGUSR2)
601599
break;
602600
}
603601

602+
DisableCatchupInterrupt();
603+
604604
/* the normal shutdown case */
605605
if (got_SIGTERM)
606606
break;
@@ -610,7 +610,7 @@ AutoVacLauncherMain(int argc, char *argv[])
610610
got_SIGHUP= false;
611611
ProcessConfigFile(PGC_SIGHUP);
612612

613-
/* shutdown requested in config file */
613+
/* shutdown requested in config file? */
614614
if (!AutoVacuumingActive())
615615
break;
616616

@@ -627,9 +627,9 @@ AutoVacLauncherMain(int argc, char *argv[])
627627
* a worker finished, or postmaster signalled failure to start a
628628
* worker
629629
*/
630-
if (got_SIGUSR1)
630+
if (got_SIGUSR2)
631631
{
632-
got_SIGUSR1= false;
632+
got_SIGUSR2= false;
633633

634634
/* rebalance cost limits, if needed */
635635
if (AutoVacuumShmem->av_signal[AutoVacRebalance])
@@ -1306,7 +1306,7 @@ launch_worker(TimestampTz now)
13061306

13071307
/*
13081308
* Called from postmaster to signal a failure to fork a process to become
1309-
* worker.The postmaster should kill(SIGUSR1) the launcher shortly
1309+
* worker.The postmaster should kill(SIGUSR2) the launcher shortly
13101310
* after calling this function.
13111311
*/
13121312
void
@@ -1322,11 +1322,11 @@ avl_sighup_handler(SIGNAL_ARGS)
13221322
got_SIGHUP= true;
13231323
}
13241324

1325-
/*SIGUSR1: a worker is up and running, or just finished, or failed to fork */
1325+
/*SIGUSR2: a worker is up and running, or just finished, or failed to fork */
13261326
staticvoid
1327-
avl_sigusr1_handler(SIGNAL_ARGS)
1327+
avl_sigusr2_handler(SIGNAL_ARGS)
13281328
{
1329-
got_SIGUSR1= true;
1329+
got_SIGUSR2= true;
13301330
}
13311331

13321332
/* SIGTERM: time to die */
@@ -1336,38 +1336,6 @@ avl_sigterm_handler(SIGNAL_ARGS)
13361336
got_SIGTERM= true;
13371337
}
13381338

1339-
/*
1340-
* avl_quickdie occurs when signalled SIGQUIT from postmaster.
1341-
*
1342-
* Some backend has bought the farm, so we need to stop what we're doing
1343-
* and exit.
1344-
*/
1345-
staticvoid
1346-
avl_quickdie(SIGNAL_ARGS)
1347-
{
1348-
PG_SETMASK(&BlockSig);
1349-
1350-
/*
1351-
* We DO NOT want to run proc_exit() callbacks -- we're here because
1352-
* shared memory may be corrupted, so we don't want to try to clean up our
1353-
* transaction. Just nail the windows shut and get out of town. Now that
1354-
* there's an atexit callback to prevent third-party code from breaking
1355-
* things by calling exit() directly, we have to reset the callbacks
1356-
* explicitly to make this work as intended.
1357-
*/
1358-
on_exit_reset();
1359-
1360-
/*
1361-
* Note we do exit(2) not exit(0).This is to force the postmaster into a
1362-
* system reset cycle if some idiot DBA sends a manual SIGQUIT to a random
1363-
* backend. This is necessary precisely because we don't clean up our
1364-
* shared memory state. (The "dead man switch" mechanism in pmsignal.c
1365-
* should ensure the postmaster sees this as a crash, too, but no harm in
1366-
* being doubly sure.)
1367-
*/
1368-
exit(2);
1369-
}
1370-
13711339

13721340
/********************************************************************
13731341
* AUTOVACUUM WORKER CODE
@@ -1590,7 +1558,7 @@ AutoVacWorkerMain(int argc, char *argv[])
15901558

15911559
/* wake up the launcher */
15921560
if (AutoVacuumShmem->av_launcherpid!=0)
1593-
kill(AutoVacuumShmem->av_launcherpid,SIGUSR1);
1561+
kill(AutoVacuumShmem->av_launcherpid,SIGUSR2);
15941562
}
15951563
else
15961564
{
@@ -1784,46 +1752,57 @@ autovac_balance_cost(void)
17841752

17851753
/*
17861754
* get_database_list
1755+
*Return a list of all databases found in pg_database.
17871756
*
1788-
*Return a list of all databases. Note we cannot use pg_database,
1789-
*because we aren't connected; we use the flat database file.
1757+
* Note: this is the only function in which the autovacuum launcher uses a
1758+
* transaction. Although we aren't attached to any particular database and
1759+
* therefore can't access most catalogs, we do have enough infrastructure
1760+
* to do a seqscan on pg_database.
17901761
*/
17911762
staticList*
17921763
get_database_list(void)
17931764
{
1794-
char*filename;
17951765
List*dblist=NIL;
1796-
charthisname[NAMEDATALEN];
1797-
FILE*db_file;
1798-
Oiddb_id;
1799-
Oiddb_tablespace;
1800-
TransactionIddb_frozenxid;
1801-
1802-
filename=database_getflatfilename();
1803-
db_file=AllocateFile(filename,"r");
1804-
if (db_file==NULL)
1805-
ereport(FATAL,
1806-
(errcode_for_file_access(),
1807-
errmsg("could not open file \"%s\": %m",filename)));
1766+
Relationrel;
1767+
HeapScanDescscan;
1768+
HeapTupletup;
1769+
1770+
/*
1771+
* Start a transaction so we can access pg_database, and get a snapshot.
1772+
* We don't have a use for the snapshot itself, but we're interested in
1773+
* the secondary effect that it sets RecentGlobalXmin. (This is critical
1774+
* for anything that reads heap pages, because HOT may decide to prune
1775+
* them even if the process doesn't attempt to modify any tuples.)
1776+
*/
1777+
StartTransactionCommand();
1778+
(void)GetTransactionSnapshot();
1779+
1780+
/* Allocate our results in AutovacMemCxt, not transaction context */
1781+
MemoryContextSwitchTo(AutovacMemCxt);
18081782

1809-
while (read_pg_database_line(db_file,thisname,&db_id,
1810-
&db_tablespace,&db_frozenxid))
1783+
rel=heap_open(DatabaseRelationId,AccessShareLock);
1784+
scan=heap_beginscan(rel,SnapshotNow,0,NULL);
1785+
1786+
while (HeapTupleIsValid(tup=heap_getnext(scan,ForwardScanDirection)))
18111787
{
1812-
avw_dbase*avdb;
1788+
Form_pg_databasepgdatabase= (Form_pg_database)GETSTRUCT(tup);
1789+
avw_dbase*avdb;
18131790

18141791
avdb= (avw_dbase*)palloc(sizeof(avw_dbase));
18151792

1816-
avdb->adw_datid=db_id;
1817-
avdb->adw_name=pstrdup(thisname);
1818-
avdb->adw_frozenxid=db_frozenxid;
1793+
avdb->adw_datid=HeapTupleGetOid(tup);
1794+
avdb->adw_name=pstrdup(NameStr(pgdatabase->datname));
1795+
avdb->adw_frozenxid=pgdatabase->datfrozenxid;
18191796
/* this gets set later: */
18201797
avdb->adw_entry=NULL;
18211798

18221799
dblist=lappend(dblist,avdb);
18231800
}
18241801

1825-
FreeFile(db_file);
1826-
pfree(filename);
1802+
heap_endscan(scan);
1803+
heap_close(rel,AccessShareLock);
1804+
1805+
CommitTransactionCommand();
18271806

18281807
returndblist;
18291808
}

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