Tom Lane wrote:
> Alvaro Herrera <alvhe...@commandprompt.com> writes:
> > Tom Lane wrote:
> >> This just seems truly messy :-(. Let me see if I can find something
> >> cleaner.
>
> > I was considering having InitPostgres be an umbrella function, so that
> > extant callers stay as today, but the various underlying pieces are
> > skipped depending on who's calling. For example I didn't like the bit
> > about starting a transaction or not depending on whether it was the
> > launcher.
>
> Yeah. If you have InitPostgres know that much about the AV launcher's
> requirements, it's not clear why it shouldn't just know everything.
> Having it return with the initial transaction still open just seems
> completely horrid.
How about this?
> While I was looking at this I wondered whether
> RelationCacheInitializePhase2 really needs to be inside the startup
> transaction at all. I think it could probably be moved up before
> that. However, if the AV launcher has to do GetTransactionSnapshot
> then it's not clear that improves matters anyway.
Well, the difference is that the initial transaction would be a few
microsec shorter ... not sure if that matters.
--
Alvaro Herrera http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.
Index: src/backend/postmaster/autovacuum.c
===================================================================
RCS file: /home/alvherre/Code/cvs/pgsql/src/backend/postmaster/autovacuum.c,v
retrieving revision 1.103
diff -c -p -r1.103 autovacuum.c
*** src/backend/postmaster/autovacuum.c 27 Aug 2009 17:18:44 -0000 1.103
--- src/backend/postmaster/autovacuum.c 31 Aug 2009 15:49:14 -0000
*************** AutoVacLauncherMain(int argc, char *argv
*** 424,432 ****
#endif
/*
! * Set up signal handlers. Since this is an auxiliary process, it has
! * particular signal requirements -- no deadlock checker or sinval
! * catchup, for example.
*/
pqsignal(SIGHUP, avl_sighup_handler);
--- 424,432 ----
#endif
/*
! * Set up signal handlers. We operate on databases much like a regular
! * backend, so we use the same signal handling. See equivalent code in
! * tcop/postgres.c.
*/
pqsignal(SIGHUP, avl_sighup_handler);
*************** AutoVacLauncherMain(int argc, char *argv
*** 451,459 ****
* had to do some stuff with LWLocks).
*/
#ifndef EXEC_BACKEND
! InitAuxiliaryProcess();
#endif
/*
* Create a memory context that we will do all our work in. We do this so
* that we can reset the context during error recovery and thereby avoid
--- 451,461 ----
* had to do some stuff with LWLocks).
*/
#ifndef EXEC_BACKEND
! InitProcess();
#endif
+ InitPostgres(NULL, InvalidOid, NULL, NULL);
+
/*
* Create a memory context that we will do all our work in. We do this so
* that we can reset the context during error recovery and thereby avoid
*************** AutoVacLauncherMain(int argc, char *argv
*** 470,476 ****
/*
* If an exception is encountered, processing resumes here.
*
! * This code is heavily based on bgwriter.c, q.v.
*/
if (sigsetjmp(local_sigjmp_buf, 1) != 0)
{
--- 472,478 ----
/*
* If an exception is encountered, processing resumes here.
*
! * This code is a stripped down version of PostgresMain error recovery.
*/
if (sigsetjmp(local_sigjmp_buf, 1) != 0)
{
*************** AutoVacLauncherMain(int argc, char *argv
*** 483,496 ****
/* Report the error to the server log */
EmitErrorReport();
! /*
! * These operations are really just a minimal subset of
! * AbortTransaction(). We don't have very many resources to worry
! * about, but we do have LWLocks.
! */
! LWLockReleaseAll();
! AtEOXact_Files();
! AtEOXact_HashTables(false);
/*
* Now return to normal top-level context and clear ErrorContext for
--- 485,492 ----
/* Report the error to the server log */
EmitErrorReport();
! /* Abort the current transaction in order to recover */
! AbortCurrentTransaction();
/*
* Now return to normal top-level context and clear ErrorContext for
*************** autovac_balance_cost(void)
*** 1784,1829 ****
/*
* get_database_list
*
! * Return a list of all databases. Note we cannot use pg_database,
! * because we aren't connected; we use the flat database file.
*/
static List *
get_database_list(void)
{
- char *filename;
List *dblist = NIL;
! char thisname[NAMEDATALEN];
! FILE *db_file;
! Oid db_id;
! Oid db_tablespace;
! TransactionId db_frozenxid;
!
! filename = database_getflatfilename();
! db_file = AllocateFile(filename, "r");
! if (db_file == NULL)
! ereport(FATAL,
! (errcode_for_file_access(),
! errmsg("could not open file \"%s\": %m", filename)));
! while (read_pg_database_line(db_file, thisname, &db_id,
! &db_tablespace, &db_frozenxid))
{
! avw_dbase *avdb;
avdb = (avw_dbase *) palloc(sizeof(avw_dbase));
! avdb->adw_datid = db_id;
! avdb->adw_name = pstrdup(thisname);
! avdb->adw_frozenxid = db_frozenxid;
/* this gets set later: */
avdb->adw_entry = NULL;
dblist = lappend(dblist, avdb);
}
! FreeFile(db_file);
! pfree(filename);
return dblist;
}
--- 1780,1825 ----
/*
* get_database_list
+ * Return a list of all databases found in pg_database.
*
! * Note: this is the only function in which the autovacuum launcher uses a
! * transaction.
*/
static List *
get_database_list(void)
{
List *dblist = NIL;
! Relation rel;
! HeapScanDesc scan;
! HeapTuple tup;
! StartTransactionCommand();
!
! MemoryContextSwitchTo(AutovacMemCxt);
!
! rel = heap_open(DatabaseRelationId, AccessShareLock);
! scan = heap_beginscan(rel, SnapshotNow, 0, NULL);
!
! while (HeapTupleIsValid(tup = heap_getnext(scan, ForwardScanDirection)))
{
! Form_pg_database pgdatabase = (Form_pg_database) GETSTRUCT(tup);
! avw_dbase *avdb;
avdb = (avw_dbase *) palloc(sizeof(avw_dbase));
! avdb->adw_datid = HeapTupleGetOid(tup);
! avdb->adw_name = pstrdup(NameStr(pgdatabase->datname));
! avdb->adw_frozenxid = pgdatabase->datfrozenxid;
/* this gets set later: */
avdb->adw_entry = NULL;
dblist = lappend(dblist, avdb);
}
! heap_endscan(scan);
! heap_close(rel, AccessShareLock);
!
! CommitTransactionCommand();
return dblist;
}
Index: src/backend/postmaster/postmaster.c
===================================================================
RCS file: /home/alvherre/Code/cvs/pgsql/src/backend/postmaster/postmaster.c,v
retrieving revision 1.593
diff -c -p -r1.593 postmaster.c
*** src/backend/postmaster/postmaster.c 29 Aug 2009 19:26:51 -0000 1.593
--- src/backend/postmaster/postmaster.c 31 Aug 2009 13:37:29 -0000
*************** SubPostmasterMain(int argc, char *argv[]
*** 3865,3871 ****
InitShmemAccess(UsedShmemSegAddr);
/* Need a PGPROC to run CreateSharedMemoryAndSemaphores */
! InitAuxiliaryProcess();
/* Attach process to shared data structures */
CreateSharedMemoryAndSemaphores(false, 0);
--- 3865,3871 ----
InitShmemAccess(UsedShmemSegAddr);
/* Need a PGPROC to run CreateSharedMemoryAndSemaphores */
! InitProcess();
/* Attach process to shared data structures */
CreateSharedMemoryAndSemaphores(false, 0);
Index: src/backend/storage/lmgr/proc.c
===================================================================
RCS file: /home/alvherre/Code/cvs/pgsql/src/backend/storage/lmgr/proc.c,v
retrieving revision 1.208
diff -c -p -r1.208 proc.c
*** src/backend/storage/lmgr/proc.c 12 Aug 2009 20:53:30 -0000 1.208
--- src/backend/storage/lmgr/proc.c 31 Aug 2009 13:36:56 -0000
*************** ProcGlobalShmemSize(void)
*** 102,109 ****
size = add_size(size, sizeof(PROC_HDR));
/* AuxiliaryProcs */
size = add_size(size, mul_size(NUM_AUXILIARY_PROCS, sizeof(PGPROC)));
! /* MyProcs, including autovacuum */
! size = add_size(size, mul_size(MaxBackends, sizeof(PGPROC)));
/* ProcStructLock */
size = add_size(size, sizeof(slock_t));
--- 102,109 ----
size = add_size(size, sizeof(PROC_HDR));
/* AuxiliaryProcs */
size = add_size(size, mul_size(NUM_AUXILIARY_PROCS, sizeof(PGPROC)));
! /* MyProcs, including autovacuum workers and launcher */
! size = add_size(size, mul_size(MaxBackends + 1, sizeof(PGPROC)));
/* ProcStructLock */
size = add_size(size, sizeof(slock_t));
*************** InitProcGlobal(void)
*** 192,204 ****
ProcGlobal->freeProcs = &procs[i];
}
! procs = (PGPROC *) ShmemAlloc((autovacuum_max_workers) * sizeof(PGPROC));
if (!procs)
ereport(FATAL,
(errcode(ERRCODE_OUT_OF_MEMORY),
errmsg("out of shared memory")));
! MemSet(procs, 0, autovacuum_max_workers * sizeof(PGPROC));
! for (i = 0; i < autovacuum_max_workers; i++)
{
PGSemaphoreCreate(&(procs[i].sem));
procs[i].links.next = (SHM_QUEUE *) ProcGlobal->autovacFreeProcs;
--- 192,204 ----
ProcGlobal->freeProcs = &procs[i];
}
! procs = (PGPROC *) ShmemAlloc((autovacuum_max_workers + 1) * sizeof(PGPROC));
if (!procs)
ereport(FATAL,
(errcode(ERRCODE_OUT_OF_MEMORY),
errmsg("out of shared memory")));
! MemSet(procs, 0, (autovacuum_max_workers + 1) * sizeof(PGPROC));
! for (i = 0; i < autovacuum_max_workers + 1; i++)
{
PGSemaphoreCreate(&(procs[i].sem));
procs[i].links.next = (SHM_QUEUE *) ProcGlobal->autovacFreeProcs;
*************** InitProcess(void)
*** 248,261 ****
set_spins_per_delay(procglobal->spins_per_delay);
! if (IsAutoVacuumWorkerProcess())
MyProc = procglobal->autovacFreeProcs;
else
MyProc = procglobal->freeProcs;
if (MyProc != NULL)
{
! if (IsAutoVacuumWorkerProcess())
procglobal->autovacFreeProcs = (PGPROC *) MyProc->links.next;
else
procglobal->freeProcs = (PGPROC *) MyProc->links.next;
--- 248,261 ----
set_spins_per_delay(procglobal->spins_per_delay);
! if (IsAnyAutoVacuumProcess())
MyProc = procglobal->autovacFreeProcs;
else
MyProc = procglobal->freeProcs;
if (MyProc != NULL)
{
! if (IsAnyAutoVacuumProcess())
procglobal->autovacFreeProcs = (PGPROC *) MyProc->links.next;
else
procglobal->freeProcs = (PGPROC *) MyProc->links.next;
*************** InitProcess(void)
*** 280,286 ****
* child; this is so that the postmaster can detect it if we exit without
* cleaning up.
*/
! if (IsUnderPostmaster)
MarkPostmasterChildActive();
/*
--- 280,286 ----
* child; this is so that the postmaster can detect it if we exit without
* cleaning up.
*/
! if (IsUnderPostmaster && !IsAutoVacuumLauncherProcess())
MarkPostmasterChildActive();
/*
*************** InitProcess(void)
*** 299,304 ****
--- 299,305 ----
MyProc->roleId = InvalidOid;
MyProc->inCommit = false;
MyProc->vacuumFlags = 0;
+ /* NB -- autovac launcher does not set this flag to avoid getting killed */
if (IsAutoVacuumWorkerProcess())
MyProc->vacuumFlags |= PROC_IS_AUTOVACUUM;
MyProc->lwWaiting = false;
*************** InitAuxiliaryProcess(void)
*** 429,435 ****
MyProc->databaseId = InvalidOid;
MyProc->roleId = InvalidOid;
MyProc->inCommit = false;
- /* we don't set the "is autovacuum" flag in the launcher */
MyProc->vacuumFlags = 0;
MyProc->lwWaiting = false;
MyProc->lwExclusive = false;
--- 430,435 ----
*************** ProcKill(int code, Datum arg)
*** 596,602 ****
SpinLockAcquire(ProcStructLock);
/* Return PGPROC structure (and semaphore) to freelist */
! if (IsAutoVacuumWorkerProcess())
{
MyProc->links.next = (SHM_QUEUE *) procglobal->autovacFreeProcs;
procglobal->autovacFreeProcs = MyProc;
--- 596,602 ----
SpinLockAcquire(ProcStructLock);
/* Return PGPROC structure (and semaphore) to freelist */
! if (IsAnyAutoVacuumProcess())
{
MyProc->links.next = (SHM_QUEUE *) procglobal->autovacFreeProcs;
procglobal->autovacFreeProcs = MyProc;
*************** ProcKill(int code, Datum arg)
*** 619,625 ****
* This process is no longer present in shared memory in any meaningful
* way, so tell the postmaster we've cleaned up acceptably well.
*/
! if (IsUnderPostmaster)
MarkPostmasterChildInactive();
/* wake autovac launcher if needed -- see comments in FreeWorkerInfo */
--- 619,625 ----
* This process is no longer present in shared memory in any meaningful
* way, so tell the postmaster we've cleaned up acceptably well.
*/
! if (IsUnderPostmaster && !IsAutoVacuumLauncherProcess())
MarkPostmasterChildInactive();
/* wake autovac launcher if needed -- see comments in FreeWorkerInfo */
Index: src/backend/utils/init/postinit.c
===================================================================
RCS file: /home/alvherre/Code/cvs/pgsql/src/backend/utils/init/postinit.c,v
retrieving revision 1.195
diff -c -p -r1.195 postinit.c
*** src/backend/utils/init/postinit.c 29 Aug 2009 19:26:51 -0000 1.195
--- src/backend/utils/init/postinit.c 31 Aug 2009 15:48:10 -0000
*************** InitPostgres(const char *in_dbname, Oid
*** 552,557 ****
--- 552,560 ----
* Start a new transaction here before first access to db, and get a
* snapshot. We don't have a use for the snapshot itself, but we're
* interested in the secondary effect that it sets RecentGlobalXmin.
+ * This is critical for anything that reads heap pages, because HOT
+ * may decide to prune them even if the process doesn't attempt to
+ * modify it.
*/
if (!bootstrap)
{
*************** InitPostgres(const char *in_dbname, Oid
*** 565,570 ****
--- 568,577 ----
*/
RelationCacheInitializePhase2();
+ /* The autovacuum launcher is done here */
+ if (IsAutoVacuumLauncherProcess())
+ goto done;
+
/*
* Set up the global variables holding database id and default tablespace.
* But note we won't actually try to touch the database just yet.
*************** InitPostgres(const char *in_dbname, Oid
*** 774,779 ****
--- 781,787 ----
if (!bootstrap)
pgstat_bestart();
+ done:
/* close the transaction we started above */
if (!bootstrap)
CommitTransactionCommand();
Index: src/backend/utils/misc/guc.c
===================================================================
RCS file: /home/alvherre/Code/cvs/pgsql/src/backend/utils/misc/guc.c,v
retrieving revision 1.513
diff -c -p -r1.513 guc.c
*** src/backend/utils/misc/guc.c 31 Aug 2009 02:23:22 -0000 1.513
--- src/backend/utils/misc/guc.c 31 Aug 2009 03:07:47 -0000
*************** static struct config_int ConfigureNamesI
*** 1335,1341 ****
* Note: MaxBackends is limited to INT_MAX/4 because some places compute
* 4*MaxBackends without any overflow check. This check is made in
* assign_maxconnections, since MaxBackends is computed as MaxConnections
! * plus autovacuum_max_workers.
*
* Likewise we have to limit NBuffers to INT_MAX/2.
*/
--- 1335,1341 ----
* Note: MaxBackends is limited to INT_MAX/4 because some places compute
* 4*MaxBackends without any overflow check. This check is made in
* assign_maxconnections, since MaxBackends is computed as MaxConnections
! * plus autovacuum_max_workers plus one (for the autovacuum launcher).
*
* Likewise we have to limit NBuffers to INT_MAX/2.
*/
*************** assign_maxconnections(int newval, bool d
*** 7574,7580 ****
return false;
if (doit)
! MaxBackends = newval + autovacuum_max_workers;
return true;
}
--- 7574,7580 ----
return false;
if (doit)
! MaxBackends = newval + autovacuum_max_workers + 1;
return true;
}
*************** assign_autovacuum_max_workers(int newval
*** 7586,7592 ****
return false;
if (doit)
! MaxBackends = newval + MaxConnections;
return true;
}
--- 7586,7592 ----
return false;
if (doit)
! MaxBackends = newval + MaxConnections + 1;
return true;
}
Index: src/include/postmaster/autovacuum.h
===================================================================
RCS file: /home/alvherre/Code/cvs/pgsql/src/include/postmaster/autovacuum.h,v
retrieving revision 1.15
diff -c -p -r1.15 autovacuum.h
*** src/include/postmaster/autovacuum.h 1 Jan 2009 17:24:01 -0000 1.15
--- src/include/postmaster/autovacuum.h 31 Aug 2009 03:29:17 -0000
*************** extern int Log_autovacuum_min_duration;
*** 37,42 ****
--- 37,44 ----
extern bool AutoVacuumingActive(void);
extern bool IsAutoVacuumLauncherProcess(void);
extern bool IsAutoVacuumWorkerProcess(void);
+ #define IsAnyAutoVacuumProcess() (IsAutoVacuumLauncherProcess() || \
+ IsAutoVacuumWorkerProcess())
/* Functions to start autovacuum process, called from postmaster */
extern void autovac_init(void);
Index: src/include/storage/proc.h
===================================================================
RCS file: /home/alvherre/Code/cvs/pgsql/src/include/storage/proc.h,v
retrieving revision 1.113
diff -c -p -r1.113 proc.h
*** src/include/storage/proc.h 12 Aug 2009 20:53:30 -0000 1.113
--- src/include/storage/proc.h 31 Aug 2009 03:08:42 -0000
*************** typedef struct PROC_HDR
*** 141,152 ****
* We set aside some extra PGPROC structures for auxiliary processes,
* ie things that aren't full-fledged backends but need shmem access.
*
! * Background writer, WAL writer, and autovacuum launcher run during
! * normal operation. Startup process also consumes one slot, but WAL
! * writer and autovacuum launcher are launched only after it has
* exited.
*/
! #define NUM_AUXILIARY_PROCS 3
/* configurable options */
--- 141,151 ----
* We set aside some extra PGPROC structures for auxiliary processes,
* ie things that aren't full-fledged backends but need shmem access.
*
! * Background writer and WAL writer run during normal operation. Startup
! * process also consumes one slot, but WAL writer is launched only after it has
* exited.
*/
! #define NUM_AUXILIARY_PROCS 2
/* configurable options */
--
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