postgres/src/backend/access/rmgrdesc/xlogdesc.c
Robert Haas 6bc8ef0b7f Add new GUC, max_worker_processes, limiting number of bgworkers.
In 9.3, there's no particular limit on the number of bgworkers;
instead, we just count up the number that are actually registered,
and use that to set MaxBackends.  However, that approach causes
problems for Hot Standby, which needs both MaxBackends and the
size of the lock table to be the same on the standby as on the
master, yet it may not be desirable to run the same bgworkers in
both places.  9.3 handles that by failing to notice the problem,
which will probably work fine in nearly all cases anyway, but is
not theoretically sound.

A further problem with simply counting the number of registered
workers is that new workers can't be registered without a
postmaster restart.  This is inconvenient for administrators,
since bouncing the postmaster causes an interruption of service.
Moreover, there are a number of applications for background
processes where, by necessity, the background process must be
started on the fly (e.g. parallel query).  While this patch
doesn't actually make it possible to register new background
workers after startup time, it's a necessary prerequisite.

Patch by me.  Review by Michael Paquier.
2013-07-04 11:24:24 -04:00

146 lines
3.9 KiB
C

/*-------------------------------------------------------------------------
*
* xlogdesc.c
* rmgr descriptor routines for access/transam/xlog.c
*
* Portions Copyright (c) 1996-2013, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
*
* IDENTIFICATION
* src/backend/access/rmgrdesc/xlogdesc.c
*
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/xlog.h"
#include "access/xlog_internal.h"
#include "catalog/pg_control.h"
#include "common/relpath.h"
#include "utils/guc.h"
#include "utils/timestamp.h"
/*
* GUC support
*/
const struct config_enum_entry wal_level_options[] = {
{"minimal", WAL_LEVEL_MINIMAL, false},
{"archive", WAL_LEVEL_ARCHIVE, false},
{"hot_standby", WAL_LEVEL_HOT_STANDBY, false},
{NULL, 0, false}
};
void
xlog_desc(StringInfo buf, uint8 xl_info, char *rec)
{
uint8 info = xl_info & ~XLR_INFO_MASK;
if (info == XLOG_CHECKPOINT_SHUTDOWN ||
info == XLOG_CHECKPOINT_ONLINE)
{
CheckPoint *checkpoint = (CheckPoint *) rec;
appendStringInfo(buf, "checkpoint: redo %X/%X; "
"tli %u; prev tli %u; fpw %s; xid %u/%u; oid %u; multi %u; offset %u; "
"oldest xid %u in DB %u; oldest multi %u in DB %u; "
"oldest running xid %u; %s",
(uint32) (checkpoint->redo >> 32), (uint32) checkpoint->redo,
checkpoint->ThisTimeLineID,
checkpoint->PrevTimeLineID,
checkpoint->fullPageWrites ? "true" : "false",
checkpoint->nextXidEpoch, checkpoint->nextXid,
checkpoint->nextOid,
checkpoint->nextMulti,
checkpoint->nextMultiOffset,
checkpoint->oldestXid,
checkpoint->oldestXidDB,
checkpoint->oldestMulti,
checkpoint->oldestMultiDB,
checkpoint->oldestActiveXid,
(info == XLOG_CHECKPOINT_SHUTDOWN) ? "shutdown" : "online");
}
else if (info == XLOG_NOOP)
{
appendStringInfo(buf, "xlog no-op");
}
else if (info == XLOG_NEXTOID)
{
Oid nextOid;
memcpy(&nextOid, rec, sizeof(Oid));
appendStringInfo(buf, "nextOid: %u", nextOid);
}
else if (info == XLOG_SWITCH)
{
appendStringInfo(buf, "xlog switch");
}
else if (info == XLOG_RESTORE_POINT)
{
xl_restore_point *xlrec = (xl_restore_point *) rec;
appendStringInfo(buf, "restore point: %s", xlrec->rp_name);
}
else if (info == XLOG_FPI)
{
BkpBlock *bkp = (BkpBlock *) rec;
appendStringInfo(buf, "full-page image: %s block %u",
relpathperm(bkp->node, bkp->fork),
bkp->block);
}
else if (info == XLOG_BACKUP_END)
{
XLogRecPtr startpoint;
memcpy(&startpoint, rec, sizeof(XLogRecPtr));
appendStringInfo(buf, "backup end: %X/%X",
(uint32) (startpoint >> 32), (uint32) startpoint);
}
else if (info == XLOG_PARAMETER_CHANGE)
{
xl_parameter_change xlrec;
const char *wal_level_str;
const struct config_enum_entry *entry;
memcpy(&xlrec, rec, sizeof(xl_parameter_change));
/* Find a string representation for wal_level */
wal_level_str = "?";
for (entry = wal_level_options; entry->name; entry++)
{
if (entry->val == xlrec.wal_level)
{
wal_level_str = entry->name;
break;
}
}
appendStringInfo(buf, "parameter change: max_connections=%d max_worker_processes=%d max_prepared_xacts=%d max_locks_per_xact=%d wal_level=%s",
xlrec.MaxConnections,
xlrec.max_worker_processes,
xlrec.max_prepared_xacts,
xlrec.max_locks_per_xact,
wal_level_str);
}
else if (info == XLOG_FPW_CHANGE)
{
bool fpw;
memcpy(&fpw, rec, sizeof(bool));
appendStringInfo(buf, "full_page_writes: %s", fpw ? "true" : "false");
}
else if (info == XLOG_END_OF_RECOVERY)
{
xl_end_of_recovery xlrec;
memcpy(&xlrec, rec, sizeof(xl_end_of_recovery));
appendStringInfo(buf, "end_of_recovery: tli %u; prev tli %u; time %s",
xlrec.ThisTimeLineID, xlrec.PrevTimeLineID,
timestamptz_to_str(xlrec.end_time));
}
else
appendStringInfo(buf, "UNKNOWN");
}