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Commit0914ae1

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Remove the pgstats logic for delaying destruction of stats table entries.
Per recent discussion, this seems to be making the stats less accuraterather than more so, particularly on Windows where PID values may bereused very quickly. Patch by Peter Brant.
1 parent0bc2a8c commit0914ae1

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3 files changed

+33
-198
lines changed

3 files changed

+33
-198
lines changed

‎src/backend/postmaster/autovacuum.c‎

Lines changed: 5 additions & 14 deletions
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 1.15 2006/03/07 17:32:22 tgl Exp $
13+
* $PostgreSQL: pgsql/src/backend/postmaster/autovacuum.c,v 1.16 2006/04/06 20:38:00 tgl Exp $
1414
*
1515
*-------------------------------------------------------------------------
1616
*/
@@ -384,19 +384,7 @@ AutoVacMain(int argc, char *argv[])
384384
continue;
385385

386386
/*
387-
* Don't try to access a database that was dropped. This could only
388-
* happen if we read the pg_database flat file right before it was
389-
* modified, after the database was dropped from the pg_database
390-
* table. (This is of course a not-very-bulletproof test, but it's
391-
* cheap to make. If we do mistakenly choose a recently dropped
392-
* database, InitPostgres will fail and we'll drop out until the next
393-
* autovac run.)
394-
*/
395-
if (tmp->entry->destroy!=0)
396-
continue;
397-
398-
/*
399-
* Else remember the db with oldest autovac time.
387+
* Remember the db with oldest autovac time.
400388
*/
401389
if (db==NULL||
402390
tmp->entry->last_autovac_time<db->entry->last_autovac_time)
@@ -417,6 +405,9 @@ AutoVacMain(int argc, char *argv[])
417405

418406
/*
419407
* Connect to the selected database
408+
*
409+
* Note: if we have selected a just-deleted database (due to using
410+
* stale stats info), we'll fail and exit here.
420411
*/
421412
InitPostgres(db->name,NULL);
422413
SetProcessingMode(NormalProcessing);

‎src/backend/postmaster/pgstat.c‎

Lines changed: 23 additions & 162 deletions
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 1.121 2006/03/05 15:58:36 momjian Exp $
16+
*$PostgreSQL: pgsql/src/backend/postmaster/pgstat.c,v 1.122 2006/04/06 20:38:00 tgl Exp $
1717
* ----------
1818
*/
1919
#include"postgres.h"
@@ -69,12 +69,6 @@
6969
#definePGSTAT_STAT_INTERVAL500/* How often to write the status file;
7070
* in milliseconds. */
7171

72-
#definePGSTAT_DESTROY_DELAY10000/* How long to keep destroyed objects
73-
* known, to give delayed UDP packets
74-
* time to arrive; in milliseconds. */
75-
76-
#definePGSTAT_DESTROY_COUNT(PGSTAT_DESTROY_DELAY / PGSTAT_STAT_INTERVAL)
77-
7872
#definePGSTAT_RESTART_INTERVAL 60/* How often to attempt to restart a
7973
* failed statistics collector; in
8074
* seconds. */
@@ -141,7 +135,6 @@ static intpgStatXactRollback = 0;
141135

142136
staticTransactionIdpgStatDBHashXact=InvalidTransactionId;
143137
staticHTAB*pgStatDBHash=NULL;
144-
staticHTAB*pgStatBeDead=NULL;
145138
staticPgStat_StatBeEntry*pgStatBeTable=NULL;
146139
staticintpgStatNumBackends=0;
147140

@@ -1552,7 +1545,6 @@ PgstatCollectorMain(int argc, char *argv[])
15521545
intreadPipe;
15531546
intlen=0;
15541547
structitimervaltimeout;
1555-
HASHCTLhash_ctl;
15561548
boolneed_timer= false;
15571549

15581550
MyProcPid=getpid();/* reset MyProcPid */
@@ -1614,16 +1606,6 @@ PgstatCollectorMain(int argc, char *argv[])
16141606
pgStatRunningInCollector= true;
16151607
pgstat_read_statsfile(&pgStatDBHash,InvalidOid,NULL,NULL);
16161608

1617-
/*
1618-
* Create the dead backend hashtable
1619-
*/
1620-
memset(&hash_ctl,0,sizeof(hash_ctl));
1621-
hash_ctl.keysize=sizeof(int);
1622-
hash_ctl.entrysize=sizeof(PgStat_StatBeDead);
1623-
hash_ctl.hash=tag_hash;
1624-
pgStatBeDead=hash_create("Dead Backends",PGSTAT_BE_HASH_SIZE,
1625-
&hash_ctl,HASH_ELEM |HASH_FUNCTION);
1626-
16271609
/*
16281610
* Create the known backends table
16291611
*/
@@ -2085,7 +2067,6 @@ static int
20852067
pgstat_add_backend(PgStat_MsgHdr*msg)
20862068
{
20872069
PgStat_StatBeEntry*beentry;
2088-
PgStat_StatBeDead*deadbe;
20892070

20902071
/*
20912072
* Check that the backend ID is valid
@@ -2111,32 +2092,13 @@ pgstat_add_backend(PgStat_MsgHdr *msg)
21112092
if (beentry->procpid>0&&beentry->procpid==msg->m_procpid)
21122093
return0;
21132094

2114-
/*
2115-
* Lookup if this backend is known to be dead. This can be caused due to
2116-
* messages arriving in the wrong order - e.g. postmaster's BETERM message
2117-
* might have arrived before we received all the backends stats messages,
2118-
* or even a new backend with the same backendid was faster in sending his
2119-
* BESTART.
2120-
*
2121-
* If the backend is known to be dead, we ignore this add.
2122-
*/
2123-
deadbe= (PgStat_StatBeDead*)hash_search(pgStatBeDead,
2124-
(void*)&(msg->m_procpid),
2125-
HASH_FIND,NULL);
2126-
if (deadbe)
2127-
return1;
2128-
2129-
/*
2130-
* Backend isn't known to be dead. If it's slot is currently used, we have
2131-
* to kick out the old backend.
2132-
*/
2133-
if (beentry->procpid>0)
2134-
pgstat_sub_backend(beentry->procpid);
2135-
21362095
/* Must be able to distinguish between empty and non-empty slots */
21372096
Assert(msg->m_procpid>0);
21382097

2139-
/* Put this new backend into the slot */
2098+
/*
2099+
* Put this new backend into the slot (possibly overwriting an old entry,
2100+
* if we missed its BETERM or the BETERM hasn't arrived yet).
2101+
*/
21402102
beentry->procpid=msg->m_procpid;
21412103
beentry->start_timestamp=GetCurrentTimestamp();
21422104
beentry->activity_start_timestamp=0;
@@ -2185,7 +2147,6 @@ pgstat_get_db_entry(Oid databaseid, bool create)
21852147
result->n_xact_rollback=0;
21862148
result->n_blocks_fetched=0;
21872149
result->n_blocks_hit=0;
2188-
result->destroy=0;
21892150
result->last_autovac_time=0;
21902151

21912152
memset(&hash_ctl,0,sizeof(hash_ctl));
@@ -2211,8 +2172,6 @@ static void
22112172
pgstat_sub_backend(intprocpid)
22122173
{
22132174
inti;
2214-
PgStat_StatBeDead*deadbe;
2215-
boolfound;
22162175

22172176
/*
22182177
* Search in the known-backends table for the slot containing this PID.
@@ -2222,28 +2181,7 @@ pgstat_sub_backend(int procpid)
22222181
if (pgStatBeTable[i].procpid==procpid)
22232182
{
22242183
/*
2225-
* That's him. Add an entry to the known to be dead backends. Due
2226-
* to possible misorder in the arrival of UDP packets it's
2227-
* possible that even if we know the backend is dead, there could
2228-
* still be messages queued that arrive later. Those messages must
2229-
* not cause our number of backends statistics to get screwed up,
2230-
* so we remember for a couple of seconds that this PID is dead
2231-
* and ignore them (only the counting of backends, not the table
2232-
* access stats they sent).
2233-
*/
2234-
deadbe= (PgStat_StatBeDead*)hash_search(pgStatBeDead,
2235-
(void*)&procpid,
2236-
HASH_ENTER,
2237-
&found);
2238-
2239-
if (!found)
2240-
{
2241-
deadbe->backendid=i+1;
2242-
deadbe->destroy=PGSTAT_DESTROY_COUNT;
2243-
}
2244-
2245-
/*
2246-
* Declare the backend slot empty.
2184+
* That's him. Mark the backend slot empty.
22472185
*/
22482186
pgStatBeTable[i].procpid=0;
22492187
return;
@@ -2270,7 +2208,6 @@ pgstat_write_statsfile(void)
22702208
HASH_SEQ_STATUStstat;
22712209
PgStat_StatDBEntry*dbentry;
22722210
PgStat_StatTabEntry*tabentry;
2273-
PgStat_StatBeDead*deadbe;
22742211
FILE*fpout;
22752212
inti;
22762213
int32format_id;
@@ -2300,31 +2237,6 @@ pgstat_write_statsfile(void)
23002237
hash_seq_init(&hstat,pgStatDBHash);
23012238
while ((dbentry= (PgStat_StatDBEntry*)hash_seq_search(&hstat))!=NULL)
23022239
{
2303-
/*
2304-
* If this database is marked destroyed, count down and do so if it
2305-
* reaches 0.
2306-
*/
2307-
if (dbentry->destroy>0)
2308-
{
2309-
if (--(dbentry->destroy)==0)
2310-
{
2311-
if (dbentry->tables!=NULL)
2312-
hash_destroy(dbentry->tables);
2313-
2314-
if (hash_search(pgStatDBHash,
2315-
(void*)&(dbentry->databaseid),
2316-
HASH_REMOVE,NULL)==NULL)
2317-
ereport(ERROR,
2318-
(errmsg("database hash table corrupted "
2319-
"during cleanup --- abort")));
2320-
}
2321-
2322-
/*
2323-
* Don't include statistics for it.
2324-
*/
2325-
continue;
2326-
}
2327-
23282240
/*
23292241
* Write out the DB entry including the number of live backends.
23302242
* We don't write the tables pointer since it's of no use to any
@@ -2339,30 +2251,6 @@ pgstat_write_statsfile(void)
23392251
hash_seq_init(&tstat,dbentry->tables);
23402252
while ((tabentry= (PgStat_StatTabEntry*)hash_seq_search(&tstat))!=NULL)
23412253
{
2342-
/*
2343-
* If table entry marked for destruction, same as above for the
2344-
* database entry.
2345-
*/
2346-
if (tabentry->destroy>0)
2347-
{
2348-
if (--(tabentry->destroy)==0)
2349-
{
2350-
if (hash_search(dbentry->tables,
2351-
(void*)&(tabentry->tableid),
2352-
HASH_REMOVE,NULL)==NULL)
2353-
ereport(ERROR,
2354-
(errmsg("tables hash table for "
2355-
"database %u corrupted during "
2356-
"cleanup --- abort",
2357-
dbentry->databaseid)));
2358-
}
2359-
continue;
2360-
}
2361-
2362-
/*
2363-
* At least we think this is still a live table. Emit its access
2364-
* stats.
2365-
*/
23662254
fputc('T',fpout);
23672255
fwrite(tabentry,sizeof(PgStat_StatTabEntry),1,fpout);
23682256
}
@@ -2428,26 +2316,6 @@ pgstat_write_statsfile(void)
24282316
PGSTAT_STAT_TMPFILE,PGSTAT_STAT_FILENAME)));
24292317
unlink(PGSTAT_STAT_TMPFILE);
24302318
}
2431-
2432-
/*
2433-
* Clear out the dead backends table
2434-
*/
2435-
hash_seq_init(&hstat,pgStatBeDead);
2436-
while ((deadbe= (PgStat_StatBeDead*)hash_seq_search(&hstat))!=NULL)
2437-
{
2438-
/*
2439-
* Count down the destroy delay and remove entries where it reaches 0.
2440-
*/
2441-
if (--(deadbe->destroy) <=0)
2442-
{
2443-
if (hash_search(pgStatBeDead,
2444-
(void*)&(deadbe->procpid),
2445-
HASH_REMOVE,NULL)==NULL)
2446-
ereport(ERROR,
2447-
(errmsg("dead-server-process hash table corrupted "
2448-
"during cleanup --- abort")));
2449-
}
2450-
}
24512319
}
24522320

24532321
/*
@@ -2595,7 +2463,6 @@ pgstat_read_statsfile(HTAB **dbhash, Oid onlydb,
25952463

25962464
memcpy(dbentry,&dbbuf,sizeof(PgStat_StatDBEntry));
25972465
dbentry->tables=NULL;
2598-
dbentry->destroy=0;
25992466
dbentry->n_backends=0;
26002467

26012468
/*
@@ -3005,12 +2872,8 @@ pgstat_recv_tabstat(PgStat_MsgTabstat *msg, int len)
30052872
dbentry=pgstat_get_db_entry(msg->m_databaseid, true);
30062873

30072874
/*
3008-
* If the database is marked for destroy, this is a delayed UDP packet and
3009-
* not worth being counted.
2875+
* Update database-wide stats.
30102876
*/
3011-
if (dbentry->destroy>0)
3012-
return;
3013-
30142877
dbentry->n_xact_commit+= (PgStat_Counter) (msg->m_xact_commit);
30152878
dbentry->n_xact_rollback+= (PgStat_Counter) (msg->m_xact_rollback);
30162879

@@ -3043,8 +2906,6 @@ pgstat_recv_tabstat(PgStat_MsgTabstat *msg, int len)
30432906

30442907
tabentry->blocks_fetched=tabmsg[i].t_blocks_fetched;
30452908
tabentry->blocks_hit=tabmsg[i].t_blocks_hit;
3046-
3047-
tabentry->destroy=0;
30482909
}
30492910
else
30502911
{
@@ -3085,7 +2946,6 @@ static void
30852946
pgstat_recv_tabpurge(PgStat_MsgTabpurge*msg,intlen)
30862947
{
30872948
PgStat_StatDBEntry*dbentry;
3088-
PgStat_StatTabEntry*tabentry;
30892949
inti;
30902950

30912951
/*
@@ -3102,23 +2962,15 @@ pgstat_recv_tabpurge(PgStat_MsgTabpurge *msg, int len)
31022962
if (!dbentry|| !dbentry->tables)
31032963
return;
31042964

3105-
/*
3106-
* If the database is marked for destroy, this is a delayed UDP packet and
3107-
* the tables will go away at DB destruction.
3108-
*/
3109-
if (dbentry->destroy>0)
3110-
return;
3111-
31122965
/*
31132966
* Process all table entries in the message.
31142967
*/
31152968
for (i=0;i<msg->m_nentries;i++)
31162969
{
3117-
tabentry= (PgStat_StatTabEntry*)hash_search(dbentry->tables,
3118-
(void*)&(msg->m_tableid[i]),
3119-
HASH_FIND,NULL);
3120-
if (tabentry)
3121-
tabentry->destroy=PGSTAT_DESTROY_COUNT;
2970+
/* Remove from hashtable if present; we don't care if it's not. */
2971+
(void)hash_search(dbentry->tables,
2972+
(void*)&(msg->m_tableid[i]),
2973+
HASH_REMOVE,NULL);
31222974
}
31232975
}
31242976

@@ -3146,10 +2998,20 @@ pgstat_recv_dropdb(PgStat_MsgDropdb *msg, int len)
31462998
dbentry=pgstat_get_db_entry(msg->m_databaseid, false);
31472999

31483000
/*
3149-
*Mark the database for destruction.
3001+
*If found, remove it.
31503002
*/
31513003
if (dbentry)
3152-
dbentry->destroy=PGSTAT_DESTROY_COUNT;
3004+
{
3005+
if (dbentry->tables!=NULL)
3006+
hash_destroy(dbentry->tables);
3007+
3008+
if (hash_search(pgStatDBHash,
3009+
(void*)&(dbentry->databaseid),
3010+
HASH_REMOVE,NULL)==NULL)
3011+
ereport(ERROR,
3012+
(errmsg("database hash table corrupted "
3013+
"during cleanup --- abort")));
3014+
}
31533015
}
31543016

31553017

@@ -3191,7 +3053,6 @@ pgstat_recv_resetcounter(PgStat_MsgResetcounter *msg, int len)
31913053
dbentry->n_xact_rollback=0;
31923054
dbentry->n_blocks_fetched=0;
31933055
dbentry->n_blocks_hit=0;
3194-
dbentry->destroy=0;
31953056

31963057
memset(&hash_ctl,0,sizeof(hash_ctl));
31973058
hash_ctl.keysize=sizeof(Oid);

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