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Avoid unnecessary work when stats collection is disabled. Tighten
search loop in pgstat_initstats. Per report from Gavin Sherry.
1 parent e3d97d7 commit 1c6702f

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+108
-101
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+108
-101
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‎src/backend/postmaster/pgstat.c

Lines changed: 108 additions & 101 deletions
Original file line numberDiff line numberDiff line change
@@ -13,7 +13,7 @@
1313
*
1414
* Copyright (c) 2001-2003, PostgreSQL Global Development Group
1515
*
16-
* $Header: /cvsroot/pgsql/src/backend/postmaster/pgstat.c,v 1.42 2003/08/04 00:43:21 momjian Exp $
16+
* $Header: /cvsroot/pgsql/src/backend/postmaster/pgstat.c,v 1.43 2003/08/12 16:21:18 tgl Exp $
1717
* ----------
1818
*/
1919
#include "postgres.h"
@@ -156,7 +156,8 @@ pgstat_init(void)
156156
/*
157157
* Force start of collector daemon if something to collect
158158
*/
159-
if (pgstat_collect_querystring || pgstat_collect_tuplelevel ||
159+
if (pgstat_collect_querystring ||
160+
pgstat_collect_tuplelevel ||
160161
pgstat_collect_blocklevel)
161162
pgstat_collect_startcollector = true;
162163

@@ -536,34 +537,38 @@ void
536537
pgstat_report_tabstat(void)
537538
{
538539
int i;
539-
int n;
540-
int len;
541-
542-
if (!pgstat_collect_querystring && !pgstat_collect_tuplelevel &&
543-
!pgstat_collect_blocklevel)
544-
return;
545540

546-
if (pgStatSock < 0)
541+
if (pgStatSock < 0 ||
542+
!(pgstat_collect_querystring ||
543+
pgstat_collect_tuplelevel ||
544+
pgstat_collect_blocklevel))
545+
{
546+
/* Not reporting stats, so just flush whatever we have */
547+
pgStatTabstatUsed = 0;
547548
return;
549+
}
548550

549551
/*
550552
* For each message buffer used during the last query set the header
551553
* fields and send it out.
552554
*/
553555
for (i = 0; i < pgStatTabstatUsed; i++)
554556
{
555-
n = pgStatTabstatMessages[i]->m_nentries;
557+
PgStat_MsgTabstat *tsmsg = pgStatTabstatMessages[i];
558+
int n;
559+
int len;
560+
561+
n = tsmsg->m_nentries;
556562
len = offsetof(PgStat_MsgTabstat, m_entry[0]) +
557563
n * sizeof(PgStat_TableEntry);
558564

559-
pgStatTabstatMessages[i]->m_xact_commit = pgStatXactCommit;
560-
pgStatTabstatMessages[i]->m_xact_rollback = pgStatXactRollback;
565+
tsmsg->m_xact_commit = pgStatXactCommit;
566+
tsmsg->m_xact_rollback = pgStatXactRollback;
561567
pgStatXactCommit = 0;
562568
pgStatXactRollback = 0;
563569

564-
pgstat_setheader(&pgStatTabstatMessages[i]->m_hdr,
565-
PGSTAT_MTYPE_TABSTAT);
566-
pgstat_send(pgStatTabstatMessages[i], len);
570+
pgstat_setheader(&tsmsg->m_hdr, PGSTAT_MTYPE_TABSTAT);
571+
pgstat_send(tsmsg, len);
567572
}
568573

569574
pgStatTabstatUsed = 0;
@@ -802,6 +807,53 @@ pgstat_ping(void)
802807
pgstat_send(&msg, sizeof(msg));
803808
}
804809

810+
/*
811+
* Create or enlarge the pgStatTabstatMessages array
812+
*/
813+
static bool
814+
more_tabstat_space(void)
815+
{
816+
PgStat_MsgTabstat *newMessages;
817+
PgStat_MsgTabstat **msgArray;
818+
int newAlloc = pgStatTabstatAlloc + TABSTAT_QUANTUM;
819+
int i;
820+
821+
/* Create (another) quantum of message buffers */
822+
newMessages = (PgStat_MsgTabstat *)
823+
malloc(sizeof(PgStat_MsgTabstat) * TABSTAT_QUANTUM);
824+
if (newMessages == NULL)
825+
{
826+
ereport(LOG,
827+
(errcode(ERRCODE_OUT_OF_MEMORY),
828+
errmsg("out of memory")));
829+
return false;
830+
}
831+
832+
/* Create or enlarge the pointer array */
833+
if (pgStatTabstatMessages == NULL)
834+
msgArray = (PgStat_MsgTabstat **)
835+
malloc(sizeof(PgStat_MsgTabstat *) * newAlloc);
836+
else
837+
msgArray = (PgStat_MsgTabstat **)
838+
realloc(pgStatTabstatMessages,
839+
sizeof(PgStat_MsgTabstat *) * newAlloc);
840+
if (msgArray == NULL)
841+
{
842+
free(newMessages);
843+
ereport(LOG,
844+
(errcode(ERRCODE_OUT_OF_MEMORY),
845+
errmsg("out of memory")));
846+
return false;
847+
}
848+
849+
MemSet(newMessages, 0, sizeof(PgStat_MsgTabstat) * TABSTAT_QUANTUM);
850+
for (i = 0; i < TABSTAT_QUANTUM; i++)
851+
msgArray[pgStatTabstatAlloc + i] = newMessages++;
852+
pgStatTabstatMessages = msgArray;
853+
pgStatTabstatAlloc = newAlloc;
854+
855+
return true;
856+
}
805857

806858
/* ----------
807859
* pgstat_initstats() -
@@ -815,8 +867,9 @@ pgstat_ping(void)
815867
void
816868
pgstat_initstats(PgStat_Info *stats, Relation rel)
817869
{
818-
PgStat_TableEntry *useent;
819870
Oid rel_id = rel->rd_id;
871+
PgStat_TableEntry *useent;
872+
PgStat_MsgTabstat *tsmsg;
820873
int mb;
821874
int i;
822875

@@ -828,69 +881,39 @@ pgstat_initstats(PgStat_Info *stats, Relation rel)
828881
stats->heap_scan_counted = FALSE;
829882
stats->index_scan_counted = FALSE;
830883

831-
if (pgStatSock < 0)
884+
if (pgStatSock < 0 ||
885+
!(pgstat_collect_tuplelevel ||
886+
pgstat_collect_blocklevel))
832887
{
833888
stats->no_stats = TRUE;
834889
return;
835890
}
836891

837-
/*
838-
* On the first of all calls create some message buffers.
839-
*/
840-
if (pgStatTabstatMessages == NULL)
841-
{
842-
PgStat_MsgTabstat *newMessages;
843-
PgStat_MsgTabstat **msgArray;
844-
845-
newMessages = (PgStat_MsgTabstat *)
846-
malloc(sizeof(PgStat_MsgTabstat) * TABSTAT_QUANTUM);
847-
if (newMessages == NULL)
848-
{
849-
ereport(LOG,
850-
(errcode(ERRCODE_OUT_OF_MEMORY),
851-
errmsg("out of memory")));
852-
return;
853-
}
854-
msgArray = (PgStat_MsgTabstat **)
855-
malloc(sizeof(PgStat_MsgTabstat *) * TABSTAT_QUANTUM);
856-
if (msgArray == NULL)
857-
{
858-
free(newMessages);
859-
ereport(LOG,
860-
(errcode(ERRCODE_OUT_OF_MEMORY),
861-
errmsg("out of memory")));
862-
return;
863-
}
864-
MemSet(newMessages, 0, sizeof(PgStat_MsgTabstat) * TABSTAT_QUANTUM);
865-
for (i = 0; i < TABSTAT_QUANTUM; i++)
866-
msgArray[i] = newMessages++;
867-
pgStatTabstatMessages = msgArray;
868-
pgStatTabstatAlloc = TABSTAT_QUANTUM;
869-
}
870-
871892
/*
872893
* Search the already-used message slots for this relation.
873894
*/
874895
for (mb = 0; mb < pgStatTabstatUsed; mb++)
875896
{
876-
for (i = 0; i < pgStatTabstatMessages[mb]->m_nentries; i++)
897+
tsmsg = pgStatTabstatMessages[mb];
898+
899+
for (i = tsmsg->m_nentries; --i >= 0; )
877900
{
878-
if (pgStatTabstatMessages[mb]->m_entry[i].t_id == rel_id)
901+
if (tsmsg->m_entry[i].t_id == rel_id)
879902
{
880-
stats->tabentry = (void *) &(pgStatTabstatMessages[mb]->m_entry[i]);
903+
stats->tabentry = (void *) &(tsmsg->m_entry[i]);
881904
return;
882905
}
883906
}
884907

885-
if (pgStatTabstatMessages[mb]->m_nentries >= PGSTAT_NUM_TABENTRIES)
908+
if (tsmsg->m_nentries >= PGSTAT_NUM_TABENTRIES)
886909
continue;
887910

888911
/*
889912
* Not found, but found a message buffer with an empty slot
890913
* instead. Fine, let's use this one.
891914
*/
892-
i = pgStatTabstatMessages[mb]->m_nentries++;
893-
useent = &pgStatTabstatMessages[mb]->m_entry[i];
915+
i = tsmsg->m_nentries++;
916+
useent = &tsmsg->m_entry[i];
894917
MemSet(useent, 0, sizeof(PgStat_TableEntry));
895918
useent->t_id = rel_id;
896919
stats->tabentry = (void *) useent;
@@ -902,43 +925,21 @@ pgstat_initstats(PgStat_Info *stats, Relation rel)
902925
*/
903926
if (pgStatTabstatUsed >= pgStatTabstatAlloc)
904927
{
905-
int newAlloc = pgStatTabstatAlloc + TABSTAT_QUANTUM;
906-
PgStat_MsgTabstat *newMessages;
907-
PgStat_MsgTabstat **msgArray;
908-
909-
newMessages = (PgStat_MsgTabstat *)
910-
malloc(sizeof(PgStat_MsgTabstat) * TABSTAT_QUANTUM);
911-
if (newMessages == NULL)
912-
{
913-
ereport(LOG,
914-
(errcode(ERRCODE_OUT_OF_MEMORY),
915-
errmsg("out of memory")));
916-
return;
917-
}
918-
msgArray = (PgStat_MsgTabstat **)
919-
realloc(pgStatTabstatMessages,
920-
sizeof(PgStat_MsgTabstat *) * newAlloc);
921-
if (msgArray == NULL)
928+
if (!more_tabstat_space())
922929
{
923-
free(newMessages);
924-
ereport(LOG,
925-
(errcode(ERRCODE_OUT_OF_MEMORY),
926-
errmsg("out of memory")));
930+
stats->no_stats = TRUE;
927931
return;
928932
}
929-
MemSet(newMessages, 0, sizeof(PgStat_MsgTabstat) * TABSTAT_QUANTUM);
930-
for (i = 0; i < TABSTAT_QUANTUM; i++)
931-
msgArray[pgStatTabstatAlloc + i] = newMessages++;
932-
pgStatTabstatMessages = msgArray;
933-
pgStatTabstatAlloc = newAlloc;
933+
Assert(pgStatTabstatUsed < pgStatTabstatAlloc);
934934
}
935935

936936
/*
937937
* Use the first entry of the next message buffer.
938938
*/
939939
mb = pgStatTabstatUsed++;
940-
pgStatTabstatMessages[mb]->m_nentries = 1;
941-
useent = &pgStatTabstatMessages[mb]->m_entry[0];
940+
tsmsg = pgStatTabstatMessages[mb];
941+
tsmsg->m_nentries = 1;
942+
useent = &tsmsg->m_entry[0];
942943
MemSet(useent, 0, sizeof(PgStat_TableEntry));
943944
useent->t_id = rel_id;
944945
stats->tabentry = (void *) useent;
@@ -954,8 +955,9 @@ pgstat_initstats(PgStat_Info *stats, Relation rel)
954955
void
955956
pgstat_count_xact_commit(void)
956957
{
957-
if (!pgstat_collect_querystring && !pgstat_collect_tuplelevel &&
958-
!pgstat_collect_blocklevel)
958+
if (!(pgstat_collect_querystring ||
959+
pgstat_collect_tuplelevel ||
960+
pgstat_collect_blocklevel))
959961
return;
960962

961963
pgStatXactCommit++;
@@ -965,13 +967,15 @@ pgstat_count_xact_commit(void)
965967
* message buffer used without slots, causing the next report to tell
966968
* new xact-counters.
967969
*/
968-
if (pgStatTabstatAlloc > 0)
970+
if (pgStatTabstatAlloc == 0)
969971
{
970-
if (pgStatTabstatUsed == 0)
971-
{
972-
pgStatTabstatUsed++;
973-
pgStatTabstatMessages[0]->m_nentries = 0;
974-
}
972+
if (!more_tabstat_space())
973+
return;
974+
}
975+
if (pgStatTabstatUsed == 0)
976+
{
977+
pgStatTabstatUsed++;
978+
pgStatTabstatMessages[0]->m_nentries = 0;
975979
}
976980
}
977981

@@ -985,8 +989,9 @@ pgstat_count_xact_commit(void)
985989
void
986990
pgstat_count_xact_rollback(void)
987991
{
988-
if (!pgstat_collect_querystring && !pgstat_collect_tuplelevel &&
989-
!pgstat_collect_blocklevel)
992+
if (!(pgstat_collect_querystring ||
993+
pgstat_collect_tuplelevel ||
994+
pgstat_collect_blocklevel))
990995
return;
991996

992997
pgStatXactRollback++;
@@ -996,13 +1001,15 @@ pgstat_count_xact_rollback(void)
9961001
* message buffer used without slots, causing the next report to tell
9971002
* new xact-counters.
9981003
*/
999-
if (pgStatTabstatAlloc > 0)
1004+
if (pgStatTabstatAlloc == 0)
10001005
{
1001-
if (pgStatTabstatUsed == 0)
1002-
{
1003-
pgStatTabstatUsed++;
1004-
pgStatTabstatMessages[0]->m_nentries = 0;
1005-
}
1006+
if (!more_tabstat_space())
1007+
return;
1008+
}
1009+
if (pgStatTabstatUsed == 0)
1010+
{
1011+
pgStatTabstatUsed++;
1012+
pgStatTabstatMessages[0]->m_nentries = 0;
10061013
}
10071014
}
10081015

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