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Commit27c3e3d

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Remove redundant gettimeofday() calls to the extent practical without
changing semantics too much. statement_timestamp is now set immediatelyupon receipt of a client command message, and the various places that usedto do their own gettimeofday() calls to mark command startup are referencedto that instead. I have also made stats_command_string use that samevalue for pg_stat_activity.query_start for both the command itself andits eventual replacement by <IDLE> or <idle in transaction>. There wassome debate about that, but no argument that seemed convincing enough tojustify an extra gettimeofday() call.
1 parent47a37ae commit27c3e3d

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11 files changed

+268
-225
lines changed

11 files changed

+268
-225
lines changed

‎src/backend/access/transam/xact.c

Lines changed: 8 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -10,7 +10,7 @@
1010
*
1111
*
1212
* IDENTIFICATION
13-
* $PostgreSQL: pgsql/src/backend/access/transam/xact.c,v 1.220 2006/04/25 00:25:17 momjian Exp $
13+
* $PostgreSQL: pgsql/src/backend/access/transam/xact.c,v 1.221 2006/06/20 22:51:59 tgl Exp $
1414
*
1515
*-------------------------------------------------------------------------
1616
*/
@@ -167,9 +167,10 @@ static SubTransactionId currentSubTransactionId;
167167
staticCommandIdcurrentCommandId;
168168

169169
/*
170-
* This is the value of now(), ie, the transaction start time.
171-
* This does not change as we enter and exit subtransactions, so we don't
172-
* keep it inside the TransactionState stack.
170+
* xactStartTimestamp is the value of transaction_timestamp().
171+
* stmtStartTimestamp is the value of statement_timestamp().
172+
* These do not change as we enter and exit subtransactions, so we don't
173+
* keep them inside the TransactionState stack.
173174
*/
174175
staticTimestampTzxactStartTimestamp;
175176
staticTimestampTzstmtStartTimestamp;
@@ -1386,7 +1387,9 @@ StartTransaction(void)
13861387
XactLockTableInsert(s->transactionId);
13871388

13881389
/*
1389-
* now() and statement_timestamp() should be the same time
1390+
* set transaction_timestamp() (a/k/a now()). We want this to be the
1391+
* same as the first command's statement_timestamp(), so don't do a
1392+
* fresh GetCurrentTimestamp() call (which'd be expensive anyway).
13901393
*/
13911394
xactStartTimestamp=stmtStartTimestamp;
13921395

‎src/backend/commands/prepare.c

Lines changed: 2 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -10,7 +10,7 @@
1010
* Copyright (c) 2002-2006, PostgreSQL Global Development Group
1111
*
1212
* IDENTIFICATION
13-
* $PostgreSQL: pgsql/src/backend/commands/prepare.c,v 1.52 2006/04/25 14:11:54 momjian Exp $
13+
* $PostgreSQL: pgsql/src/backend/commands/prepare.c,v 1.53 2006/06/20 22:51:59 tgl Exp $
1414
*
1515
*-------------------------------------------------------------------------
1616
*/
@@ -373,7 +373,7 @@ StorePreparedStatement(const char *stmt_name,
373373
entry->plan_list=plan_list;
374374
entry->argtype_list=argtype_list;
375375
entry->context=entrycxt;
376-
entry->prepare_time=GetCurrentTimestamp();
376+
entry->prepare_time=GetCurrentStatementStartTimestamp();
377377
entry->from_sql=from_sql;
378378

379379
MemoryContextSwitchTo(oldcxt);

‎src/backend/postmaster/pgstat.c

Lines changed: 9 additions & 3 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 1.129 2006/06/19 01:51:21 tgl Exp $
16+
*$PostgreSQL: pgsql/src/backend/postmaster/pgstat.c,v 1.130 2006/06/20 22:52:00 tgl Exp $
1717
* ----------
1818
*/
1919
#include"postgres.h"
@@ -1368,8 +1368,14 @@ pgstat_bestart(void)
13681368
/*
13691369
* To minimize the time spent modifying the entry, fetch all the
13701370
* needed data first.
1371+
*
1372+
* If we have a MyProcPort, use its session start time (for consistency,
1373+
* and to save a kernel call).
13711374
*/
1372-
proc_start_timestamp=GetCurrentTimestamp();
1375+
if (MyProcPort)
1376+
proc_start_timestamp=MyProcPort->SessionStartTime;
1377+
else
1378+
proc_start_timestamp=GetCurrentTimestamp();
13731379
userid=GetSessionUserId();
13741380

13751381
/*
@@ -1464,7 +1470,7 @@ pgstat_report_activity(const char *cmd_str)
14641470
* To minimize the time spent modifying the entry, fetch all the
14651471
* needed data first.
14661472
*/
1467-
start_timestamp=GetCurrentTimestamp();
1473+
start_timestamp=GetCurrentStatementStartTimestamp();
14681474

14691475
len=strlen(cmd_str);
14701476
len=pg_mbcliplen(cmd_str,len,PGBE_ACTIVITY_SIZE-1);

‎src/backend/postmaster/postmaster.c

Lines changed: 9 additions & 5 deletions
Original file line numberDiff line numberDiff line change
@@ -37,7 +37,7 @@
3737
*
3838
*
3939
* IDENTIFICATION
40-
* $PostgreSQL: pgsql/src/backend/postmaster/postmaster.c,v 1.487 2006/06/19 01:51:21 tgl Exp $
40+
* $PostgreSQL: pgsql/src/backend/postmaster/postmaster.c,v 1.488 2006/06/20 22:52:00 tgl Exp $
4141
*
4242
* NOTES
4343
*
@@ -99,7 +99,6 @@
9999
#include"commands/async.h"
100100
#include"lib/dllist.h"
101101
#include"libpq/auth.h"
102-
#include"libpq/crypt.h"
103102
#include"libpq/libpq.h"
104103
#include"libpq/pqcomm.h"
105104
#include"libpq/pqsignal.h"
@@ -2609,8 +2608,9 @@ BackendInitialize(Port *port)
26092608

26102609
ClientAuthInProgress= true;/* limit visibility of log messages */
26112610

2612-
/* save start time for end of session reporting */
2613-
gettimeofday(&(port->session_start),NULL);
2611+
/* save process start time */
2612+
port->SessionStartTime=GetCurrentTimestamp();
2613+
port->session_start=timestamptz_to_time_t(port->SessionStartTime);
26142614

26152615
/* set these to empty in case they are needed before we set them up */
26162616
port->remote_host="";
@@ -2749,6 +2749,8 @@ BackendRun(Port *port)
27492749
char**av;
27502750
intmaxac;
27512751
intac;
2752+
longsecs;
2753+
intusecs;
27522754
charprotobuf[32];
27532755
inti;
27542756

@@ -2758,7 +2760,9 @@ BackendRun(Port *port)
27582760
* a new random sequence in the random() library function.
27592761
*/
27602762
random_seed=0;
2761-
srandom((unsignedint) (MyProcPid ^port->session_start.tv_usec));
2763+
/* slightly hacky way to get integer microseconds part of timestamptz */
2764+
TimestampDifference(0,port->SessionStartTime,&secs,&usecs);
2765+
srandom((unsignedint) (MyProcPid ^usecs));
27622766

27632767
/* ----------------
27642768
* Now, build the argv vector that will be given to PostgresMain.

‎src/backend/storage/lmgr/proc.c

Lines changed: 40 additions & 33 deletions
Original file line numberDiff line numberDiff line change
@@ -8,7 +8,7 @@
88
*
99
*
1010
* IDENTIFICATION
11-
* $PostgreSQL: pgsql/src/backend/storage/lmgr/proc.c,v 1.174 2006/04/14 03:38:55 tgl Exp $
11+
* $PostgreSQL: pgsql/src/backend/storage/lmgr/proc.c,v 1.175 2006/06/20 22:52:00 tgl Exp $
1212
*
1313
*-------------------------------------------------------------------------
1414
*/
@@ -42,6 +42,7 @@
4242
#include"storage/proc.h"
4343
#include"storage/procarray.h"
4444
#include"storage/spin.h"
45+
#include"utils/timestamp.h"
4546

4647

4748
/* GUC variables */
@@ -73,7 +74,7 @@ static volatile bool deadlock_timeout_active = false;
7374
volatileboolcancel_from_timeout= false;
7475

7576
/* statement_fin_time is valid only if statement_timeout_active is true */
76-
staticstructtimevalstatement_fin_time;
77+
staticTimestampTzstatement_fin_time;
7778

7879

7980
staticvoidRemoveProcFromArray(intcode,Datumarg);
@@ -1105,29 +1106,32 @@ ProcSendSignal(int pid)
11051106
bool
11061107
enable_sig_alarm(intdelayms,boolis_statement_timeout)
11071108
{
1108-
structtimevalfin_time;
1109+
TimestampTzfin_time;
11091110
structitimervaltimeval;
11101111

1111-
/* Compute target timeout time if we will need it */
1112-
if (is_statement_timeout||statement_timeout_active)
1113-
{
1114-
gettimeofday(&fin_time,NULL);
1115-
fin_time.tv_sec+=delayms /1000;
1116-
fin_time.tv_usec+= (delayms %1000)*1000;
1117-
if (fin_time.tv_usec >=1000000)
1118-
{
1119-
fin_time.tv_sec++;
1120-
fin_time.tv_usec-=1000000;
1121-
}
1122-
}
1123-
11241112
if (is_statement_timeout)
11251113
{
1126-
/* Begin statement-level timeout */
1114+
/*
1115+
* Begin statement-level timeout
1116+
*
1117+
* Note that we compute statement_fin_time with reference to the
1118+
* statement_timestamp, but apply the specified delay without any
1119+
* correction; that is, we ignore whatever time has elapsed since
1120+
* statement_timestamp was set. In the normal case only a small
1121+
* interval will have elapsed and so this doesn't matter, but there
1122+
* are corner cases (involving multi-statement query strings with
1123+
* embedded COMMIT or ROLLBACK) where we might re-initialize the
1124+
* statement timeout long after initial receipt of the message.
1125+
* In such cases the enforcement of the statement timeout will be
1126+
* a bit inconsistent. This annoyance is judged not worth the cost
1127+
* of performing an additional gettimeofday() here.
1128+
*/
11271129
Assert(!deadlock_timeout_active);
1130+
fin_time=GetCurrentStatementStartTimestamp();
1131+
fin_time=TimestampTzPlusMilliseconds(fin_time,delayms);
11281132
statement_fin_time=fin_time;
1129-
statement_timeout_active= true;
11301133
cancel_from_timeout= false;
1134+
statement_timeout_active= true;
11311135
}
11321136
elseif (statement_timeout_active)
11331137
{
@@ -1145,10 +1149,10 @@ enable_sig_alarm(int delayms, bool is_statement_timeout)
11451149
* to the state variables.The deadlock checker may get run earlier
11461150
* than normal, but that does no harm.
11471151
*/
1152+
fin_time=GetCurrentTimestamp();
1153+
fin_time=TimestampTzPlusMilliseconds(fin_time,delayms);
11481154
deadlock_timeout_active= true;
1149-
if (fin_time.tv_sec>statement_fin_time.tv_sec||
1150-
(fin_time.tv_sec==statement_fin_time.tv_sec&&
1151-
fin_time.tv_usec >=statement_fin_time.tv_usec))
1155+
if (fin_time >=statement_fin_time)
11521156
return true;
11531157
}
11541158
else
@@ -1225,16 +1229,14 @@ disable_sig_alarm(bool is_statement_timeout)
12251229
staticbool
12261230
CheckStatementTimeout(void)
12271231
{
1228-
structtimevalnow;
1232+
TimestampTznow;
12291233

12301234
if (!statement_timeout_active)
12311235
return true;/* do nothing if not active */
12321236

1233-
gettimeofday(&now,NULL);
1237+
now=GetCurrentTimestamp();
12341238

1235-
if (now.tv_sec>statement_fin_time.tv_sec||
1236-
(now.tv_sec==statement_fin_time.tv_sec&&
1237-
now.tv_usec >=statement_fin_time.tv_usec))
1239+
if (now >=statement_fin_time)
12381240
{
12391241
/* Time to die */
12401242
statement_timeout_active= false;
@@ -1244,16 +1246,21 @@ CheckStatementTimeout(void)
12441246
else
12451247
{
12461248
/* Not time yet, so (re)schedule the interrupt */
1249+
longsecs;
1250+
intusecs;
12471251
structitimervaltimeval;
12481252

1253+
TimestampDifference(now,statement_fin_time,
1254+
&secs,&usecs);
1255+
/*
1256+
* It's possible that the difference is less than a microsecond;
1257+
* ensure we don't cancel, rather than set, the interrupt.
1258+
*/
1259+
if (secs==0&&usecs==0)
1260+
usecs=1;
12491261
MemSet(&timeval,0,sizeof(structitimerval));
1250-
timeval.it_value.tv_sec=statement_fin_time.tv_sec-now.tv_sec;
1251-
timeval.it_value.tv_usec=statement_fin_time.tv_usec-now.tv_usec;
1252-
if (timeval.it_value.tv_usec<0)
1253-
{
1254-
timeval.it_value.tv_sec--;
1255-
timeval.it_value.tv_usec+=1000000;
1256-
}
1262+
timeval.it_value.tv_sec=secs;
1263+
timeval.it_value.tv_usec=usecs;
12571264
if (setitimer(ITIMER_REAL,&timeval,NULL))
12581265
return false;
12591266
}

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