Wrong result with pgbench -C option?

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http://momjian.postgresql.org/cgi-bin/pgpatches_hold

---------------------------------------------------------------------------

Yoshiyuki Asaba wrote:

Hi,

I ran pgbench with -C option. Here is an output.

% pgbench -C -c 10 -t 100 bench
starting vacuum...end.
transaction type: TPC-B (sort of)
scaling factor: 1
number of clients: 10
number of transactions per client: 100
number of transactions actually processed: 1000/1000
tps = 83.209663 (including connections establishing)
tps = 83.209663 (excluding connections establishing)

The first tps was equal to the second tps. I think it is wrong because
pgbench with -C option connects per transaction.

The attached patch calculates total connection time. Here is an output
with revised pgbench.

% ./pgbench -C -c 10 -t 100 bench
starting vacuum...end.
transaction type: TPC-B (sort of)
scaling factor: 1
number of clients: 10
number of transactions per client: 100
number of transactions actually processed: 1000/1000
tps = 108.410991 (including connections establishing)
tps = 228.657561 (excluding connections establishing)

Regards,
--
Yoshiyuki Asaba
y-asaba@sraoss.co.jp

Index: pgbench.c
===================================================================
RCS file: /projects/cvsroot/pgsql/contrib/pgbench/pgbench.c,v
retrieving revision 1.74
diff -c -r1.74 pgbench.c
*** pgbench.c	15 Nov 2007 21:14:31 -0000	1.74
--- pgbench.c	6 Dec 2007 03:04:35 -0000
***************
*** 185,190 ****
--- 185,223 ----
"SELECT abalance FROM accounts WHERE aid = :aid;\n"
};

+ /* Connection overhead time */
+ static struct timeval conn_total_time = {0, 0};
+ 
+ /* Calculate total time */
+ static void
+ addTime(struct timeval *t1, struct timeval *t2, struct timeval *result)
+ {
+ 	int sec = t1->tv_sec + t2->tv_sec;
+ 	int usec = t1->tv_usec + t2->tv_usec;
+ 	if (usec >= 1000000)
+ 	{
+ 		usec -= 1000000;
+ 		sec++;
+ 	}
+ 	result->tv_sec = sec;
+ 	result->tv_usec = usec;
+ }
+ 
+ /* Calculate time difference */
+ static void
+ diffTime(struct timeval *t1, struct timeval *t2, struct timeval *result)
+ {
+ 	int sec = t1->tv_sec - t2->tv_sec;
+ 	int usec = t1->tv_usec - t2->tv_usec;
+ 	if (usec < 0)
+ 	{
+ 		usec += 1000000;
+ 		sec--;
+ 	}
+ 	result->tv_sec = sec;
+ 	result->tv_usec = usec;
+ }
+ 
static void
usage(void)
{
***************
*** 543,548 ****
--- 576,584 ----

if (st->con == NULL)
{
+ 		struct timeval t1, t2, t3;
+ 
+ 		gettimeofday(&t1, NULL);
if ((st->con = doConnect()) == NULL)
{
fprintf(stderr, "Client %d aborted in establishing connection.\n",
***************
*** 552,557 ****
--- 588,596 ----
st->con = NULL;
return;
}
+ 		gettimeofday(&t2, NULL);
+ 		diffTime(&t2, &t1, &t3);
+ 		addTime(&conn_total_time, &t3, &conn_total_time);
}

if (use_log && st->state == 0)
***************
*** 1162,1169 ****
static void
printResults(
int ttype, CState * state,
! 			 struct timeval * tv1, struct timeval * tv2,
! 			 struct timeval * tv3)
{
double		t1,
t2;
--- 1201,1207 ----
static void
printResults(
int ttype, CState * state,
! 			 struct timeval * start_time, struct timeval * end_time)
{
double		t1,
t2;
***************
*** 1174,1183 ****
for (i = 0; i < nclients; i++)
normal_xacts += state[i].cnt;

! t1 = (tv3->tv_sec - tv1->tv_sec) * 1000000.0 + (tv3->tv_usec - tv1->tv_usec);
t1 = normal_xacts * 1000000.0 / t1;

! t2 = (tv3->tv_sec - tv2->tv_sec) * 1000000.0 + (tv3->tv_usec - tv2->tv_usec);
t2 = normal_xacts * 1000000.0 / t2;

if (ttype == 0)
--- 1212,1222 ----
for (i = 0; i < nclients; i++)
normal_xacts += state[i].cnt;

! t1 = (end_time->tv_sec - start_time->tv_sec) * 1000000.0 + (end_time->tv_usec - start_time->tv_usec);
t1 = normal_xacts * 1000000.0 / t1;

! t2 = (end_time->tv_sec - start_time->tv_sec - conn_total_time.tv_sec) * 1000000.0 +
! (end_time->tv_usec - start_time->tv_usec - conn_total_time.tv_usec);
t2 = normal_xacts * 1000000.0 / t2;

if (ttype == 0)
***************
*** 1213,1222 ****

CState *state; /* status of clients */

! struct timeval tv1; /* start up time */
! struct timeval tv2; /* after establishing all connections to the
! * backend */
! struct timeval tv3; /* end time */

int i;

--- 1252,1259 ----

CState *state; /* status of clients */

! struct timeval start_time; /* start up time */
! struct timeval end_time; /* end time */

int i;

***************
*** 1533,1546 ****
PQfinish(con);

/* set random seed */
! gettimeofday(&tv1, NULL);
! srandom((unsigned int) tv1.tv_usec);

/* get start up time */
! gettimeofday(&tv1, NULL);

if (is_connect == 0)
{
/* make connections to the database */
for (i = 0; i < nclients; i++)
{
--- 1570,1585 ----
PQfinish(con);

/* set random seed */
! gettimeofday(&start_time, NULL);
! srandom((unsigned int) start_time.tv_usec);

/* get start up time */
! gettimeofday(&start_time, NULL);

if (is_connect == 0)
{
+ struct timeval t, now;
+
/* make connections to the database */
for (i = 0; i < nclients; i++)
{
***************
*** 1548,1558 ****
if ((state[i].con = doConnect()) == NULL)
exit(1);
}
}

- 	/* time after connections set up */
- 	gettimeofday(&tv2, NULL);
- 
/* process bultin SQL scripts */
switch (ttype)
{
--- 1587,1598 ----
if ((state[i].con = doConnect()) == NULL)
exit(1);
}
+ 		/* time after connections set up */
+ 		gettimeofday(&now, NULL);
+ 		diffTime(&now, &start_time, &t);
+ 		addTime(&conn_total_time, &t, &conn_total_time);
}

/* process bultin SQL scripts */
switch (ttype)
{
***************
*** 1599,1606 ****
{						/* all done ? */
disconnect_all(state);
/* get end time */
! 			gettimeofday(&tv3, NULL);
! 			printResults(ttype, state, &tv1, &tv2, &tv3);
if (LOGFILE)
fclose(LOGFILE);
exit(0);
--- 1639,1646 ----
{						/* all done ? */
disconnect_all(state);
/* get end time */
! 			gettimeofday(&end_time, NULL);
! 			printResults(ttype, state, &start_time, &end_time);
if (LOGFILE)
fclose(LOGFILE);
exit(0);

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--
Bruce Momjian <bruce@momjian.us> http://momjian.us
EnterpriseDB http://postgres.enterprisedb.com

+ If your life is a hard drive, Christ can be your backup. +

Patch applied. Thanks.
--
Tatsuo Ishii
SRA OSS, Inc. Japan