Hello devs,
When \sleep is used within a pgbench script it resets txn_scheduled which
is used for computing stats about the transaction, resulting in absurd
statistics:
latency average = 0.649 ms *** ??? ***
...
script statistics:
- statement latencies in milliseconds:
0.235 BEGIN;
100.301 \sleep 100 ms
0.351 END;
I probably created this bug when adding "--rate" in 9.4 and trying to be
too clever. As nobody complained yet about it, I'm not sure it is worth
fixing it there, though.
The fix is that "\sleep" does not have to interfere with the txn_scheduled
field, see the attached patch.
latency average = 100.237 ms *** BETTER ***
...
script statistics:
- statement latencies in milliseconds:
0.099 BEGIN;
100.001 \sleep 100 ms
0.135 END;
--
Fabien.diff --git a/src/bin/pgbench/pgbench.c b/src/bin/pgbench/pgbench.c
index 8027955..de9b1b6 100644
--- a/src/bin/pgbench/pgbench.c
+++ b/src/bin/pgbench/pgbench.c
@@ -250,6 +250,7 @@ typedef struct
int nvariables; /* number of variables */
bool vars_sorted; /* are variables sorted by name? */
int64 txn_scheduled; /* scheduled start time of transaction (usec) */
+ int64 sleep_until; /* scheduled start time of next cmd (usec) */
instr_time txn_begin; /* used for measuring schedule lag times */
instr_time stmt_begin; /* used for measuring statement latencies */
int use_file; /* index in sql_scripts for this client */
@@ -1828,6 +1829,7 @@ top:
}
}
+ st->sleep_until = st->txn_scheduled;
st->sleeping = true;
st->throttling = true;
st->is_throttled = true;
@@ -1840,7 +1842,7 @@ top:
{ /* are we sleeping? */
if (INSTR_TIME_IS_ZERO(now))
INSTR_TIME_SET_CURRENT(now);
- if (INSTR_TIME_GET_MICROSEC(now) < st->txn_scheduled)
+ if (INSTR_TIME_GET_MICROSEC(now) < st->sleep_until)
return true; /* Still sleeping, nothing to do here */
/* Else done sleeping, go ahead with next command */
st->sleeping = false;
@@ -2139,7 +2141,7 @@ top:
usec *= 1000000;
INSTR_TIME_SET_CURRENT(now);
- st->txn_scheduled = INSTR_TIME_GET_MICROSEC(now) + usec;
+ st->sleep_until = INSTR_TIME_GET_MICROSEC(now) + usec;
st->sleeping = true;
st->listen = true;
--
Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers
