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| author | Andres Freund <andres@anarazel.de> | 2021-08-04 19:19:44 -0700 |
|---|---|---|
| committer | Andres Freund <andres@anarazel.de> | 2021-08-04 19:19:58 -0700 |
| commit | fa604e0dd07a39ba34f93d06ded8243280dffdeb (patch) | |
| tree | 63dcc3400102dc8ffa744276c2c6278341274065 /src | |
| parent | e8086bd3ba0ab73a18ac2293dd14f488734126ec (diff) | |
| download | postgresql-fa604e0dd07a39ba34f93d06ded8243280dffdeb.tar.gz postgresql-fa604e0dd07a39ba34f93d06ded8243280dffdeb.zip | |
pgbench: When using pipelining only do PQconsumeInput() when necessary.
Up to now we did a PQconsumeInput() for each pipelined query, asking the OS
for more input - which it often won't have, as all results might already have
been sent. That turns out to have a noticeable performance impact.
Alvaro Herrera reviewed the idea to add the PQisBusy() check, but not this
concrete patch.
Author: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/20210720180039.23rivhdft3l4mayn@alap3.anarazel.de
Backpatch: 14, where libpq/pgbench pipelining was introduced.
Diffstat (limited to 'src')
| -rw-r--r-- | src/bin/pgbench/pgbench.c | 9 |
1 files changed, 8 insertions, 1 deletions
diff --git a/src/bin/pgbench/pgbench.c b/src/bin/pgbench/pgbench.c index 364b5a2e47d..129cf2ed61d 100644 --- a/src/bin/pgbench/pgbench.c +++ b/src/bin/pgbench/pgbench.c @@ -3460,7 +3460,14 @@ advanceConnectionState(TState *thread, CState *st, StatsData *agg) */ case CSTATE_WAIT_RESULT: pg_log_debug("client %d receiving", st->id); - if (!PQconsumeInput(st->con)) + + /* + * Only check for new network data if we processed all data + * fetched prior. Otherwise we end up doing a syscall for each + * individual pipelined query, which has a measurable + * performance impact. + */ + if (PQisBusy(st->con) && !PQconsumeInput(st->con)) { /* there's something wrong */ commandFailed(st, "SQL", "perhaps the backend died while processing"); |