> I think that the degree of parallelism to consider is nclients, not > nthreads: while connection time is accumulated in conn_time, other > clients are possibly doing their transactions, in parallel,
I'm not sure about this. I think pgbench will not start transactions until all clients establish connections to PostgreSQL. I found this while playing with pgpool-II. pgpool-II pre-forks child process, whose number is defined by "num_init_children" directive. What I observed was, pgbench starts connecting to pgpool-II until "-c" connections are established. So, if "-c" is larger than "num_init_children", no transaction starts. > even if it > is in the same thread, so it is not "stopped time" for all clients. It > starts to matter with "-j 1 -c 30" and slow transactions, the > cumulated conn_time in each thread may be arbitrary close to the whole > time if there are many clients. > > Now, I do not think that this tps computation makes that much > sense. If you want to know the tps without reconnect, run without > reconnecting... It is clear that I do not get this figure when running > without -C, so maybe > the tps with/without reconnection should be dropped? > > Anyway, here is a patch, which: > - fixes the "exclude" computation (s/nthreads/nclients/) > - fixes the count total for skipped (s/threads/thread/) > - removes a useless parameter to doCustom > (the conn_time is available through the thread parameter). I have tested your patch. It seems the tolerance is much better than before with your patch. With the patch: ./pgbench -C -n -p 11002 -c 10 -T 30 -f test.sql test transaction type: Custom query scaling factor: 1 query mode: simple number of clients: 10 number of threads: 1 duration: 30 s number of transactions actually processed: 2887 latency average: 103.914 ms tps = 95.896850 (including connections establishing) tps = 98.101662 (excluding connections establishing) Without the patch: ./pgbench -C -n -p 11002 -c 10 -T 30 -f test.sql test transaction type: Custom query scaling factor: 1 query mode: simple number of clients: 10 number of threads: 1 duration: 30 s number of transactions actually processed: 2887 latency average: 103.914 ms tps = 95.919415 (including connections establishing) tps = 124.732475 (excluding connections establishing) I'm going to commit your patch if there's no objection. Best regards, -- Tatsuo Ishii SRA OSS, Inc. Japan English: http://www.sraoss.co.jp/index_en.php Japanese:http://www.sraoss.co.jp -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
