On Wed, Sep 08, 2010 at 03:27:34PM -0400, Greg Smith wrote: - Tom Lane wrote: - >As of the 9.0 release, it's possible to run pgbench in a "multi thread" - >mode, and if you forced the subprocess rather than thread model it looks - >like the select() limit would be per subprocess rather than global. - >So I think you could get above the FD_SETSIZE limit with a bit of - >hacking if you were using 9.0's pgbench. No chance with 8.3 though. - > - - I believe David can do this easily enough by compiling a 9.0 source code - tree with the "--disable-thread-safety" option. That's the simplest way - to force the pgbench client to build itself using the multi-process - model, rather than the multi-threaded one. - - It's kind of futile to run pgbench simulating much more than a hundred - or two clients before 9.0 anyway. Without multiple workers, you're - likely to just run into the process switching limitations within pgbench - itself rather than testing server performance usefully. I've watched - the older pgbench program fail to come close to saturating an 8 core - server without running into its own limitations first. - - You might run a 9.0 pgbench client against an 8.3 server though, if you - did the whole thing starting from pgbench database initialization over - again--the built-in tables like "accounts" changed to "pgbench_accounts" - in 8.4. That might work, can't recall any changes that would prevent - it; but as I haven't tested it yet I can't say for sure. Thanks, I compiled the 9.0 RC1 branch with the --disable-thread-safety option and ran PG bench on my 8.3 DB it seemed to work fine, However, MAXCLIENTS is still 1024, if i hack it to switch it up to 2048 i get this: starting vacuum...end. select failed: Bad file descriptor <--------------- transaction type: TPC-B (sort of) scaling factor: 1 query mode: simple number of clients: 1900 number of threads: 1 number of transactions per client: 10 number of transactions actually processed: 3723/19000 tps = 52.007642 (including connections establishing) tps = 82.579077 (excluding connections establishing) I'm not sure what Tom is referring to with the select(2) limitation, maybe I'm running into it (where do i find that? /usr/include/sys/select.h? ) should i be running pgbench differently? I tried increasing the # of threads but that didn't increase the number of backend's and i'm trying to simulate 2000 physical backend processes. thanks Dave -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
