I am running a series of standard commercial benchmarks against
PostgreSQL under CYGWIN.
I start out connecting 1 user, then 10, 20, 30, 40, 50, etc until I get
to 100.
Everything is fine until I get to 40 to 50 users. At some point during
this benchmark, the backend processes seem to get out of sync with the
clients.
I use a commercial product called Benchmark Factory. We have used this
product to benchmark PostgreSQL, Oracle, MySQL, and SQL Server. It
connects to the database via ODBC. I know from a year's worth of
experience that the problem is not inside of the Benchmark Factory. This
is what I have observed.
When the number of clients get to about 50 plus or minus a few, the
benchmark runs, but when it starts to wind down, the backends are still
processing, seem to be waiting for some response from the backend that
never comes. I left it go last night and after 12 hours, the benchmark
still had not finish winding down. It normaly takes about 9 min to start
up a cycle, run the benchmark, and wind down.
I did a netstat -a on the server box and got about 50 ports that their
status was ESTABLISHED. When I did the netstat -a on the client box, I
got 50 ports that had a status of ESTABLISHED, but also got 50 ports that
were LISTENING. The client software seems to be waiting on messages from
the backend that never comes. Or maybe the message was sent, but got
lost.
I don't know how to describe the problem any better. Does someone have
any ideas how I might provide some better info?
BTW, Up through 40 users, PostgreSQL under CYGWIN using the TPC-C
benchmark performed very much the same as Linux PostgreSQL on the exact
hardware.
Thanks
Terry Carlin
VP Q/A
Great Bridge