Michael, thank you for you reply. Question: if my web request fails to return a response, hence request method doesn't exit gracefully, could that perhaps cause a connection not to be returned to a connection pool? Reason I ask this is that if my thinking is right, I might have a clue to exactly where my problem is.
Regards, -Alen On Sep 19, 4:44 pm, Michael Bayer <[EMAIL PROTECTED]> wrote: > On Sep 19, 2008, at 10:05 AM, Alen Ribic wrote: > > > > > > > Good day. > > > I tried to perform a load test on my python web app using sqlalchemy > > as follows: > > 1000 requests > > 20 concurrent connections > > > Towards the end, I started getting an error from sqlalchemy module: > > TimeoutError: QueuePool limit of size 40 overflow 10 reached, > > connection timed out, timeout 30 > > > I'm not a load testing expert neither am I a sqlalchemy expert, but I > > thought that perhaps 20 concurrent connections would be comfortably > > handled by 40 pooled connections (+ the 10 overflowed) even if there > > are 1000 requests. Does this mean that the connections are not being > > returned to the pool quick enough? > > If you have connections timing out after 30 seconds, then one or more > of your requests is simply not returning. I would look into the > possibility of a deadlock, which is something that would eventually > time out all connections, or some other reason that connections are > being held opened persistently (such as, if they were being placed in > a collection somewhere that isn't cleared out). Normally, > connections are returned when they are closed or dereferenced, more > often the former, so there is not much of an "asynchronous" element to > the return of connections. If work couldn't be completed fast enough, > the req/sec would go down but the pool would not overflow, as long as > the concurrency entering the application is set to be lower than the > pool available (which in this case it is). --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "sqlalchemy" group. To post to this group, send email to sqlalchemy@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sqlalchemy?hl=en -~----------~----~----~----~------~----~------~--~---
