On Fri, 2014-06-20 at 12:40 +0100, Gordon Sim wrote: > On 06/19/2014 10:03 PM, smartdog wrote: > > I am not sending big messages, just a couple of words. Indeed, I use AMQP > > 1.0. Then it seems the static 1000ms latency comes from qpid timeout for > > waiting more messages to write to the store. Can I adjust the timeout value > > in qpid source code? I would be happy if we could reduce it to 100ms for > > durable messages. > > The timeout is 500ms by default (at least on trunk at present and I > doubt its changed very recently). To edit it change the value for > MessageStoreImpl::defJournalFlushTimeout in > cpp/src/qpid/legacystore/MessageStoreImpl.cpp > > (There is a timer task per journal, though at present configured to use > the same periodicity. So it would be possible without too much work to > make it configurable on a per queue basis if anyone had the inclination). >
That sounds like an unreasonably large default timeout. Even on cheap hardware network latency is a few milliseconds and I'm guessing disk latency is a lot less. A half-second timeout to batch messages from network to disk sounds completely out of line. Batching for high throughput is one thing, but imposing such a large artificial latency on low-throughput applications doesn't make sense. I would guess that a more appropriate timeout is in the milliseconds or sub-millisecond range (if it is really necessary at all) but it would require some performance measurements to determine that. Cheers, Alan. --------------------------------------------------------------------- To unsubscribe, e-mail: users-unsubscr...@qpid.apache.org For additional commands, e-mail: users-h...@qpid.apache.org