On Wed, 2009-08-12 at 08:56 -0400, Alan Conway wrote: > On 08/12/2009 07:25 AM, Gordon Sim wrote: > > The output from make check-long is now showing lots of warnings of the > > following form: > > > > soak-1: 2009-08-12 06:40:56 warning Timer woken up 3ms late > > > > Is this a serious issue? If so what do we need to do to prevent it > > happening? If not, is warning the appropriate logging level? > > > > > > I've also been seeing a lot of those messages since sometime last week. As it > stands its not a useful message at any log level so I'd be inclined to remove > it > or else build in some fudge factor so it only reports if the Timer is > significantly late. Hard to guess what's a good value for "significant".
I think that these messages are less important than the overrun messages, but useful in retrospect - to understand that a timing delay isn't the result of anything happening in qpidd, but caused by the machine being so busy (for whatever reason) that the kernel couldn't wake the timer thread up in time. If you are seeing lots and lots of these messages it almost certainly means that the io threads (or I guess another process entirely) are monopolising the cpus to the extent that the timing thread can't be restarted, and this is perhaps important in itself. Currently the notion of significant is 1ms for active Timer tasks and 500ms for cancelled timer tasks. The significance of a delay will strongly depend on what time dependent tasks are going on so it's difficult to know currently the heartbeat related tasks are the most time sensitive and they fail after delays of about 0.5 * the heartbeat interval. As it currently stands we could probably increase the limit to 50ms and not miss really significant delays. Thoughts? Andrew > --------------------------------------------------------------------- Apache Qpid - AMQP Messaging Implementation Project: http://qpid.apache.org Use/Interact: mailto:[email protected]
