I'm not very experienced personally with running zk on ec2 smalls, Ted usually has the ec2 related insight. Given these boxes are not loaded or lightly loaded, and you've ruled out gc/swap, the only thing I can think of is that something is going on under the covers at the vm level that's causing the high latency you're seeing.

You're seeing 15 _minutes_ max latency. I can't think of what would cause that inside zk. Any chance that the VM is shutting down or "freezing" during that period? I dont' know. Are you monitoring that system from a second system? Perhaps that might shed some light (monitor the cpu/disk activity using some monitoring tool like ganglia, nagios, etc... or even more primitive, perhaps doing a ping to that system and tracking the round trip time/packet loss, dump to a file and review the next day, etc...)


On 06/15/2010 03:59 PM, Jordan Zimmerman wrote:
They're small instances. The thing is that these machines are doing
next to no work. We're just running simple little tests. The session
expiration has not happened while I've been watching. It tends to
happen over night.


On Jun 15, 2010, at 1:50 PM, Ted Dunning wrote:

As usual, the ZK team provides the best feedback.

I would be bold enough to ask what kind of ec2 instances you are
running on.  Small instances are small chunks of larger machines
and are sometimes subject to competition for resources from the
other tenants.

On Tue, Jun 15, 2010 at 12:30 PM, Patrick Hunt<ph...@apache.org>
wrote: 3) under-provisioned virtual machines (ie vmware)


Given that you've ruled out the gc (most common), disk utilization
would be the next thing to check.

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