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From jmmec <jmmec2...@gmail.com>
Subject ZK 3.4.5: Very Strange Write Latency Problem?
Date Fri, 21 Feb 2014 01:44:48 GMT
Hi everyone,

I'm new to the list and especially ZooKeeper.  I'm exploring ZK 3.4.5 with
a dummy application (hacked up & simple) that is using the C API with async
calls.   It creates 100,000 znodes, slowly, where each znode has 133 bytes
of data.  Simple.  :)

Although my tool creates znodes slowly (about 84 per second) and CPU / RAM
/ Network / etc is not at all stressed, I am seeing periodically very long
"write" latency times (76ms+) reported by ZooKeeper.  My independent
analysis confirms what ZooKeeper is reporting.  Wow.

The one-page PDF file below explains the problem in more detail and
includes a chart that shows the periodic write latency delays:

https://docs.google.com/file/d/0Bww02z29xbYyUFEtbXQzOG9GVDA/edit?usp=sharing&pli=1

I don't know much about JAVA and haven't started poking into ZooKeeper, but
since ZooKeeper is reporting the latency, then it seems to be coming from
ZooKeeper itself.

Any idea what might be causing this, or how better to diagnose what might
be happening?

Thanks so much!

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