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From Keith Turner <>
Subject Re: hdfs cpu usage
Date Sat, 07 Feb 2015 15:50:45 GMT
Is this happening on just one node, or all nodes?  Have you run w/o problem
on google cloud env before?  Do you see the problem if you restart the vms?

On Fri, Feb 6, 2015 at 9:34 PM, Ara Ebrahimi <>

> Hi,
> We’re seeing some weird behavior from the hdfs daemon on google cloud
> environment when we use accumulo Scanner to sequentially scan a table. Top
> reports 200-300% cpu usage for the hdfs daemon. Accumulo is also around
> 500%. iostat %util is low. avgrq-sz is low, rMB/s is low, there’s lots of
> free memory. It seems like something causes the hdfs daemon to consume a
> lot of cpu and not to send enough read requests to the disk (ssd actually,
> so disk is super fast and vastly under-utilized). The process which sends
> scan requests to accumulo is 500% active (using 3 query batch threads and
> aggressive scan-batch-size/read-ahead-threashold values). So it seems like
> somehow hdfs is the bottleneck. On another cluster we rarely see hdfs
> daemon going over 10% cpu usage. Any idea what the issue could be?
> Thanks,
> Ara.
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