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From Allen Wang <aw...@netflix.com.INVALID>
Subject Re: High CPU usage of Crc32 on Kafka broker
Date Thu, 06 Nov 2014 22:36:35 GMT
Sure. Here is the link to the screen shot of jmc with the JTR file loaded:

http://picpaste.com/fligh-recorder-crc.png



On Thu, Nov 6, 2014 at 2:12 PM, Neha Narkhede <neha.narkhede@gmail.com>
wrote:

> Allen,
>
> Apache mailing lists don't allow attachments. Could you please link to a
> pastebin or something?
>
> Thanks,
> Neha
>
> On Thu, Nov 6, 2014 at 12:02 PM, Allen Wang <awang@netflix.com.invalid>
> wrote:
>
> > After digging more into the stack trace got from flight recorder (which
> is
> > attached), it seems that Kafka (0.8.1.1) can optimize the usage of Crc32.
> > The stack trace shows that Crc32 is invoked twice from Log.append().
> First
> > is from the line number 231:
> >
> > val appendInfo = analyzeAndValidateMessageSet(messages)
> >
> > The second time is from line 252 in the same function:
> >
> > validMessages = validMessages.assignOffsets(offset, appendInfo.codec)
> >
> > If one of the Crc32 invocation can be eliminated, we are looking at
> saving
> > at least 7% of CPU usage.
> >
> > Thanks,
> > Allen
> >
> >
> >
> >
> > On Wed, Nov 5, 2014 at 6:32 PM, Allen Wang <awang@netflix.com> wrote:
> >
> >> Hi,
> >>
> >> Using flight recorder, we have observed high CPU usage of CRC32
> >> (kafka.utils.Crc32.update()) on Kafka broker. It uses as much as 25% of
> CPU
> >> on an instance. Tracking down stack trace, this method is invoked by
> >> ReplicaFetcherThread.
> >>
> >> Is there any tuning we can do to reduce this?
> >>
> >> Also on the topic of CPU utilization, we observed that overall CPU
> >> utilization is proportional to AllTopicsBytesInPerSec metric. Does this
> >> metric include incoming replication traffic?
> >>
> >> Thanks,
> >> Allen
> >>
> >>
> >
>

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