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From Jay Kreps <jay.kr...@gmail.com>
Subject Re: Increased CPU usage with 0.8.2-beta
Date Mon, 02 Feb 2015 17:48:49 GMT
Looking at that profile:

Misc. blocking socket activity, not actual CPU work:
   1  5.24%  5.24%   67781 300447 java.net.PlainSocketImpl.socketAccept
   2  5.24% 10.49%   67775 300515 java.net.PlainSocketImpl.socketAccept
   3  5.24% 15.73%   67773 300567 java.net.PlainSocketImpl.socketAccept
   4  5.24% 20.97%   67683 301396 sun.nio.ch.ServerSocketChannelImpl.accept0
   5  5.23% 26.20%   67582 301395 sun.nio.ch.EPollArrayWrapper.epollWait
   6  5.23% 31.42%   67529 301519 sun.nio.ch.EPollArrayWrapper.epollWait
   7  5.13% 36.55%   66297 302447 sun.nio.ch.EPollArrayWrapper.epollWait
   8  3.95% 40.51%   51071 302446 sun.nio.ch.EPollArrayWrapper.epollWait
   9  3.65% 44.16%   47234 303479 sun.nio.ch.EPollArrayWrapper.epollWait
  10  3.64% 47.80%   47019 302444 sun.nio.ch.EPollArrayWrapper.epollWait
  11  3.62% 51.42%   46768 302445 sun.nio.ch.EPollArrayWrapper.epollWait
  12  3.27% 54.69%   42237 303475 sun.nio.ch.EPollArrayWrapper.epollWait
  13  3.16% 57.85%   40892 303476 sun.nio.ch.EPollArrayWrapper.epollWait
  14  3.14% 60.99%   40556 303478 sun.nio.ch.EPollArrayWrapper.epollWait
  15  3.05% 64.04%   39428 303480 sun.nio.ch.EPollArrayWrapper.epollWait
  16  2.68% 66.72%   34673 303477 sun.nio.ch.EPollArrayWrapper.epollWait
  17  1.23% 67.95%   15867 303520 sun.nio.ch.EPollArrayWrapper.epollWait
  18  0.98% 68.93%   12663 303541 sun.nio.ch.EPollArrayWrapper.epollWait
  19  0.92% 69.85%   11920 303536 sun.nio.ch.EPollArrayWrapper.epollWait
  20  0.85% 70.70%   11015 303546 sun.nio.ch.EPollArrayWrapper.epollWait
  21  0.82% 71.53%   10625 303534 sun.nio.ch.EPollArrayWrapper.epollWait
  22  0.69% 72.21%    8866 303512 sun.nio.ch.EPollArrayWrapper.epollWait

  TransferTo to write data to socket, not actual CPU work (mostly)
  23  0.36% 72.57%    4592 304991 sun.nio.ch.FileDispatcherImpl.write0
  24  0.36% 72.92%    4589 305021 sun.nio.ch.FileDispatcherImpl.write0
  25  0.35% 73.27%    4503 304992 sun.nio.ch.FileDispatcherImpl.write0
  26  0.32% 73.60%    4198 305022 sun.nio.ch.FileDispatcherImpl.write0
  27  0.25% 73.85%    3250 305246 sun.nio.ch.FileDispatcherImpl.write0
  28  0.25% 74.10%    3249 305497 sun.nio.ch.FileDispatcherImpl.write0

  Request channel - Actual CPU
  29  0.22% 74.32%    2862 305000 sun.misc.Unsafe.unpark
  30  0.17% 74.49%    2163 304838 sun.misc.Unsafe.unpark
  31  0.14% 74.63%    1795 305240 sun.misc.Unsafe.unpark

  Purgatory - Actual CPU
  32  0.12% 74.75%    1553 305137 scala.collection.immutable.HashMap.$plus
  33  0.12% 74.87%    1546 305100 java.util.concurrent.ConcurrentHashMap.get
  34  0.12% 74.98%    1531 305181 java.util.concurrent.ConcurrentHashMap.get
  35  0.12% 75.10%    1526 305234 scala.collection.immutable.HashMap.$plus
  36  0.12% 75.22%    1521 305401 scala.collection.immutable.HashMap.$plus
  37  0.12% 75.34%    1519 305186 java.util.concurrent.ConcurrentHashMap.get
  38  0.12% 75.46%    1517 305264 java.util.concurrent.ConcurrentHashMap.get
  39  0.12% 75.57%    1514 305271 java.util.concurrent.ConcurrentHashMap.get
  40  0.12% 75.69%    1511 305250 scala.collection.immutable.HashMap.$plus
  41  0.12% 75.81%    1499 305155 java.util.concurrent.ConcurrentHashMap.get
  42  0.12% 75.92%    1496 305113 scala.collection.immutable.HashMap.$plus
  43  0.12% 76.04%    1496 305263 scala.collection.immutable.HashMap.$plus
  44  0.11% 76.15%    1480 305235 scala.collection.immutable.HashMap.$plus
  45  0.11% 76.26%    1444 305185 scala.collection.immutable.HashMap.$plus
  46  0.11% 76.37%    1428 305102 java.util.concurrent.ConcurrentHashMap.get
  47  0.11% 76.48%    1418 305320 java.util.concurrent.ConcurrentHashMap.get

  Compression - Actual CPU
  48  0.09% 76.58%    1187 306546 org.xerial.snappy.SnappyNative.rawCompress
  49  0.09% 76.67%    1174 305584 org.xerial.snappy.SnappyNative.rawCompress
  50  0.09% 76.76%    1173 305545 org.xerial.snappy.SnappyNative.rawCompress
  51  0.09% 76.85%    1165 305661 org.xerial.snappy.SnappyNative.rawCompress
  52  0.09% 76.94%    1152 307069 org.xerial.snappy.SnappyNative.rawCompress
  53  0.09% 77.02%    1121 305997 org.xerial.snappy.SnappyNative.rawCompress
  54  0.09% 77.11%    1117 307035 org.xerial.snappy.SnappyNative.rawCompress
  55  0.09% 77.19%    1106 306190 org.xerial.snappy.SnappyNative.rawCompress

On Mon, Feb 2, 2015 at 9:39 AM, Jay Kreps <jay.kreps@gmail.com> wrote:

> Ah, yeah, you're right. That is just wait time not CPU time. We should
> check that profile it must be something else on the list.
>
> -Jay
>
> On Mon, Feb 2, 2015 at 9:33 AM, Jun Rao <jun@confluent.io> wrote:
>
>> Hi, Mathias,
>>
>> From the hprof output, it seems that the top CPU consumers are
>> socketAccept() and epollWait(). As far as I am aware, there hasn't been
>> any
>> significant changes in the socket server code btw 0.8.1 and 0.8.2. Could
>> you run the same hprof test on 0.8.1 so that we can see the difference?
>>
>> Jaikiran,
>>
>> The fix you provided in probably unnecessary. The channel that we use in
>> SimpleConsumer (BlockingChannel) is configured to be blocking. So even
>> though the read from the socket is in a loop, each read blocks if there is
>> no bytes received from the broker. So, that shouldn't cause extra CPU
>> consumption.
>>
>> Thanks,
>>
>> Jun
>>
>> On Mon, Jan 26, 2015 at 10:05 AM, Mathias Söderberg <
>> mathias.soederberg@gmail.com> wrote:
>>
>> > Hi Neha,
>> >
>> > I sent an e-mail earlier today, but noticed now that it didn't actually
>> go
>> > through.
>> >
>> > Anyhow, I've attached two files, one with output from a 10 minute run
>> and
>> > one with output from a 30 minute run. Realized that maybe I should've
>> done
>> > one or two runs with 0.8.1.1 as well, but nevertheless.
>> >
>> > I upgraded our staging cluster to 0.8.2.0-rc2, and I'm seeing the same
>> CPU
>> > usage as with the beta version (basically pegging all cores). If I
>> manage
>> > to find the time I'll do another run with hprof on the rc2 version later
>> > today.
>> >
>> > Best regards,
>> > Mathias
>> >
>> > On Tue Dec 09 2014 at 10:08:21 PM Neha Narkhede <neha@confluent.io>
>> wrote:
>> >
>> >> The following should be sufficient
>> >>
>> >> java
>> >> -agentlib:hprof=cpu=samples,depth=100,interval=20,lineno=
>> >> y,thread=y,file=kafka.hprof
>> >> <classname>
>> >>
>> >> You would need to start the Kafka server with the settings above for
>> >> sometime until you observe the problem.
>> >>
>> >> On Tue, Dec 9, 2014 at 3:47 AM, Mathias Söderberg <
>> >> mathias.soederberg@gmail.com> wrote:
>> >>
>> >> > Hi Neha,
>> >> >
>> >> > Yeah sure. I'm not familiar with hprof, so any particular options I
>> >> should
>> >> > include or just run with defaults?
>> >> >
>> >> > Best regards,
>> >> > Mathias
>> >> >
>> >> > On Mon Dec 08 2014 at 7:41:32 PM Neha Narkhede <neha@confluent.io>
>> >> wrote:
>> >> >
>> >> > > Thanks for reporting the issue. Would you mind running hprof and
>> >> sending
>> >> > > the output?
>> >> > >
>> >> > > On Mon, Dec 8, 2014 at 1:25 AM, Mathias Söderberg <
>> >> > > mathias.soederberg@gmail.com> wrote:
>> >> > >
>> >> > > > Good day,
>> >> > > >
>> >> > > > I upgraded a Kafka cluster from v0.8.1.1 to v0.8.2-beta and
>> noticed
>> >> > that
>> >> > > > the CPU usage on the broker machines went up by roughly 40%,
from
>> >> ~60%
>> >> > to
>> >> > > > ~100% and am wondering if anyone else has experienced something
>> >> > similar?
>> >> > > > The load average also went up by 2x-3x.
>> >> > > >
>> >> > > > We're running on EC2 and the cluster currently consists of
four
>> >> > > m1.xlarge,
>> >> > > > with roughly 1100 topics / 4000 partitions. Using Java 7
>> (1.7.0_65
>> >> to
>> >> > be
>> >> > > > exact) and Scala 2.9.2. Configurations can be found over
here:
>> >> > > > https://gist.github.com/mthssdrbrg/7df34a795e07eef10262.
>> >> > > >
>> >> > > > I'm assuming that this is not expected behaviour for 0.8.2-beta?
>> >> > > >
>> >> > > > Best regards,
>> >> > > > Mathias
>> >> > > >
>> >> > >
>> >> > >
>> >> > >
>> >> > > --
>> >> > > Thanks,
>> >> > > Neha
>> >> > >
>> >> >
>> >>
>> >>
>> >>
>> >> --
>> >> Thanks,
>> >> Neha
>> >>
>> >
>>
>
>

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