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From Ran Tavory <ran...@gmail.com>
Subject Re: performance tuning - where does the slowness come from?
Date Tue, 04 May 2010 18:57:41 GMT
I canceled mmap and indeed memory usage is sane again. So far performance
hasn't been great, but I'll wait and see.

I'm also interested in a way to cap mmap so I can take advantage of it but
not swap the host to death...

On Tue, May 4, 2010 at 9:38 PM, Kyusik Chung <kyusik@discovereads.com>wrote:

> This sounds just like the slowness I was asking about in another thread -
> after a lot of reads, the machine uses up all available memory on the box
> and then starts swapping.
>
> My understanding was that mmap helps greatly with read and write perf
> (until the box starts swapping I guess)...is there any way to use mmap and
> cap how much memory it takes up?
>
> What do people use in production?  mmap or no mmap?
>
> Thanks!
>
> Kyusik Chung
>
> On May 4, 2010, at 10:11 AM, Schubert Zhang wrote:
>
> 1. When initially startup your nodes, please plan your InitialToken of each
> node evenly.
> 2. <DiskAccessMode>standard</DiskAccessMode>
>
> On Tue, May 4, 2010 at 9:09 PM, Boris Shulman <shulmanb@gmail.com> wrote:
>
>> I think that the extra (more than 4GB) memory usage comes from the
>> mmaped io, that is why it happens only for reads.
>>
>> On Tue, May 4, 2010 at 2:02 PM, Jordan Pittier <jordan.pittier@gmail.com>
>> wrote:
>> > I'm facing the same issue with swap. It only occurs when I perform read
>> > operations (write are very fast :)). So I can't help you with the memory
>> > probleme.
>> >
>> > But to balance the load evenly between nodes in cluster just manually
>> fix
>> > their token.(the "formula" is i * 2^127 / nb_nodes).
>> >
>> > Jordzn
>> >
>> > On Tue, May 4, 2010 at 8:20 AM, Ran Tavory <rantav@gmail.com> wrote:
>> >>
>> >> I'm looking into performance issues on a 0.6.1 cluster. I see two
>> >> symptoms:
>> >> 1. Reads and writes are slow
>> >> 2. One of the hosts is doing a lot of GC.
>> >> 1 is slow in the sense that in normal state the cluster used to make
>> >> around 3-5k read and writes per second (6-10k operations per second),
>> but
>> >> how it's in the order of 200-400 ops per second, sometimes even less.
>> >> 2 looks like this:
>> >> $ tail -f /outbrain/cassandra/log/system.log
>> >>  INFO [GC inspection] 2010-05-04 00:42:18,636 GCInspector.java (line
>> 110)
>> >> GC for ParNew: 672 ms, 166482384 reclaimed leaving 2872087208 used; max
>> is
>> >> 4432068608
>> >>  INFO [GC inspection] 2010-05-04 00:42:28,638 GCInspector.java (line
>> 110)
>> >> GC for ParNew: 498 ms, 166493352 reclaimed leaving 2836049448 used; max
>> is
>> >> 4432068608
>> >>  INFO [GC inspection] 2010-05-04 00:42:38,640 GCInspector.java (line
>> 110)
>> >> GC for ParNew: 327 ms, 166091528 reclaimed leaving 2796888424 used; max
>> is
>> >> 4432068608
>> >> ... and it goes on and on for hours, no stopping...
>> >> The cluster is made of 6 hosts, 3 in one DC and 3 in another.
>> >> Each host has 8G RAM.
>> >> -Xmx=4G
>> >> For some reason, the load isn't distributed evenly b/w the hosts,
>> although
>> >> I'm not sure this is the cause for slowness
>> >> $ nodetool -h localhost -p 9004 ring
>> >> Address       Status     Load          Range
>> >>        Ring
>> >>
>> >> 144413773383729447702215082383444206680
>> >> 192.168.252.99Up         15.94 GB
>> >>  66002764663998929243644931915471302076     |<--|
>> >> 192.168.254.57Up         19.84 GB
>> >>  81288739225600737067856268063987022738     |   ^
>> >> 192.168.254.58Up         973.78 MB
>> >> 86999744104066390588161689990810839743     v   |
>> >> 192.168.252.62Up         5.18 GB
>> >> 88308919879653155454332084719458267849     |   ^
>> >> 192.168.254.59Up         10.57 GB
>> >>  142482163220375328195837946953175033937    v   |
>> >> 192.168.252.61Up         11.36 GB
>> >>  144413773383729447702215082383444206680    |-->|
>> >> The slow host is 192.168.252.61 and it isn't the most loaded one.
>> >> The host is waiting a lot on IO and the load average is usually 6-7
>> >> $ w
>> >>  00:42:56 up 11 days, 13:22,  1 user,  load average: 6.21, 5.52, 3.93
>> >> $ vmstat 5
>> >> procs -----------memory---------- ---swap-- -----io---- --system--
>> >> -----cpu------
>> >>  r  b   swpd   free   buff  cache   si   so    bi    bo   in   cs us sy
>> id
>> >> wa st
>> >>  0  8 2147844  45744   1816 4457384    6    5    66    32    5    2  1
>>  1
>> >> 96  2  0
>> >>  0  8 2147164  49020   1808 4451596  385    0  2345    58 3372 9957  2
>>  2
>> >> 78 18  0
>> >>  0  3 2146432  45704   1812 4453956  342    0  2274   108 3937 10732  2
>>  2
>> >> 78 19  0
>> >>  0  1 2146252  44696   1804 4453436  345  164  1939   294 3647 7833  2
>>  2
>> >> 78 18  0
>> >>  0  1 2145960  46924   1744 4451260  158    0  2423   122 4354 14597  2
>>  2
>> >> 77 18  0
>> >>  7  1 2138344  44676    952 4504148 1722  403  1722   406 1388  439 87
>>  0
>> >> 10  2  0
>> >>  7  2 2137248  45652    956 4499436 1384  655  1384   658 1356  392 87
>>  0
>> >> 10  3  0
>> >>  7  1 2135976  46764    956 4495020 1366  718  1366   718 1395  380 87
>>  0
>> >>  9  4  0
>> >>  0  8 2134484  46964    956 4489420 1673  555  1814   586 1601 215590
>> 14
>> >>  2 68 16  0
>> >>  0  1 2135388  47444    972 4488516  785  833  2390   995 3812 8305  2
>>  2
>> >> 77 20  0
>> >>  0 10 2135164  45928    980 4488796  788  543  2275   626 36
>> >> So, the host is swapping like crazy...
>> >> top shows that it's using a lot of memory. As noted before -Xmx=4G and
>> >> nothing else seems to be using a lot of memory on the host except for
>> the
>> >> cassandra process, however, of the 8G ram on the host, 92% is used by
>> >> cassandra. How's that?
>> >> Top shows there's 3.9g Shared and 7.2g Resident and 15.9g Virtual. Why
>> >> does it have 15g virtual? And why 7.2 RES? This can explain the
>> slowness in
>> >> swapping.
>> >> $ top
>> >>   PID USER      PR  NI  VIRT  RES  SHR S %CPU %MEM    TIME+  COMMAND
>> >>
>> >>
>> >> 20281 cassandr  25   0 15.9g 7.2g 3.9g S 33.3 92.6 175:30.27 java
>> >> So, can the total memory be controlled?
>> >> Or perhaps I'm looking in the wrong direction...
>> >> I've looked at all the cassandra JMX counts and nothing seemed
>> suspicious
>> >> so far. By suspicious i mean a large number of pending tasks - there
>> were
>> >> always very small numbers in each pool.
>> >> About read and write latencies, I'm not sure what the normal state is,
>> but
>> >> here's an example of what I see on the problematic host:
>> >> #mbean = org.apache.cassandra.service:type=StorageProxy:
>> >> RecentReadLatencyMicros = 30105.888180684495;
>> >> TotalReadLatencyMicros = 78543052801;
>> >> TotalWriteLatencyMicros = 4213118609;
>> >> RecentWriteLatencyMicros = 1444.4809201925639;
>> >> ReadOperations = 4779553;
>> >> RangeOperations = 0;
>> >> TotalRangeLatencyMicros = 0;
>> >> RecentRangeLatencyMicros = NaN;
>> >> WriteOperations = 4740093;
>> >> And the only pool that I do see some pending tasks is the
>> ROW-READ-STAGE,
>> >> but it doesn't look like much, usually around 6-8:
>> >> #mbean = org.apache.cassandra.concurrent:type=ROW-READ-STAGE:
>> >> ActiveCount = 8;
>> >> PendingTasks = 8;
>> >> CompletedTasks = 5427955;
>> >> Any help finding the solution is appreciated, thanks...
>> >> Below are a few more JMXes I collected from the system that may be
>> >> interesting.
>> >> #mbean = java.lang:type=Memory:
>> >> Verbose = false;
>> >> HeapMemoryUsage = {
>> >>   committed = 3767279616;
>> >>   init = 134217728;
>> >>   max = 4293656576;
>> >>   used = 1237105080;
>> >>  };
>> >> NonHeapMemoryUsage = {
>> >>   committed = 35061760;
>> >>   init = 24313856;
>> >>   max = 138412032;
>> >>   used = 23151320;
>> >>  };
>> >> ObjectPendingFinalizationCount = 0;
>> >> #mbean = java.lang:name=ParNew,type=GarbageCollector:
>> >> LastGcInfo = {
>> >>   GcThreadCount = 11;
>> >>   duration = 136;
>> >>   endTime = 42219272;
>> >>   id = 11719;
>> >>   memoryUsageAfterGc = {
>> >>     ( CMS Perm Gen ) = {
>> >>       key = CMS Perm Gen;
>> >>       value = {
>> >>         committed = 29229056;
>> >>         init = 21757952;
>> >>         max = 88080384;
>> >>         used = 17648848;
>> >>        };
>> >>      };
>> >>     ( Code Cache ) = {
>> >>       key = Code Cache;
>> >>       value = {
>> >>         committed = 5832704;
>> >>         init = 2555904;
>> >>         max = 50331648;
>> >>         used = 5563520;
>> >>        };
>> >>      };
>> >>     ( CMS Old Gen ) = {
>> >>       key = CMS Old Gen;
>> >>       value = {
>> >>         committed = 3594133504;
>> >>         init = 112459776;
>> >>         max = 4120510464;
>> >>         used = 964565720;
>> >>        };
>> >>      };
>> >>     ( Par Eden Space ) = {
>> >>       key = Par Eden Space;
>> >>       value = {
>> >>         committed = 171835392;
>> >>         init = 21495808;
>> >>         max = 171835392;
>> >>         used = 0;
>> >>        };
>> >>      };
>> >>     ( Par Survivor Space ) = {
>> >>       key = Par Survivor Space;
>> >>       value = {
>> >>         committed = 1310720;
>> >>         init = 131072;
>> >>         max = 1310720;
>> >>         used = 0;
>> >>        };
>> >>      };
>> >>    };
>> >>   memoryUsageBeforeGc = {
>> >>     ( CMS Perm Gen ) = {
>> >>       key = CMS Perm Gen;
>> >>       value = {
>> >>         committed = 29229056;
>> >>         init = 21757952;
>> >>         max = 88080384;
>> >>         used = 17648848;
>> >>        };
>> >>      };
>> >>     ( Code Cache ) = {
>> >>       key = Code Cache;
>> >>       value = {
>> >>         committed = 5832704;
>> >>         init = 2555904;
>> >>         max = 50331648;
>> >>         used = 5563520;
>> >>        };
>> >>      };
>> >>     ( CMS Old Gen ) = {
>> >>       key = CMS Old Gen;
>> >>       value = {
>> >>         committed = 3594133504;
>> >>         init = 112459776;
>> >>         max = 4120510464;
>> >>         used = 959221872;
>> >>        };
>> >>      };
>> >>     ( Par Eden Space ) = {
>> >>       key = Par Eden Space;
>> >>       value = {
>> >>         committed = 171835392;
>> >>         init = 21495808;
>> >>         max = 171835392;
>> >>         used = 171835392;
>> >>        };
>> >>      };
>> >>     ( Par Survivor Space ) = {
>> >>       key = Par Survivor Space;
>> >>       value = {
>> >>         committed = 1310720;
>> >>         init = 131072;
>> >>         max = 1310720;
>> >>         used = 0;
>> >>        };
>> >>      };
>> >>    };
>> >>   startTime = 42219136;
>> >>  };
>> >> CollectionCount = 11720;
>> >> CollectionTime = 4561730;
>> >> Name = ParNew;
>> >> Valid = true;
>> >> MemoryPoolNames = [ Par Eden Space, Par Survivor Space ];
>> >> #mbean = java.lang:type=OperatingSystem:
>> >> MaxFileDescriptorCount = 63536;
>> >> OpenFileDescriptorCount = 75;
>> >> CommittedVirtualMemorySize = 17787711488;
>> >> FreePhysicalMemorySize = 45522944;
>> >> FreeSwapSpaceSize = 2123968512;
>> >> ProcessCpuTime = 12251460000000;
>> >> TotalPhysicalMemorySize = 8364417024;
>> >> TotalSwapSpaceSize = 4294959104;
>> >> Name = Linux;
>> >> AvailableProcessors = 8;
>> >> Arch = amd64;
>> >> SystemLoadAverage = 4.36;
>> >> Version = 2.6.18-164.15.1.el5;
>> >> #mbean = java.lang:type=Runtime:
>> >> Name = 20281@ob1061.nydc1.outbrain.com;
>> >>
>> >> ClassPath =
>> >>
>> /outbrain/cassandra/apache-cassandra-0.6.1/bin/../conf:/outbrain/cassandra/apache-cassandra-0.6.1/bin/../build/classes:/outbrain/cassandra/apache-cassandra-0.6.1/bin/..
>> >>
>> >>
>> /lib/antlr-3.1.3.jar:/outbrain/cassandra/apache-cassandra-0.6.1/bin/../lib/apache-cassandra-0.6.1.jar:/outbrain/cassandra/apache-cassandra-0.6.1/bin/../lib/avro-1.2.0-dev.jar:/outb
>> >>
>> >>
>> rain/cassandra/apache-cassandra-0.6.1/bin/../lib/clhm-production.jar:/outbrain/cassandra/apache-cassandra-0.6.1/bin/../lib/commons-cli-1.1.jar:/outbrain/cassandra/apache-cassandra-
>> >>
>> >>
>> 0.6.1/bin/../lib/commons-codec-1.2.jar:/outbrain/cassandra/apache-cassandra-0.6.1/bin/../lib/commons-collections-3.2.1.jar:/outbrain/cassandra/apache-cassandra-0.6.1/bin/../lib/com
>> >>
>> >>
>> mons-lang-2.4.jar:/outbrain/cassandra/apache-cassandra-0.6.1/bin/../lib/google-collections-1.0.jar:/outbrain/cassandra/apache-cassandra-0.6.1/bin/../lib/hadoop-core-0.20.1.jar:/out
>> >>
>> >>
>> brain/cassandra/apache-cassandra-0.6.1/bin/../lib/high-scale-lib.jar:/outbrain/cassandra/apache-cassandra-0.6.1/bin/../lib/ivy-2.1.0.jar:/outbrain/cassandra/apache-cassandra-0.6.1/
>> >>
>> >>
>> bin/../lib/jackson-core-asl-1.4.0.jar:/outbrain/cassandra/apache-cassandra-0.6.1/bin/../lib/jackson-mapper-asl-1.4.0.jar:/outbrain/cassandra/apache-cassandra-0.6.1/bin/../lib/jline
>> >>
>> >>
>> -0.9.94.jar:/outbrain/cassandra/apache-cassandra-0.6.1/bin/../lib/json-simple-1.1.jar:/outbrain/cassandra/apache-cassandra-0.6.1/bin/../lib/libthrift-r917130.jar:/outbrain/cassandr
>> >>
>> >>
>> a/apache-cassandra-0.6.1/bin/../lib/log4j-1.2.14.jar:/outbrain/cassandra/apache-cassandra-0.6.1/bin/../lib/slf4j-api-1.5.8.jar:/outbrain/cassandra/apache-cassandra-0.6.1/bin/../lib
>> >> /slf4j-log4j12-1.5.8.jar;
>> >>
>> >> BootClassPath =
>> >>
>> /usr/java/jdk1.6.0_17/jre/lib/alt-rt.jar:/usr/java/jdk1.6.0_17/jre/lib/resources.jar:/usr/java/jdk1.6.0_17/jre/lib/rt.jar:/usr/java/jdk1.6.0_17/jre/lib/sunrsasign.j
>> >>
>> >>
>> ar:/usr/java/jdk1.6.0_17/jre/lib/jsse.jar:/usr/java/jdk1.6.0_17/jre/lib/jce.jar:/usr/java/jdk1.6.0_17/jre/lib/charsets.jar:/usr/java/jdk1.6.0_17/jre/classes;
>> >>
>> >> LibraryPath =
>> >>
>> /usr/java/jdk1.6.0_17/jre/lib/amd64/server:/usr/java/jdk1.6.0_17/jre/lib/amd64:/usr/java/jdk1.6.0_17/jre/../lib/amd64:/usr/java/packages/lib/amd64:/lib:/usr/lib;
>> >>
>> >> VmName = Java HotSpot(TM) 64-Bit Server VM;
>> >>
>> >> VmVendor = Sun Microsystems Inc.;
>> >>
>> >> VmVersion = 14.3-b01;
>> >>
>> >> BootClassPathSupported = true;
>> >>
>> >> InputArguments = [ -ea, -Xms128M, -Xmx4G, -XX:TargetSurvivorRatio=90,
>> >> -XX:+AggressiveOpts, -XX:+UseParNewGC, -XX:+UseConcMarkSweepGC,
>> >> -XX:+CMSParallelRemarkEnabled, -XX:+HeapDumpOnOutOfMemoryError,
>> >> -XX:SurvivorRatio=128, -XX:MaxTenuringThreshold=0,
>> >> -Dcom.sun.management.jmxremote.port=9004,
>> >> -Dcom.sun.management.jmxremote.ssl=false,
>> >> -Dcom.sun.management.jmxremote.authenticate=false,
>> >>
>> -Dstorage-config=/outbrain/cassandra/apache-cassandra-0.6.1/bin/../conf,
>> >> -Dcassandra-pidfile=/var/run/cassandra.pid ];
>> >>
>> >> ManagementSpecVersion = 1.2;
>> >>
>> >> SpecName = Java Virtual Machine Specification;
>> >>
>> >> SpecVendor = Sun Microsystems Inc.;
>> >>
>> >> SpecVersion = 1.0;
>> >>
>> >> StartTime = 1272911001415;
>> >> ...
>> >
>>
>
>
>

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