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From Jordan Pittier <jordan.pitt...@gmail.com>
Subject Re: performance tuning - where does the slowness come from?
Date Tue, 04 May 2010 11:02:30 GMT
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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