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;
>> ...
>