incubator-cassandra-user mailing list archives

Site index · List index
Message view « Date » · « Thread »
Top « Date » · « Thread »
From Ran Tavory <ran...@gmail.com>
Subject performance tuning - where does the slowness come from?
Date Tue, 04 May 2010 06:20:47 GMT
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;
...

Mime
View raw message