Forked from huynhbaoan/Useful JMX metric to monitor Java GC
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April 22, 2020 10:50
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Recently, I use JMXterm to collect info about Java JVM via JMX and MBeans. Here is a short note. | |
- Download JMXterm | |
https://sourceforge.net/projects/cyclops-group/files/jmxterm/1.0.0/jmxterm-1.0.0-uber.jar/download | |
- Run JMXterm | |
java -jar jmxterm-1.0.0-uber.jar --url localhost:<jmx listen port> | |
- All MBeans from java.lang | |
$>domain java.lang | |
$>beans | |
java.lang:name=CMS Old Gen,type=MemoryPool | |
java.lang:name=Code Cache,type=MemoryPool | |
java.lang:name=CodeCacheManager,type=MemoryManager | |
java.lang:name=Compressed Class Space,type=MemoryPool | |
java.lang:name=ConcurrentMarkSweep,type=GarbageCollector | |
java.lang:name=Metaspace Manager,type=MemoryManager | |
java.lang:name=Metaspace,type=MemoryPool | |
java.lang:name=Par Eden Space,type=MemoryPool | |
java.lang:name=Par Survivor Space,type=MemoryPool | |
java.lang:name=ParNew,type=GarbageCollector | |
java.lang:type=ClassLoading | |
java.lang:type=Compilation | |
java.lang:type=Memory | |
java.lang:type=OperatingSystem | |
java.lang:type=Runtime | |
java.lang:type=Threading | |
- Usually, we want to know how many time a garbage collection happen and how long a garbage collection is, so we use 2 MBeans | |
java.lang:name=ParNew,type=GarbageCollector (young GC) | |
java.lang:name=ConcurrentMarkSweep,type=GarbageCollector (in this case, I use CMS as major GC) | |
Now, let's explore inside | |
$>bean java.lang:name=ParNew,type=GarbageCollector$>info | |
#mbean = java.lang:name=ParNew,type=GarbageCollector | |
#class name = sun.management.GarbageCollectorImpl | |
# attributes | |
%0 - CollectionCount (long, r) | |
%1 - CollectionTime (long, r) | |
%2 - LastGcInfo (javax.management.openmbean.CompositeData, r) | |
%3 - MemoryPoolNames ([Ljava.lang.String;, r) | |
%4 - Name (java.lang.String, r) | |
%5 - ObjectName (javax.management.ObjectName, r) | |
%6 - Valid (boolean, r) | |
#there's no operations | |
# notifications | |
%0 - javax.management.Notification(com.sun.management.gc.notification) | |
Here, we care about CollectionCount and CollectionTime. Let's do a simple query. | |
$>get CollectionCount | |
#mbean = java.lang:name=ParNew,type=GarbageCollector: | |
CollectionCount = 546; | |
So, we can do something similar to fetch the query result to a time-series database, then have grafana draw a graph for us | |
- Query by Zabbix Zabbix jmxagent | |
Define an item with a key like this: | |
jmx["java.lang:type=GarbageCollector,name=ParNew","CollectionCount"] | |
- Query by collectd JMX plugin. | |
Well, this is more complicated to define, because of the plugin configuration. We can take an example here: https://gist.github.com/huynhbaoan/e2cf40654649237cd6ca495ce5a9e13b | |
And the offical document: https://collectd.org/wiki/index.php/Plugin:GenericJMX | |
I will update collectd configurations later, if we decide to use this for our monitor solution. | |
- TL; DR: | |
Here is a short list of key to apply on Zabbix jmx agent. You can use these MBeans info to configure collectd plugin. | |
jmx["java.lang:type=GarbageCollector,name=ParNew","CollectionCount"] | |
jmx["java.lang:type=GarbageCollector,name=ParNew","CollectionTime"] | |
jmx["java.lang:type=GarbageCollector,name=ConcurrentMarkSweep","CollectionCount"] | |
jmx["java.lang:type=GarbageCollector,name=ConcurrentMarkSweep","CollectionTime"] | |
jmx["java.lang:type=Memory","HeapMemoryUsage.used"] | |
jmx["java.lang:type=Memory","HeapMemoryUsage.max"] | |
jmx["java.lang:type=Memory","NonHeapMemoryUsage.used"] | |
jmx["java.lang:type=Memory","NonHeapMemoryUsage.max"] | |
jmx["java.lang:type=MemoryPool,name=Par Eden Space","Usage.used"] | |
jmx["java.lang:type=MemoryPool,name=Par Survivor Space","Usage.used"] | |
jmx["java.lang:type=MemoryPool,name=CMS Old Gen","Usage.used"] | |
jmx["java.lang:type=MemoryPool,name=CMS Perm Gen","Usage.used"] | |
jmx["java.lang:type=MemoryPool,name=Code Cache","Usage.used"] | |
jmx["java.lang:type=Threading","DaemonThreadCount"] | |
jmx["java.lang:type=ClassLoading","LoadedClassCount"] | |
jmx["java.lang:type=ClassLoading","UnloadedClassCount"] | |
jmx["java.lang:type=OperatingSystem","ProcessCpuLoad"] | |
jmx["java.lang:type=Threading","ThreadCount"] | |
jmx["java.lang:type=Compilation","TotalCompilationTime"] |
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