Hi Wojciech, >From the memory metrics and the up time of the RS reported by top seems that JVM has been running for a while, so a good part of the memory pages available for the JVM process have been touched and now are considered as used by to OS. Same thing can happen if -Xms is present and its larger than the default or equal to -Xmx causing those memory pages to be "touched" and considered by the OS as used even when the JVM hasn't claimed that memory for object creation.
BTW, usually when you monitor memory utilization by HBase, you only monitor the JVM metrics and not the memory usage reported by the OS for the HBase process, since that usually is (or will become) a constant value during the life of the process. I hope that helps. esteban. -- Cloudera, Inc. On Wed, Jun 24, 2015 at 2:27 AM, Wojciech Indyk <wojciechin...@gmail.com> wrote: > hello! > I try to monitor memory of my regionservers. I have HBase 0.98 on CDH > 5.3.1. > I can see inconsistency between HBase metrics (here is metrics dump > from HBase UI): > "name" : "Hadoop:service=HBase,name=JvmMetrics", > "modelerType" : "JvmMetrics", > "tag.Context" : "jvm", > "tag.ProcessName" : "IPC", > "tag.SessionId" : "", > "tag.Hostname" : "sqhadoop04.gazeta.pl", > "MemNonHeapUsedM" : 93.26676, > "MemNonHeapCommittedM" : 94.89844, > "MemNonHeapMaxM" : -9.536743E-7, > "MemHeapUsedM" : 8513.122, > "MemHeapCommittedM" : 20330.25, > "MemHeapMaxM" : 20330.25, > "MemMaxM" : 20330.25, > and system "top" monitoring (all of my hbase processes on the > regionserver): > PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND > 19700 hbase 20 0 22.3g 16g 23m S 1.3 8.7 479:47.53 java > 19874 hbase 20 0 107m 2404 556 S 0.7 0.0 9:16.13 hbase.sh > 19873 hbase 20 0 105m 908 556 S 0.0 0.0 0:00.00 hbase.sh > > As we can see there is 16GB according to "top" and ~8.5GB according to > HBase. Why these values are different? > > Kindly regards > Wojciech Indyk >
