title: activemq memory usage 4 times greater than Maximum heap allocated
body: <p>I have below configuration for my java actvemq process where Xmx is 15360M 
  but when I see the process usage of memory using glance I see  RSS 41.8gb 
  and VSS  51.6gb . pmap |grep total gives me  total 54059348K. I 
  am not sure what is happening in activemq that is causing this much amount 
  of memory being utilized. While heap usage is pretty low till 60%. </p>
  
  <p>In the output of pmap I see lot of anon blocks. Please find attached PMAP 
  output </p>
  
  <pre><code>/XXXXX 111922      1 22 14:30 pts/0    00:04:26 
  /u/users/user/jdk1.7.0_71/bin/java -Xms1024M -Xmx15360M -Xss512K 
  -XX:+UseG1GC -XX:NewRatio=4 -XX:InitiatingHeapOccupancyPercent=45 
  -XX:+PrintGCDetails -XX:+PrintGCDateStamps -Xloggc:/x/logs/AMQGC.log 
  -XX:+UseGCLogFileRotation -XX:NumberOfGCLogFiles=10 -XX:GCLogFileSize=20M 
  -Djava.util.logging.config.file=logging.properties 
  -Djava.security.auth.login.config=/u/users/user/POSInterfaces/apache-activemq-5.13.2//conf/login.config 
  -Dcom.sun.management.jmxremote -Dcom.sun.management.jmxremote 
  -Djava.awt.headless=true 
  -Djava.io.tmpdir=/u/users/user/POSInterfaces/apache-activemq-5.13.2//tmp 
  -Dactivemq.classpath=/u/users/user/POSInterfaces/apache-activemq-5.13.2//conf:/u/users/user/POSInterfaces/apache-activemq-5.13.2//../lib/: 
  -Dactivemq.home=/u/users/user/POSInterfaces/apache-activemq-5.13.2/ 
  -Dactivemq.base=/u/users/user/POSInterfaces/apache-activemq-5.13.2/ 
  -Dactivemq.conf=/u/users/user/POSInterfaces/apache-activemq-5.13.2//conf 
  -Dactivemq.data=/u/users/user/POSInterfaces/apache-activemq-5.13.2//data 
  -jar /u/users/user/POSInterfaces/apache-activemq-5.13.2//bin/activemq.jar 
  start/ 
  </code></pre>
  
  <p>Please find pmap file <a href="http://activemq.2283324.n4.nabble.com/file/t378515/pmap.txt" rel="nofollow noreferrer">here</a></p>