1 Reply Latest reply on Oct 4, 2018 3:56 AM by sshriram09

    How to set heap size and GC method (to G1)

    wildflower108
    wildflower108 Jun 25, 2018 6:48 AM
      1. I am trying to do two things:
      3. 1)Change GC to G1
      4. 2)Change default to use Large Memory Pages
      6. I am running JBoss 7 in standalone mode, this is what I did:
      7. #more standalone.conf
      8. ***snip***
      10. #
      11. # Specify options to pass to the Java VM.
      12. #
      13. if [ "x$JAVA_OPTS" = "x" ]; then
      14.    JAVA_OPTS="-Xms1303m -Xmx1303m -XX:MetaspaceSize=96M -XX:MaxMetaspaceSize=256m -Djava.net.preferIPv4Stack=true" XX:+UnlockExperimentalVMOptions -XX:+UseG1GC
      15.    JAVA_OPTS="$JAVA_OPTS -Djboss.modules.system.pkgs=$JBOSS_MODULES_SYSTEM_PKGS -Djava.awt.headless=true"
      16. else
      17.    echo "JAVA_OPTS already set in environment; overriding default settings with values: $JAVA_OPTS"
      18. fi
      20. ***snip***
      22. I restarted standalone.sh but it appears that the values are not being picked up, see below:
      24. [root@localhost bin]# ps -ef | grep java
      25. root      7895  7846  1 08:36 pts/1    00:00:19 /usr/lib/jvm/java-1.8.0-openjdk/bin/java -D[Standalone] -server -verbose:gc -Xloggc:/opt/jboss-eap-7.1/standalone/log/gc.log -XX:+PrintGCDetails -XX:+PrintGCDateStamps -XX:+UseGCLogFileRotation -XX:NumberOfGCLogFiles=5 -XX:GCLogFileSize=3M -XX:-TraceClassUnloading -Djboss.modules.system.pkgs=org.jboss.byteman -Djava.awt.headless=true -Dorg.jboss.boot.log.file=/opt/jboss-eap-7.1/standalone/log/server.log -Dlogging.configuration=file:/opt/jboss-eap-7.1/standalone/configuration/logging.properties -jar /opt/jboss-eap-7.1/jboss-modules.jar -mp /opt/jboss-eap-7.1/modules org.jboss.as.standalone -Djboss.home.dir=/opt/jboss-eap-7.1 -Djboss.server.base.dir=/opt/jboss-eap-7.1/standalone
      27. [root@localhost bin]# java -XX:+PrintCommandLineFlags -version
      28. -XX:InitialHeapSize=46999552 -XX:MaxHeapSize=751992832 -XX:+PrintCommandLineFlags -XX:+UseCompressedClassPointers -XX:+UseCompressedOops -XX:+UseParallelGC
      29. openjdk version "1.8.0_171"
      30. OpenJDK Runtime Environment (build 1.8.0_171-b10)
      31. OpenJDK 64-Bit Server VM (build 25.171-b10, mixed mode)
      33. Is  default heap size different from Jboss jvm heap size?
      34. Where can I change the default heap size?
      35. Where can I manage the standalone JVM heap size?
      36. How do I set GC to type G1
      37. How to enable large memory pages
        • 1. Re: How to set heap size and GC method (to G1)
          sshriram09
          sshriram09 Oct 4, 2018 3:56 AM (in response to wildflower108)

          Is  default heap size different from Jboss jvm heap size?

           

          >> The default JVM heap size for JBoss in standalone mode is set in standalone.conf which is -Xms1303m -Xmx1303m

           

          JAVA_OPTS="-Xms1303m -Xmx1303m -XX:MetaspaceSize=96M -XX:MaxMetaspaceSize=256m -Djava.net.preferIPv4Stack=true"

           

          Where can I change the default heap size? Where can I manage the standalone JVM heap size?

           

          >> You can modify default heap size in standalone.conf

           

          How do I set GC to type G1

           

          >> Append -XX:+UseG1GC option withinJAVA_OPTS in standalone.conf

           

          How to enable large memory pages

           

          >> Append-XX:+UseLargePages within JAVA_OPTS in standalone.conf

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