Zheng Tech Blog

Although there is a similar blog entry on this topic, I’d rather to blog it anyway for my own reference. If the WebLogic Server was installed on Linux and when starting, you might see the following message: What happened is the default JRockit JVM prefers to uses large pages for Java heap but the Linux OS is not setup yet for this option. HugePages is a feature integrated into the Linux kernel 2.6. It’s a method to have larger page size that is useful for working with large memory. HugePages is userful for both 32-bit and 64-bit configurations. Its size varies from 2MB to 256MB, depending on the kernel version and the hardware architecture. Using HugePages reduces the OS maintenance of page states, and increases Translation Lookaside Buffer (TLB) hit ratio. Run the following will show a filesystem of type hugetlbfs configured in the kernel: cat /proc/filesystems First, we need to create the hugepages director...

Today I had an issue that the JRockit mission control cannot be started. The problem is when trying to start mission control from windows programs, the mission control splash flashed and disappeared right away. Something is blocking the process to be started properly. The key to this issue is to start JRockit mission control using debug command-line. From windows: %JROCKIT_HOME%\bin\jrmc -consoleLog 2>1& | more Here was the output I got: Dec 25, 2010 11:07:57 PM com.jrockit.mc.rjmx.internal.RJMX initializeSettings INFO: Reading console settings from C:\Documents and Settings\jzheng\.jrmc\4.0.1\rjmx.4.0.1.xml Dec 25, 2010 11:07:58 PM com.jrockit.mc.rjmx.core.connections.internal.ConnectionDescriptorRepository diffAgainstConsoleModel WARNING: Found discrepancy in Browser View - could not find 10.0.0.4:4711 in view. Removing it from the model... !SESSION 2010-12-25 23:07:56.656 eclipse.buildId=unknown java.version=1.6.0_20 java.vendor=Oracle Corporation BootLoader co...

To enable a JRockit JVM for remote management, the external management agent must be started. There are two ways to start the management agent: 1. Start the JVM with the -Xmanagement command-line. JROCKIT_HOME/bin/java -Xmanagement:ssl=false,authenticate=false,port=4711 2. use JRCMD when the JVM is already started. use JRCMD to find the PID of the JVM (4620 for example) JROCKIT_HOME/bin/jrcmd 4620 start_management_server ssl=false authenticate=false port=4711 autodiscovery=true The command line will not produce any output if everything goes well.