Procedures

Defines procedures which can be helpful for troubleshooting problems with the application

• You will need sometimes to use java tools located in java bin folder, which is not always in the PATH.
• To find the exact Java bin folder, execute the below command

# ls -l /etc/alternatives/java
> /etc/alternatives/java -> /usr/lib/jvm/java-17-openjdk-17.0.0.0.35-1.rolling.el7.x86_64/bin/java

• Java tools often require to provide process PID
• It can be discovered by running the below command:

  # systemctl status promonitor

• The PID is displayed next to the application startup command (22502 in below example)

• If multiple PIDs are displayed, run it multiple times, the right one is the one which persists and never changes.

Heap dump creates a file allowing to inspect memory usage of the application
This is helpful for investigating problems such as memory leaks

• Get the application PID and run following command

[JAVA BIN PATH]/jmap -dump:live,format=b,file=heapdump.hprof [PID]

• Attach the dump file to a ticket. This will help investigating

Note:

• If jmaps returns an error such as well-known file /tmp/.java_pid22502 is not secure: file should be owned by the current user (which is 0) but is owned by 994
• Try running it by prefixing the command with sudo -u promonitor, such as

sudo -u promonitor [JAVA BIN PATH]/jmap -dump:live,format=b,file=heapdump.hprof [PID]

Stack traces helps understanding what the application is doing at a given time.
This helps investigating performance issues, such as slow startup

• Get the application PID and run following command

[JAVA BIN PATH]/jstack PID > stacktrace.log

• Attach stacktrace.log to a ticket