Ripping the covers off Java and seeing what’s configured

I needed to see what definitions were being used by Java applications like z/OSMF and Zowe. I could not find an easy way, so I had to resort to taking a dump!

Use the Unix command ps -ef to display all of the Unix threads, and what they are running

For example

IBMUSER:/global/zosmf/configuration: >ps -ef  |grep zosmf                                                                         
OMVSKERN   50397205   83951638  - 18:36:28 ?         6:48 /usr/lpp/zosmf/liberty/lib/native/zos/s390x/bbgzsrv --clean zosmfServer 
  IZUSVR   50397230   50397231  - 18:36:18 ?         0:00 /usr/lpp/zosmf/liberty/lib/native/zos/s390x/bbgzangl COLD=N NAME=IZUANG1
       

Send a command to take a dump

kill -QUIT 50397205

This created a dump START1.JVM.IZUSVR0.D250206.T184027.X001 and a file /global/zosmf/data/logs/zosmfServer/javacore.20250206.184027.50397205.0002.txt

The .txt file is human readable, and may have all the data you need.

Extract information from the binary dump

Use the same Java as the application was using

1. Copy the dump dataset (known as a TRANSACTION DUMP) to a Unix file, such as dump
   cp "//'START1.JVM.IZUSVR0.D250206.T184027.X001 '" dump
2. extract a java dump from TRANSACTION DUMP using /usr/lpp/java/J11.0_64/bin/jextract dump -v, this creates a dump.zip
3. Use the jdmpview to look at the dump.
4. Run dump viewer /usr/lpp/java/J11.0_64/bin/jdmpview -J-Xmx768m -zip dump.zip
5. Run info thread in jdmpview to display information about current thread java/native stack trace.