Will the Guru

PLEASE NOTE: Getting thread dump and heap dump are stop the world operations.

How to get thread dump

1. Confirm the server isn’t getting more requests
   • Either detach from application load balancer or block from getting new requests
2. Get java process ID using jps
   • jps -v
3. Use jstack to get thread dump file
   • jstack -l $PID >> threaddump.log
4. Analyze from https://fastthread.io/

How to get heap dump

1. Confirm the server isn’t getting more requests
   • Either detach from application load balancer or block from getting new requests
2. Get java process ID using jps
   • jps -v
3. Use jmap to get heap dump file
   • jmap -dump:format=b,file=headump.hprof $PID
4. (Recommended) Zip the .hprof file into .tar.gz
5. Analyze from MAT(Eclipse Memory Analyzer) or https://heaphero.io or https://www.yourkit.com/

How to generate gc.log

1. To generate gc.log, need to add JVM start-up arguments
2. Analyze from https://gceasy.io/

-verbose:gc -Xloggc:${LOG_PATH}/gc/gc.`date '+%Y%m%d%H%M'`.log -XX:+PrintGCDetails -XX:+PrintGCDateStamps

How to make a file into .tar.gz file

tar -zcvf [FILE_NAME.tar.gz] [FILE_NAME]
ex) tar -zcvf aaa.tar.gz abc

tar -cvf [FILE_NAME.tar] [FILE_NAME]
ex) tar -cvf aaa.tar abc