leyantech / jstart Goto Github PK

potential use case: inject LD_PRELOAD to enable usage of jemalloc.

introduction to tiered compilation: https://www.baeldung.com/jvm-tiered-compilation

candidate rule parameters:

• c2=on expands to -XX:+TieredCompilation -XX:TieredStopAtLevel=4
• c2=off expands to -XX:+TieredCompilation -XX:TieredStopAtLevel=1
• c2=auto behaves just like c2=on when max memory is above 300MB, otherwise behaves like c2=off
• c2=[0|1|2|3|4] expands to -XX:+TieredCompilation -XX:TieredStopAtLevel=<n> , where n is the level number supplied via the parameter

Currently jstart only do jvm option expanding automatically, classpath(-cp) and main class name should be specified explicitely.

For example, jstart -cp server.jar com.leyantech.example.ServiceMain or jstart -jar server.jar is required to start the example java service.

With the support of classpath/main class auto discovery, the above command could be simplified to jstart.

Following is some classpath/main class rules suitable for java applications in docker containers:

1. shade jar-find the jar file with largest size in the current working dir, and expand java command with -jar <jar-found>.jar
2. lib dirs: treat a sub directory with jar files as the class path, and expand java command with -cp "libs/*"