shellattach spawns a Groovy Shell Server on an already running JVM.
shellattach requires socat to be able to run.
shellattach builds with Gradle.
git clone https://github.com/oxtoacart/shellattach.git
cd shellattach
gradle shadow
Find your Java process id using jps (comes with Java).
> jps
55885 lantern-1.1.0-beta2-SNAPSHOT.jar
55918 Jps
68818
Start the remote shell on port 6789 for pid 55885
> ./shellstart 6789 55885
Loaded shellattach agent, listening for socat connection at port 6789
Connect to the remote shell
> ./shellconnect 6789
Groovy Shell (2.1.9, JVM: 1.7.0_45)
Type 'help' or '\h' for help.
-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
groovy:000>
You're now in a Groovy shell that has full access to the JVM running as pid 55885!
To connect again later, there's no need to rerun shellstart, just use shellconnect.