Running Java / Jython process in the background
I got the answer on github: https://github.com/jythontools/jython/issues/148

Solution is summarized below.

when running with jython, 

export JAVA_OPTS="-Dpython.launcher.tty=false"
jython a_jython_script.py &amp;


Invoking with java add -Dpython.launcher.tty=false

/Library/Java/JavaVirtualMachines/jdk1.8.0_212.jdk/Contents/Home/bin/java -Xmx512m -Xss2560k -classpath ../../../../../../usr/local/Cellar/jython/2.7.1/libexec/jython.jar:. -Dpython.home=../../../../../../usr/local/Cellar/jython/2.7.1/libexec -Dpython.executable=../../../../../../usr/local/Cellar/jython/2.7.1/libexec/bin/jython -Dpython.launcher.uname=darwin -Dpython.launcher.tty=true -Dfile.encoding=UTF-8 -Dpython.launcher.tty=false org.python.util.jython a_jython_script.py &amp;