How to set JVM heap size at run time when running jmeter in distributed testing using docker

I have below test infrastructure:

1. 3 instances (master + 2 slaves), dockerized
2. Run command from jmeter master (default 512m is used in all 3 machines) sudo docker exec -i master /bin/bash -c "/jmeter/apache-jmeter-3.1/bin/jmeter -n -t /home/librarian_journey_Req.jmx -Djava.rmi.server.hostname=yy.yy.yy.yy -Dclient.rmi.localport=60000 -R1xx.xx.xx.xx -j jmeter.log -l result.csv"

the above command works fine and getting results also. however wanted to increase the heap size to 3gb at run time.

I had tried using below command:

sudo docker exec -i master /bin/bash -c "JVM_ARGS="-Xms1024m -Xmx1024m" /jmeter/apache-jmeter-3.1/bin/jmeter -n -t /home/librarian_journey_Req.jmx -Djava.rmi.server.hostname=10.135.104.138 -Dclient.rmi.localport=60000 -R10.135.104.135,10.135.104.139 -j jmeter.log -l result.csv"

after running the above command nothing happens. Please guide how can it be increased.

You can override environment variables when running containers. Also, usually you don't need to use sudo to execute docker. So try this:

docker exec -i -e JVM_ARGS="-Xms1024m -Xmx1024m" master /bin/bash ...