Setting heap size parameters by workers.childopts and supervisor.childopts

[sam mohel]

i'm using 0.10.2 version . i tried to write in the code
conf.put(Config.WORKER_CHILDOPTS, "-Xmx4g");
conf.put(Config.SUPERVISOR_CHILDOPTS, "-Xmx4g");

but i didn't touch any affect . Did i write the right configurations ?
Does this value is the largest ?