how can I set the worker jvm dynamically?

[zhonghong...@yy.com]

the jvm for my spout is too small, but when I set the jvm like this, it doesn't 
work. so what's the correct way to do so ?
in my spout :
@Override
public Map<String, Object> getComponentConfiguration() {
Config conf = new Config();
//int tickFrequencyInSeconds = 10;
conf.put(Config.WORKER_CHILDOPTS, "-Xmx1024m");
return conf;
}