Hi Maciej,
In jBPM 3.x, they use discriminator and nOutOfM to decide how to solve the split executions that joined in the Join node. Whether automaticly terminate the rest of splited execution is really a problem. Maybe there could be a attribute to decide how we could handle that. Please refer this issue JBPM-2720
https://jira.jboss.org/browse/JBPM-2720