Shagufta, thank you very much for trying to help me. I think I understood what you want to say, even if my English is not really good…
So, I tried the following tests :
1) I deleted the parallelGateway, and simply replaced it by two sequenceFlow comming from start node, and respectively going to humanTask1 and humanTask2. Then, I don't have parallelGateway anymore in my process.
The result : the process doesn't end (NOK : it should).
2) I tried to add <code><terminateEventDefinition activiti:terminateAll="true"></terminateEventDefinition></code> to the end node.
The result : the process ends, and the caller process also ends (OK).
3) I tried to add <code><terminateEventDefinition activiti:terminateAll="false"></terminateEventDefinition></code> to the end node (terminateAll is false, vs true in the previous test).
The result : the process ends (OK), and the caller process also ends ( NOK : it shouldn't).
All of that really doesn't make sense to me…
If, by chance, an activiti developper could have a look, and tell me where, in the activiti code, I could debug to see what happens and point what I am doing wrong…