"kukeltje" wrote : a special task, one special variable, one.... you name it.... The issue that you have to act on this special task in one way or another (when does concurrency end? what if this lock stays by accident, what do you return to the other token). Sound like your trying to invent a mechanism that maybe should be in the engine... Yes but the special task is shared. Two threads would race to acquire the special task (read lock) but ultimately a task is stored in the database so wouldn't the concurrency end when accessing a row in the task instance table? It seems to me as if there should be a mechanism in the engine to lock a process when there are multiple tokens. There may need to be a timer on the task to release it if it doesn't get released automatically or something. dOoMi. I would really appreciate it if you could write a paragraph on your understanding of the situation. I'm not deeply into Hibernate and have a really tight deadline for this stuff. To be fair I'm not familiar enough with jbpm yet to know at what level I need to provide synchronization. I presume it would be at the processInstance level. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4163492#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...