HuiSheng Xu [http://community.jboss.org/people/rebody] replied to the discussion "jBPM- Transaction isolation level" To view the discussion, visit: http://community.jboss.org/message/541212#541212 -------------------------------------------------------------- Hi Alexander, Commonly, jBPM 4 used optimistic lock to prevent concurrent thread modify the same record in database.  When there were splited execution need to be merged, e.g. in the JoinActivity, jBPM 4 used LockMode.UPGRADE to lock the parent execution. It is means that it will send a SQL likes 'select * from T for update' to lock a record in database and prevent other thread modify this line.   So, if you want to do some integration work, you should consider about using optimistic lock. -------------------------------------------------------------- Reply to this message by going to Community [http://community.jboss.org/message/541212#541212] Start a new discussion in jBPM at Community [http://community.jboss.org/choose-container!input.jspa?contentType=1&...]