I have a process in which one store entity task retrieves a db value, puts it in a variable, goes to script task next, update the variable's value, goes to another store entity task and stores this value back in db. I was wondering, what happens when multiple instances of this process gets started at same times. Would there be concurrent access of db when process instance's executions reach store entity task at same time? Does this result in corrupting data while updating due to race conditions b/w multiple instances of process being executed.
To avoid this, I want to achieve some kind of lock scenario on these tasks where if one process instance arrived at the Store entity task, the other one should wait till it completes the task.
Any advise on this is much appreciated! 
