Each client's scripts execute independently of each other. I suspect that each get's it's own "thread" in the server. The only way that one client's script can affect the execution of another client's script is at the data level--by changing data accessed by the other client's script or by edit locking records.
Within a given client session, only one script is performed by another. If a new script starts executing--as can happen if the first script trips a script trigger or when one script executes a Perform Script call, the first script s paused until the new script exits. FileMaker Advanced's script debugger can be very enlightening when dealing with issues caused by one script tripping the trigger for another script.
Note that "Halt Script" will halt all paused scripts in a given client's session but has no effect on the scripts of other users.
What i have done is that when one user trigger the script, the script will run and find records related to the browsing or find record in that layout.
then it will import only records related to that record to another database. My worry is that during that process if another user execute, wil it terminate the process of importing & updating records in another databse and start triggering for other user.
both are accesing different records but both records are imported to same database.