At any point in the execution of a script, a shared variable can be accessed only from within the block of code that has explicitly been granted access to it. Request access to shared variables by using the access statement.
If no other thread currently has access to any of the shareable variables listed, 4Test executes the specified statements. Otherwise, 4Test blocks the thread where the access statement occurs until access can be granted to all the shareable variables listed. At that point, 4Test blocks competing threads and executes the blocked thread.