Question

When a signal is performed on a condition inside a monitor, the signaling process can either continue its execution or transfer control to the process that is signaled. How would the solution to the preceding exercise differ with these two different ways in which signaling can be performed?

Answer 1

Answer: The solution to the previous exercise is correct under both situations.However, it could suffer from the problem that a process might be awakened only to discover that it is impossible for it to make forward progress which can be either because there was insufficient slack to start with when a process was awakened or if an intervening process gets control,obtains the monitor and starts accessing the file.

The signal also transfers control and the monitor from the current thread to the target, one can check whether the target would indeed be able to make a positive progress and perform the signal only if it it were possible and the “while” loop for the waiting thread can be change by an “if” condition since it is guaranteed that the condition will be completed when the process is woken up.