Implementing a Barrier

Implementing a Barrier

A barrier can be thought of as a point in the program code, which all or some of the threads need to reach at before any one of them is allowed to proceed further.

Solution

A barrier allows multiple threads to congregate at a point in code before any one of the thread is allowed to move forward. C# and most other languages provide libraries which make barrier construct available for developer use. Even though we are re-inventing the wheel but this makes for a good interview question.

We can immediately realize that our solution will need a count variable to track the number of threads that have arrived at the barrier. If we have n threads, then n-1 threads must wait for the nth thread to arrive. This suggests we have the n-1 threads execute the wait method and the nth thread wakes up all the asleep n-1 ...