Search⌘ K
AI Features
Home
Courses
C# Concurrency for Senior Engineering Interviews

Unisex Bathroom Problem

Explore the Unisex Bathroom concurrency problem where men and women must not use the bathroom simultaneously and no more than three employees can be inside at once. Learn how to model this scenario in C# with monitors and semaphores, manage thread synchronization, and prevent deadlocks while handling shared state variables.

We'll cover the following...

Unisex Bathroom Problem

A bathroom is being designed for the use of both males and females in an office but requires the following constraints to be maintained:

  • There cannot be men and women in the bathroom at the same time.

  • There should never be more than three employees in the bathroom simultaneously.

The solution should avoid deadlocks. For now, though, don’t worry about starvation.

widget

Solution

First let us come up with the skeleton of our Unisex Bathroom class. We want to model the problem programmatically first. We'll need two APIs, one that is called by a male to use the bathroom and another one that is called by the woman to use the bathroom. Initially, our class looks like the following

C#
public class UnisexBathroom
{
    public UnisexBathroom()
    {
    }
    public void maleUseBathroom()
    {
    }
    public void femaleUseBathroom()
    {
    }
}

Let us try to address the first problem of allowing either men or women to use the bathroom. We'll worry about the max employees later. We need to maintain state in a variable to track which gender is currently using the bathroom. Let's call this variable inUseBy. The variable inUseBy will take on the values female, male or none to denote the gender currently using the bathroom.

We'll also have a ...