StoreWithSemaphore.cs

class Store
{
  private static Semaphore semaphore = new Semaphore(1, 3);

  // ...
  
  async Task DoSomeWork()
  {
    try
    {
       semaphore.WaitOne();
    
       // THE REST OF THE CODE
    }
    finally
    {
       semaphore.Release();
    }
  }
}