The ultimate guide to Ruby concurrency interviews. Developed by FAANG engineers, this course covers Monitors, Deferred Callbacks and problem-solving strategies for Reader-Writer and Dining Philosopher Problems.

Concurrency in Ruby is one of the most complex and advanced topics brought up during senior engineering interviews. Knowledge of concurrency and multithreading can put interviewees at a considerable advantage. This course lays the foundations of advanced concurrency and multithreading and explains concepts such as Monitors and Deferred Callbacks in depth. It also builds simple and complete solutions to popular concurrency problems that can be asked about in interviews like the Reader-Writer Problem and the Dining Philosopher Problem. While prior knowledge of concurrency is not required to follow through with this course, familiarity with the basics of Ruby would be helpful.

Ruby Concurrency for Senior Engineering Interviews

<div class="card">
   # Asynchronous to Synchronous Problem
    <div class="ans">
<p><i>This is an actual interview question asked at Netflix.</i></p>
<p>Imagine we have an <code class="clazz">AsyncExecutor</code> class that performs some useful task asynchronously via the method <code class="mthd">execute()</code>. In addition, the method accepts a function object that acts as a callback and gets invoked after the asynchronous execution is done. The definition of the involved classes is below. The asynchronous work is simulated using sleep. A passed-in call is invoked to let the invoker take any desired action after the asynchronous processing is complete.</p>
## Executor Class
<b>

```ruby
class AsyncExecutor

  def work(callback)
    sleep(5)
    callback.call()
  end

  def execute_async(callback)
    Thread.new do
      work(callback)
    end
  end
end
```
</b>
<p>An example run would be as follows:</p>
</div>
</div>



<div>
   # Asynchronous to Synchronous Problem
    <div>
<p><i>This is an actual interview question asked at Netflix.</i></p>
<p>Imagine we have an <code>AsyncExecutor</code> class that performs some useful task asynchronously via the method <code>execute()</code>. In addition, the method accepts a function object that acts as a callback and gets invoked after the asynchronous execution is done. The definition of the involved classes is below. The asynchronous work is simulated using sleep. A passed-in call is invoked to let the invoker take any desired action after the asynchronous processing is complete.</p>
## Executor Class
<b>

```ruby
class AsyncExecutor

  def work(callback)
    sleep(5)
    callback.call()
  end

  def execute_async(callback)
    Thread.new do
      work(callback)
    end
  end
end
```
</b>
<p>An example run would be as follows:</p>
</div>
</div>



In this lesson, we will study a​ real-life interview question asking to convert asynchronous execution to synchronous execution.

The Basics

API Overview

Brief Intro to Asynchronous Programming

Interview Practice Problems

Bonus Questions

Epilogue

Asynchronous to Synchronous Problem

Asynchronous to Synchronous Problem

Executor Class