Hiring guide for Elixir Tasks Engineers

Elixir Tasks Developer Hiring Guide

Elixir Tasks is a computer programming language designed for building scalable and maintainable applications. It was developed by José Valim in 2011, with its source code openly available on GitHub. Elixir leverages the Erlang VM, known for running low-latency, distributed, and fault-tolerant systems. The language's key features include metaprogramming with macros and polymorphism via protocols. Elixir Tasks specifically refers to the built-in tooling for background processing within this robust language ecosystem.

Ask the right questions secure the right Elixir Tasks talent among an increasingly shrinking pool of talent.

First 20 minutes

General Elixir Tasks app knowledge and experience

The first 20 minutes of the interview should seek to understand the candidate's general background in Elixir Tasks application development, including their experience with various programming languages, databases, and their approach to designing scalable and maintainable systems.

How would you define Elixir Tasks?
Elixir Tasks is a built-in mix task that allows you to run arbitrary elixir code in the context of your application.
What are the benefits of using Elixir Tasks?
Elixir Tasks provides a way to run code concurrently, manage background jobs, and handle distributed computing tasks.
Describe the difference between Elixir Tasks and GenServer.
Elixir Tasks are used for short-lived processes while GenServer is used for long-lived processes. Tasks are simpler and do not maintain state, whereas GenServer can maintain state.
How would you handle errors in Elixir Tasks?
Errors in Elixir Tasks can be handled using the Task module's built-in functions such as Task.await/2 and Task.yield/2 which can return {:error, reason} tuples.
What is the use of Task.Supervisor in Elixir?
Task.Supervisor is a module in Elixir that allows you to supervise tasks, handling failures and ensuring that the system continues to run.
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What you’re looking for early on

Does the candidate have a solid understanding of Elixir Tasks?
Can the candidate demonstrate problem-solving skills?
Is the candidate familiar with concurrent and distributed computing?
How well does the candidate understand OTP (Open Telecom Platform)?

Next 20 minutes

Specific Elixir Tasks development questions

The next 20 minutes of the interview should focus on the candidate's expertise with specific backend frameworks, their understanding of RESTful APIs, and their experience in handling data storage and retrieval efficiently.

How would you use Task.Supervisor to supervise a task?
You can use Task.Supervisor.async/2 to start a task under a supervisor. If the task crashes, the supervisor will be notified and can take appropriate action.
What are the differences between Task.async and Task.start?
Task.async starts a task that is linked to the current process, while Task.start starts a task without linking. If a task started with Task.async crashes, it will bring down the parent process unless it is trapped or supervised.
How would you use Elixir Tasks for concurrent programming?
You can use Task.async/1 to start multiple tasks concurrently and then use Task.await/1 to collect the results. This allows you to run multiple operations at the same time and collect the results when they are all finished.
Describe how Elixir Tasks handle timeouts.
Elixir Tasks handle timeouts using the Task.await/2 function. If the task does not complete within the specified timeout, a timeout error is raised.
How would you use Elixir Tasks to run a background job?
You can use Task.start/1 to start a task in the background. The task will run concurrently with the parent process and will not be linked to it, so it will not crash the parent process if it fails.
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The ideal back-end app developer

What you’re looking to see on the Elixir Tasks engineer at this point.

At this point, a skilled Elixir Tasks engineer should demonstrate strong problem-solving abilities, proficiency in Elixir Tasks programming language, and knowledge of software development methodologies. Red flags include lack of hands-on experience, inability to articulate complex concepts, or unfamiliarity with standard coding practices.

Digging deeper

Code questions

These will help you see the candidate's real-world development capabilities with Elixir Tasks.

What does the following Elixir code do?
IO.puts "Hello, World!"
This code prints the string 'Hello, World!' to the console.
What will be the output of the following Elixir code?
IO.inspect([1, 2, 3, 4, 5])
This code will print the list [1, 2, 3, 4, 5] to the console and return the list itself.
What does the following Elixir code do?
Enum.map([1, 2, 3, 4, 5], fn x -> x * 2 end)
This code multiplies each element in the list [1, 2, 3, 4, 5] by 2, resulting in a new list [2, 4, 6, 8, 10].
What does the following Elixir code do?
Task.async(fn -> 1 + 2 end)
This code starts a new process that computes the sum of 1 and 2 asynchronously.

Wrap-up questions

Final candidate for Elixir Tasks Developer role questions

The final few questions should evaluate the candidate's teamwork, communication, and problem-solving skills. Additionally, assess their knowledge of microservices architecture, serverless computing, and how they handle Elixir Tasks application deployments. Inquire about their experience in handling system failures and their approach to debugging and troubleshooting.

What is the purpose of Task.yield in Elixir?
Task.yield is a function in Elixir that allows a process to give up control and allow other processes to run. It is often used in conjunction with Task.await to handle timeouts.
How would you use Elixir Tasks to handle distributed computing tasks?
You can use Task.Supervisor to supervise tasks running on different nodes in a distributed system. The supervisor can handle failures and restart tasks as necessary.
Describe the difference between Task.Supervisor.async and Task.Supervisor.start_child.
Task.Supervisor.async starts a task and links it to the current process, while Task.Supervisor.start_child starts a task without linking it. The async function is used for tasks that should bring down the current process if they fail, while start_child is used for tasks that should be isolated from the current process.

Elixir Tasks application related

Product Perfect's Elixir Tasks development capabilities

Beyond hiring for your Elixir Tasks engineering team, you may be in the market for additional help. Product Perfect provides seasoned expertise in Elixir Tasks projects, and can engage in multiple capacities.