Why concurrency matters in Ruby - See It in Action

Why concurrency matters in Ruby

📖 Scenario: Imagine you run a small online store. You want your website to handle many customers at the same time without slowing down. This is where concurrency helps your Ruby program do many things at once smoothly.

🎯 Goal: You will create a simple Ruby program that shows how concurrency lets your program do multiple tasks at the same time. This helps your store serve many customers quickly.

📋 What You'll Learn

Create a list of tasks representing customer orders

Set a limit for how many tasks can run at the same time

Use Ruby threads to process tasks concurrently

Print messages showing when each task starts and finishes

💡 Why This Matters

🌍 Real World

Concurrency helps websites and apps handle many users or tasks at once without slowing down.

💼 Career

Understanding concurrency is important for Ruby developers building fast, responsive applications.

1

Create a list of customer orders

Create an array called orders with these exact strings: 'Order 1', 'Order 2', 'Order 3', 'Order 4', 'Order 5'.

Ruby

# Create an array called orders with 5 order names
# Your code here

Need a hint?

Use square brackets [] to create an array and put the order names inside quotes separated by commas.

2

Set the maximum number of concurrent tasks

Create a variable called max_threads and set it to 2 to limit how many orders can be processed at the same time.

Ruby

orders = ['Order 1', 'Order 2', 'Order 3', 'Order 4', 'Order 5']
# Set max_threads to 2
# Your code here

Need a hint?

Just write max_threads = 2 on a new line.

3

Process orders concurrently using threads

Use a threads array to hold threads. Use a for loop with variable order to go through orders. Inside the loop, create a new thread that prints "Starting #{order}", sleeps for 1 second, then prints "Finished #{order}". Add the thread to threads. If the number of threads reaches max_threads, wait for the first thread to finish before continuing.

Ruby

orders = ['Order 1', 'Order 2', 'Order 3', 'Order 4', 'Order 5']
max_threads = 2
# Use threads to process orders concurrently
# Your code here

Need a hint?

Use Thread.new to create a thread. Use threads.shift.join to wait for the oldest thread when max_threads is reached.

4

Print the final output showing concurrency

Run the program to print messages showing when each order starts and finishes. The output should show that up to 2 orders run at the same time.

Ruby

orders = ['Order 1', 'Order 2', 'Order 3', 'Order 4', 'Order 5']
max_threads = 2
threads = []
for order in orders
  threads = max_threads
    threads.shift.join
  end
end
threads.each(&:join)
# Run the program to see output

Need a hint?

Run the program and watch the messages. You should see two orders starting before any finish, showing concurrency.