Why background processing handles heavy tasks in NestJS - See It in Action

Why Background Processing Handles Heavy Tasks in NestJS

📖 Scenario: You are building a NestJS application that sends welcome emails to new users. Sending emails can take time and slow down the app if done directly during user registration.To keep the app fast and responsive, you will use background processing to handle the email sending task separately.

🎯 Goal: Build a simple NestJS service that queues email sending tasks to a background processor instead of sending emails immediately during user registration.This shows how background processing helps handle heavy tasks without blocking the main app flow.

📋 What You'll Learn

Create a list of new users with their email addresses

Add a configuration variable to set the maximum number of emails to send at once

Use a loop to queue email sending tasks for each user

Add a final method call to start processing the queued email tasks

💡 Why This Matters

🌍 Real World

Background processing is used in real apps to handle slow tasks like sending emails, processing images, or generating reports without slowing down the user experience.

💼 Career

Understanding background processing is important for backend developers to build scalable and responsive applications using NestJS or similar frameworks.

1

Create the list of new users

Create a constant array called newUsers with these exact objects: { id: 1, email: '[e-mail]' }, { id: 2, email: '[e-mail]' }, and { id: 3, email: '[e-mail]' }.

NestJS

# Create the newUsers array with 3 user objects
# Your code here

Need a hint?

Use const newUsers = [ ... ] with objects inside the array.

2

Add max emails per batch configuration

Create a constant called maxEmailsPerBatch and set it to 2 to limit how many emails are sent at once.

NestJS

const newUsers = [
  { id: 1, email: '[e-mail]' },
  { id: 2, email: '[e-mail]' },
  { id: 3, email: '[e-mail]' }
];

# Create maxEmailsPerBatch and set it to 2
# Your code here

Need a hint?

Use const maxEmailsPerBatch = 2; to set the batch size.

3

Queue email sending tasks for each user

Use a for loop with const user of newUsers to iterate over newUsers. Inside the loop, call emailQueue.add(user.email) to queue sending an email to each user's email address.

NestJS

const newUsers = [
  { id: 1, email: '[e-mail]' },
  { id: 2, email: '[e-mail]' },
  { id: 3, email: '[e-mail]' }
];

const maxEmailsPerBatch = 2;

// Loop over newUsers and add each email to emailQueue
// Your code here

Need a hint?

Use for (const user of newUsers) { emailQueue.add(user.email); } to queue emails.

4

Start processing the queued email tasks

Call emailQueue.process(maxEmailsPerBatch) to start sending emails in batches of maxEmailsPerBatch.

NestJS

const newUsers = [
  { id: 1, email: '[e-mail]' },
  { id: 2, email: '[e-mail]' },
  { id: 3, email: '[e-mail]' }
];

const maxEmailsPerBatch = 2;

for (const user of newUsers) {
  emailQueue.add(user.email);
}

// Start processing the email queue with maxEmailsPerBatch
// Your code here

Need a hint?

Call emailQueue.process(maxEmailsPerBatch); to start sending emails.