Should I use worker threads for sending more than 5000 HTTP requests?

If I want to send messages to more than 5000 users in Node.js, which takes a long time, and I don't want it to be render blocking, is "Worker threads" what I need?

The documentation says:

> Workers (threads) are useful for performing CPU-intensive JavaScript operations. They do not help much with I/O-intensive work. The Node.js built-in asynchronous I/O operations are more efficient than Workers can be.

What is the "Node.js built-in asynchronous I/O operations" it is referring to?

I need to loop like more than 5000 contacts:

• store a new row in the database for each contact.
• send a message with an Axios HTTP request to an external API for each contact.

Is this considered as an "I/O operation"?

When using third-party APIs with rate-limiting, I like to pace my asynchronous requests to match their rate limits. The number of concurrent requests will vary based on latency, but it shouldn't ever be enough to overtax your resources.

rateLimiter = {
    paces: {'myList':13},
    starts: {},
    sleep: function(ms) { return new Promise(resolve => setTimeout(resolve, ms)) },
    pace: async function(label) {
            if (this.starts[label]) {
                    let remainingTime=this.paces[label] + this.starts[label] - new Date().getTime();
                    if (remainingTime > 0) await this.sleep(remainingTime);
            }
            this.starts[label]=new Date().getTime();
    }
};

async function processList(myList) {
   for (const member of myList) {
      await rateLimiter.pace('myList');
      APICall(member).then(/* handle it */);
   }
}

Yes, for your use case, the operations you described (storing a new row in the database and sending an HTTP request to an external API for each contact) are considered I/O operations. I/O stands for Input/Output, and it refers to operations that involve reading from or writing to external resources, such as databases, files, or network requests.

Node.js is particularly well-suited for I/O-intensive operations due to its non-blocking, asynchronous nature. When Node.js performs an I/O operation (e.g., reading from a file or making an HTTP request), it doesn't block the entire program's execution while waiting for the operation to complete. Instead, it continues executing other tasks in parallel, making efficient use of resources.

The Node.js built-in asynchronous I/O operations include:

1. File System Operations: Reading and writing files using functions like fs.readFile, fs.writeFile, etc.

2. Network Operations: Making HTTP requests or other network-related tasks using modules like http, https, net, etc.

3. Database Operations: Performing queries and CRUD (Create, Read, Update, Delete) operations on databases using modules like mysql, mongodb, etc.

Now, regarding the use of Worker Threads for your specific scenario:

Worker Threads: As the documentation states, worker threads are primarily useful for CPU-intensive operations. If your task involves a significant amount of computational work that can be parallelized (like heavy calculations), then using Worker Threads could be beneficial. It allows you to offload CPU-intensive tasks to separate threads, leaving the main thread available for other work.

However, for I/O-intensive tasks like the ones you mentioned (database operations and making HTTP requests), using Worker Threads might not provide significant benefits. Node.js's built-in asynchronous I/O model is already designed to handle such tasks efficiently.

Handling I/O-Intensive Tasks Efficiently: To process 5000+ contacts without blocking the event loop and leveraging Node.js's strengths, you can use asynchronous programming techniques, such as Promises, async/await, or callbacks. By doing so, you can initiate I/O operations for each contact, and Node.js will handle them efficiently in a non-blocking manner.

Here's a high-level example using async/await (requires Node.js 7.6+):

async function processContacts(contacts) {
  for (const contact of contacts) {
    // Store a new row in the database (using async/await or Promises)
    await db.storeContact(contact);

    // Send HTTP request to an external API (using async/await or Promises)
    await axios.post('external-api-url', contact);
  }
}

// Assuming you have an array of contacts
const contacts = [...]; // Your array of 5000+ contacts
processContacts(contacts)
  .then(() => console.log('All contacts processed successfully!'))
  .catch((error) => console.error('Error processing contacts:', error));

By using asynchronous I/O operations with async/await or Promises, Node.js will efficiently handle the database and HTTP operations in a non-blocking way, making sure your application remains responsive and performant.