Blog

Constructing Deep Recurrent Neural Networks for Complex Sequential Data Modelling

Adam23172 Rzymowski23172

August 6, 2025
3 minutes
Download
‌

Introduction

Deep Recurrent Neural Networks (DRNNs) is a powerful evolution of the standard Recurrent Neural Network (RNN) architecture.

The event loop is a core feature of the JavaScript runtime in Node.js, implemented through libuv — a high-performance, event-driven I/O library written in C. At its core, the event loop is simply a semi-infinite while loop that executes a series of operations in a specific sequence, and exits only under defined conditions.

In talking about how the event loop works, it is first important to understand the role of libuv because its core job in the node runtime is to provide the event loop, as well as callback-based notifications of I/O and other activities. It implements the event loop used in Node like this; in pseudocode:

import { readFile } from ‘node:fs’;

readFile(‘./file.txt’, (err, data) => {
    if (err) throw err;
    console.log(“File read successfully”);
});

When an async method, like readFile() in this case, is called, its execution is deferred to one of 2 places:

  1. The Operating System (OS) kernel. Since most modern OSes are multi-threaded, they can handle these operations in the background, and importantly off the JavaScript main thread. Async operations from Node modules like net, http/https, tls, stdin/out/error etc., are handled in the kernel.
  2. A thread pool managed by libuv. Async operations from the fs module or dns.lookup() etc., are handled in the thread pool

In line 2 of the pseudocode above where the event loop gets the next event, they are usually sourced from one of these 2 places. This is referred to as I/O polling and is the crux of the poll phase of the event loop. Some examples of such events are: a file is ready for writing; a socket has data ready to be read, a timer has timed out etc.

‌

What happens after the event loop hands off an async operation for processing?

The default behavior of the event loop will be to wait or more technically, to sleep (block) at the poll phase of the loop. In the readFile code above, when the operation is handed off to libuv’s thread pool, the event loop will wait at the poll phase until the file has been read completely, before executing the callback. However, there are exceptions to this behavior and we will now look at these exceptions, using the different phases of the event loop.

Tags: