In Node.js, it is common to use child processes to perform computationally intensive tasks or run external programs asynchronously. When working with child processes, you may encounter the need to serialize and deserialize objects between the parent and child processes. This can be useful when you want to pass complex data structures or objects from one process to another.

In this blog post, we will explore how to serialize and deserialize objects between parent and child processes in Node.js.

Table of Contents

1. Understanding Serialization and Deserialization
2. Using JSON.stringify and JSON.parse
3. Using the Node.js built-in ‘util’ module
4. Performance Considerations
5. Conclusion

Understanding Serialization and Deserialization

Serialization is the process of converting an object into a format that can be stored, transmitted, or reconstructed later. Deserialization, on the other hand, is the opposite process of converting the serialized data back into an object.

In the context of Node.js child processes, serialization is necessary because objects cannot be directly passed between parent and child processes. Instead, the objects need to be converted into a format that can be transmitted, such as JSON or a binary format.

Using JSON.stringify and JSON.parse

The simplest way to serialize and deserialize objects in Node.js is by using the JSON.stringify and JSON.parse methods. These methods allow you to convert JavaScript objects to a JSON string and vice versa.

Let’s see an example of serializing an object in the parent process and deserializing it in the child process:

// Parent process
const { fork } = require('child_process');
const child = fork('child.js');
const obj = { name: "John", age: 30 };

const serializedObj = JSON.stringify(obj);
child.send(serializedObj);

// Child process (child.js)
process.on('message', (serializedObj) => {
  const obj = JSON.parse(serializedObj);
  console.log(obj);
});

In this example, the obj object is serialized using JSON.stringify in the parent process and sent to the child process using child.send. In the child process, the serialized object is received via process.on('message') and deserialized using JSON.parse.

Using the Node.js built-in ‘util’ module

Node.js also provides the util module, which includes functions for serializing and deserializing objects.

// Parent process
const { fork } = require('child_process');
const child = fork('child.js');
const obj = { name: "John", age: 30 };

const serializedObj = require('util').inspect(obj);
child.send(serializedObj);

// Child process (child.js)
process.on('message', (serializedObj) => {
  const obj = eval(`(${serializedObj})`);
  console.log(obj);
});

In this example, the obj object is serialized using util.inspect in the parent process and sent to the child process. In the child process, the serialized object is received via process.on('message') and deserialized using eval.

Performance Considerations

When it comes to performance, using JSON serialization is generally faster compared to the util module approach. However, the util module provides more flexibility and can handle circular references and complex object structures.

Before choosing a serialization method, consider your specific use case and performance requirements. If performance is critical and the objects you need to serialize do not have circular references or complex structures, using JSON serialization is recommended.

Conclusion

Serializing and deserializing objects between parent and child processes in Node.js is essential when passing complex data structures or objects. In this blog post, we explored two common methods: using JSON.stringify and JSON.parse, and the util module. Consider your specific use case and performance requirements to choose the most suitable method for your application.

Remember to serialize objects before sending them between processes and deserialize them upon receiving to ensure proper communication and data integrity.

#Node.js #ChildProcesses