Async child process node

1. How does NodeJS handle child processes?
2. What is the difference between child_process and spawn?
3. How does node js support asynchronous processes?
4. How many child processes are there in node JS?
5. Does wait () wait for all child processes?
6. What happens if wait () is called by a process with no children?
7. What is the difference between exit and close in Node child_process?
8. What is the difference between sync and async in Nodejs?
9. What is async vs sync?
10. Can we use await without async?
11. How does Node.js handle memory?
12. How does Node.js works internally?
13. How does Node.js prevent blocking code?
14. How to avoid memory leak in nodejs?
15. What makes node JS faster?
16. How is node js so fast?

How does NodeJS handle child processes?

Usually, Node. js allows single-threaded, non-blocking performance but running a single thread in a CPU cannot handle increasing workload hence the child_process module can be used to spawn child processes. The child processes communicate with each other using a built-in messaging system.

What is the difference between child_process and spawn?

spawn is best used to when you want the child process to return a large amount of data to Node - image processing, reading binary data etc. child_process. spawn is "asynchronously asynchronous", meaning it starts sending back data from the child process in a stream as soon as the child process starts executing.

How does node js support asynchronous processes?

NodeJS is an asynchronous event-driven JavaScript runtime environment designed to build scalable network applications. Asynchronous here refers to all those functions in JavaScript that are processed in the background without blocking any other request.

How many child processes are there in node JS?

There are four different ways to create a child process in Node: spawn() , fork() , exec() , and execFile() . We're going to see the differences between these four functions and when to use each.

Does wait () wait for all child processes?

wait waits for a child process to terminate, and returns that child process's pid . On error (eg when there are no child processes), -1 is returned. So, basically, the code keeps waiting for child processes to finish, until the wait ing errors out, and then you know they are all finished.

What happens if wait () is called by a process with no children?

A call to wait() blocks the calling process until one of its child processes exits or a signal is received. After child process terminates, parent continues its execution after wait system call instruction. Child process may terminate due to any of these: It calls exit();

What is the difference between exit and close in Node child_process?

the short version is, 'exit' emits when the child exits but the stdio are not yet closed. 'close' emits when the child has exited and its stdios are closed.

What is the difference between sync and async in Nodejs?

Sync is single-thread, so only one operation or program will run at a time. Async is non-blocking, which means it will send multiple requests to a server. Sync is blocking — it will only send the server one request at a time and will wait for that request to be answered by the server.

What is async vs sync?

Synchronous tasks happen in order—you must complete the current task before moving on to the next. Asynchronous tasks are executed in any order or even at once.

Can we use await without async?

You can use the await keyword on its own (outside of an async function) at the top level of a module. This means that modules with child modules that use await will wait for the child modules to execute before they themselves run, all while not blocking other child modules from loading.

How does Node.js handle memory?

Memory Management in Node.

Memory management provides ways to dynamically allocate memory chunks for programs when they request it, and free them when they are no longer needed – so that they can be reused. Application-level memory management can be manual or automatic.

How does Node.js works internally?

Node JS Web Server internally maintains a Limited Thread pool to provide services to the Client Requests. Node JS Web Server receives those requests and places them into a Queue. It is known as “Event Queue”. Node JS Web Server internally has a Component, known as “Event Loop”.

How does Node.js prevent blocking code?

Node. js is a cross-platform JavaScript runtime environment that helps to execute and implement server-side programs. Node is assumed to prevent blocking code by using a single-threaded event loop.

How to avoid memory leak in nodejs?

Avoid Accidental Globals

This could be the result of a typo and could lead to a memory leak. Another way could be when assigning a variable to this within a function in the global scope. To avoid issues like this, always write JavaScript in strict mode using the 'use strict'; annotation at the top of your JS file.

What makes node JS faster?

Take a look at a few aspects that help figure out why Node. js is so fast. Node. js is single-threaded and asynchronous: this means that all I/O activity does not interfere with other processes, and it is possible to send emails, read and write files, query databases, and so on, all at the same time.

How is node js so fast?

The virtual machine can take the source code to compile it into the machine code at runtime. What it means is that all the “hot” functions that get called often than not can be compiled to the machine code thus boosting the execution speed.