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1.0.4 • Public • Published

Child process exec argv

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child-process-exec-argv eases debugging of child process.


Debugging nodejs forked or clusterd child process can sometimes be difficult. For example in visual studio code it almost comes out of the box. You will find you need to change the argsv of your child process - code modifications. It's not recommended for most projects to be framilier with the required code modification.

This is when this module comes in handy, it will do the dirty code modifications for you. Including assigning random ports to child process, while validating that these are free.

Simple usage

The following usage should be enough to most projects.

    const childProcessExecArgv = require('child-process-exec-argv');
    const subprocess = require('child_process').fork('subprocess.js' , [] , {
        execArgv : await childProcessExecArgv.getExecArgv()

If you must have sync result you can use the sync methods, just know that the async method will validate that the random port is valid, while sync method cannot.

    const childProcessExecArgv = require('child-process-exec-argv');
    const subprocess = require('child_process').fork('subprocess.js' , [] , {
        execArgv : childProcessExecArgv.syncGetExecArgv()

Advanced usage

This module come with some customization to enable usage to varity of integrations.

When requiring the main module you will recive a singlton for your convince , you can also you create a custome instance for better encapsulation/customization.

By default this module will identify the current process is being debugged and will request debugging on the child process. You can overide this behavior by:

  • Excuting the main process with child-debugger=disabled.
  • Modifing the singlton property childProcessExecArgv.childDebuggble = false
  • By creating a custome childProcessExecArgv.

Create a custome childProcessExecArgv

    const {ChildProcessExecArgv} = require('child-process-exec-argv');
    const childProcessExecArgv = new ChildProcessExecArgv();
    //For example disable debugging only for this process
    childProcessExecArgv.childDebuggble = false;
    const subprocess = require('child_process').fork('subprocess.js' , [] , {
        execArgv : await childProcessExecArgv.getExecArgv()

How to debug forked process in visual studio code

Altough visual studio code comes with a built in support for identifying child process and attaching to them, in some cases it will not manage the ports correctly.

The following changes will help you gainning child process debugging.

Add to your current process in launch.json the following paramter:

 "autoAttachChildProcesses": true

Take exec argv for this module and forward it to the fork function

    const childProcessExecArgv = require('child-process-exec-argv');
    const subprocess = require('child_process').fork('subprocess.js' , [] , {
        execArgv : await childProcessExecArgv.getExecArgv()

Happy debugging!

Debug with WebStorm

Webstorm is doing a great job with debugging child processes, altough possible to use both we didn't find a reason to use this module while using webstorm.




npm i child-process-exec-argv

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