error Error: listen EADDRINUSE :::5858 when using node debug

[alexklibisz]

I'm using node 6.0.0 and commander ^2.9.0. I'm trying to use the built-in node debugger to inspect at some breakpoints.

Case 1: If I run a script that doesn't use commander, it works:

src/cli/works.js:

var x = 5;
setTimeout(() => {
  debugger;
  console.log('world');
}, 1000);
console.log('hello');

$ node debug src/cli/works.js 
< Debugger listening on port 5858
connecting to 127.0.0.1:5858 ... ok
break in src/cli/works.js:1
> 1 var x = 5;
  2 setTimeout(() => {
  3   debugger;
debug> cont
< hello
break in src/cli/works.js:3
  1 var x = 5;
  2 setTimeout(() => {
> 3   debugger;
  4   console.log('world');
  5 }, 1000);
debug> cont
< world
debug> 

Case 2: If I run my commander script without debug, it also works:

src/cli/cli.js

const
  cli = require('commander'),
  pkg = require('../../package.json');

cli
  .version(pkg.version)
  .command('grid', 'creates grid-style visualization')
  .parse(process.argv);

src/cli/cli-grid.js

debugger;
console.log('grid');

$ node src/cli/cli.js grid
grid

Case 3: But if I run a script with the commander and the debug option, it gives the following error:

$ node debug src/cli/cli.js grid
< Debugger listening on port 5858
connecting to 127.0.0.1:5858 ... ok
break in src/cli/cli.js:1
> 1 const
  2   cli = require('commander'),
  3   pkg = require('../../package.json');
debug> cont
< Error: listen EADDRINUSE :::5858
<     at Object.exports._errnoException (util.js:896:11)
<     at exports._exceptionWithHostPort (util.js:919:20)
<     at Agent.Server._listen2 (net.js:1246:14)
<     at listen (net.js:1282:10)
<     at Agent.Server.listen (net.js:1378:5)
<     at Object.start (_debug_agent.js:21:9)
<     at startup (node.js:85:44)
<     at node.js:444:3
debug> cont
debug> cont
debug> cont

So it seems that there's some sort of issue being cause by using the debugger and commander at the same time. I've searched other issues, but found nothing directly relevant. Thanks in advance.

[rebeccapeltz]

I am experiencing the same problem after an upgrade today.

[remolueoend]

Just ran in the same problem. When using git-style sub-commands, commander.js spawns a new node-process to execute the sub-command which is located in a separate js-file. When spawning a new process, commander.js is copying all original process arguments to the new process, including --debug, --debug-brk etc. (

commander.js/index.js

Line 543 in c6236d9

args = (process.execArgv || []).concat(args);

). That means a new node-process is started trying to listen on port 5858 too and fails because the original node-process is blocking the port.

To fix this, try to debug the sub-command directly:

node --debug my-tool-subcommand.js

Instead of calling the main script using the sub-command as argument:

node --debug my-tool.js subcommand // fails!

[radekk]

It should be added to the documentation, thanks @remolueoend, it works.

[alexklibisz]

If it's considered fixed please feel free to close it. I had forgotten I opened it! :)

[shadowspawn]

This looks like might be a solution on node side?

nodejs/node#5025

bind to random port with --debug-port=0

[shadowspawn]

This issue will be resolved when v3.0.0 is released. Available now as a prerelease. See #1001

[shadowspawn]

If you are using the node inspector for debugging git-style executable (sub)commands using node -inspect et al, the inspector port is incremented by 1 for the spawned subcommand.

Shipped in v3: https://github.com/tj/commander.js/releases/tag/v3.0.0

Thanks to suggestion by @tcf909