coco process stderr

[jan-swiecki]

I spawn child_process of coco. If there is an error stderr has only one line (manually executed has them more).

Example code:

# index.co
not_working_script(

# coco_test.co
cp = require 'child_process'
proc = cp.spawn 'coco.cmd', ['-c', 'index.co']

proc.stdout.on 'data', (data)->
    process.stdout.write data

proc.stderr.on 'data', (data)->
    process.stderr.write data

proc.on 'exit', (exit_code)~>
    console.log "exit"

$ coco -c index.co
Failed at: index.co
SyntaxError: missing `)CALL` on line 1

$ coco coco_test.co
Failed at: index.co
exit

[satyr]

Running the same thing (with "coco.cmd" → "coco") gives me:

$ coco coco_test.co
Failed at: index.co
exit
SyntaxError: missing `)CALL` on line 2

What's coco.cmd? Is this on Windows?

[jan-swiecki]

Yes, forgot to mention it, sorry.

Windows XP SP3
Node 0.8.1
Coco 0.8.0

When I try to spawn "coco" I get

$ coco coco_test.co
CreateProcessW: The system cannot find the file specified.
exit

And "coco.cmd" somehow works. My windows PATH points to C:\Documents and Settings\LND\Application Data\npm where there are ".cmd" files (e.g. coco and coco.cmd)

btw. in your output shouldn't exit be last?

PS
I get the same problem in Python with subprocess module.

[satyr]

Windows XP SP3

nodejs/node-v0.x-archive#3871 might be related?

btw. in your output shouldn't exit be last?

Probably because Stream#write doesn't immediately flush.

Changing

proc.stderr.on 'data', (data)->
  process.stderr.write data

to

proc.stderr.pipe process.stderr

makes the exit happen last.

[vendethiel]

coco -ce "foo(" > a.txt

SyntaxError: missing ')CALL' on line 1

cat a.txt

(empty)

this also applies when I try to run, say, coco -c $file from a PHP script, I can't get the error message. I have the first line, only "Failed at: $file"

[jan-swiecki]

@satyr
It might be related.

Thanks for clarification about flushing.

@Nami-Doc
And I have this problem in Python too, but you are running Linux, am I right?

btw. > redirects stdout, not stderr. On windows you can do it like this:

coco -ce "foo(" > a.txt 2>&1

[vendethiel]

I'm running windows 7, and the same thing happens on vista.
I'll try coco -ce "foo(" > a.txt 2>&1, but my php script is supposed to read from stderr too.
Edit : Well, it works in the cmd, but exec("coco -c $file 2>&1", $out) isn't working.
Edit : ok, got it working with > a.txt 2>&1 then reading a.txt !

[jan-swiecki]

I know what could be the problem. I have encountered a similar problem with my own program spawning my other program. I did process.exit(0) after some console.log calls, but only FIRST console.log would show! It seems that console.log and process.stdout.write is asynchronous and process.exit(0) doesn't care about the output buffer.

If I executed my other program directly from command line everything was fine.

Removing process.exit(0) fixed my issue.

Related stuff

[jan-swiecki]

Related: [nodejs] Flushing buffers before exiting

http://stackoverflow.com/a/5151569/1637178

[satyr]

Thanks for the links. Can you check if that commit works?

[jan-swiecki]

Yes, but now when I go back to previous version everything is working fine too. I will reboot and try again.

[jan-swiecki]

It seems that your commit doesn't work now in my case. When I switch console.warn('%s\n', it); with fs.writeSync(2, it + '\n'); it works.

Anyways I would wait for @Nami-Doc to test this.

[satyr]

Uh huh:

coco> console.warn
[Function]
function () {
  process.stderr.write(util.format.apply(this, arguments) + '\n');
}

So apparently the console.warn hack the last link gave doesn't work (probably outdated).

[jan-swiecki]

I see. To be honest I didn't focus on the first paragraph. I meant:

process.exit() will terminate node immediately, even if there are still queued writes to stdout

And I didn't test console.warn before, so I'm sorry for the confusion.