Pm2: Cannot run python script from pm2

[mlb5000]

I'm trying to launch casperjs (a Python launcher script) from pm2 but each time I do I get an error like this

node: ../deps/uv/src/unix/core.c:701: uv__io_stop: Assertion `loop->watchers[w->fd] == w' failed.

Running by hand works fine, just not when launched from pm2. Does pm2 modify the environment in any way that would cause something like this?

[soyuka]

Could you provide a gist or some file example?

Are you running it in fork mode? If not try the -x parameter.

[mlb5000]

yes I was.

pm2 start path/to/casperjs -o casper.out -e casper.out -x --interpreter python -- script.js

[soyuka]

Is casper interpreting python or pm2?
Is casper written in python?

I really don't understand the point, nor has the casper knowledge but this doesn't seems to be a pm2 issue.

[mlb5000]

casperjs in this case is itself a Python script, which is why I though I needed to specify python as the interpreter. The hash bang at the top of the file has /usr/bin/env python. Does that make specifying the interpreter through pm2 redundant or is it still necessary?

[soyuka]

Is it this: http://casperjs.org/?

Could you try running:
pm2 start -o casper.out -e casper.out -x --interpreter python path/to/casperjs script.js

I must say, I find it weird using pm2 with a unit tester script.

[mlb5000]

it does things other than unit testing :). I use it as a more convenient interface to PhantomJS. I'll try that, thanks.

[soyuka]

^^ using python to play with JS running a phantom browser and that forever... Weird.

[soyuka]

263

[romanenko]

We faced the same error

node: ../deps/uv/src/unix/core.c:701: uv__io_stop: Assertion `loop->watchers[w->fd] == w' failed. 

running our nodejs app in fork mode exactly after upgrading from 0.8.2 to 0.8.3. Tested with newer versions — problem exists, before and with 0.8.2 — everything ok.

[Unitech]

Could you try with the latest PM2 version and tell me if it still happens ?

[romanenko]

The problem still exists with pm2 v0.10.7. I'm using node v0.10.25 on Ubuntu 13.04 (GNU/Linux 3.8.0-35-generic x86_64)

[rafahoro]

I had the same issue on OSX (Mavericks), Using NodeJS v0.10.32 and PM2 0.10.8. I've even update to NodeJS v0.11.3 with the same result....but I found a WORKAROUND.

Note: Casperjs (casperjs.org) allows you to write some javascript to test or automate tasks simulating a web-browser. It uses either phantomjs (phantomjs.org) or slimerjs (slimerjs.org) to do the actual HTTP requests, but offer simpler ways to manage flow and fill forms. So you can use casperjs+phantomjs or casperjs+slimerjs. I use it with slimerjs.

I opened the casperjs script and seems like it only read some config and execs other javascript . So I just print the line to be executed and got (replace path_here with real data):
slimerjs /usr/local/lib/node_modules/casperjs/bin/bootstrap.js --casper-path=/usr/local/lib/node_modules/casperjs --cli path_here/appCasper.js
If I run that as is (no pm2), it works well

If I run that with pm2:
pm2 start /usr/local/bin/slimerjs -e err.log -o out.log -- /usr/local/lib/node_modules/casperjs/bin/bootstrap.js --casper-path=/usr/local/lib/node_modules/casperjs --cli path_to/appCasper.js

I get the following error:
"Assertion failed: (loop->watchers[w->fd] == w), function uv__io_stop, file ../deps/uv/src/unix/core.c, line 701." and around 15 instance of my app are created and run at the same time.

The slimerjs shell script do a few things and then runs:
export SLIMER_ARGS="/usr/local/lib/node_modules/casperjs/bin/bootstrap.js --casper-path=/usr/local/lib/node_modules/casperjs --cli /src/appCasper.js"
export __SLIMER_ENV="....... __YOUR_ENV_HERE"
"/usr/local/lib/node_modules/slimerjs/lib/slimer/xulrunner/xulrunner" -app /usr/local/lib/node_modules/slimerjs/lib/slimer/application.ini --profile /tmp/slimerjs.3FQMvM9O -no-remote "/usr/local/lib/node_modules/casperjs/bin/bootstrap.js --casper-path=/usr/local/lib/node_modules/casperjs --cli /src/appCasper.js"

So it actually runs the 'xulrunner'... and so I did:
export __SLIMER_ARGS="/usr/local/lib/node_modules/casperjs/bin/bootstrap.js --casper-path=/usr/local/lib/node_modules/casperjs --cli /src/appCasper.js"
pm2 start /usr/local/lib/node_modules/slimerjs/lib/slimer/xulrunner/xulrunner -x -e err.log -o out.log -- -app /usr/local/lib/node_modules/slimerjs/lib/slimer/application.ini --profile /tmp/slimerjs.3FQMvM9O -no-remote /usr/local/lib/node_modules/casperjs/bin/bootstrap.js --casper-path=/usr/local/lib/node_modules/casperjs --cli /src/appCasper.js

And it works!!!
The only issue I see is that im always using the same "--profile /tmp/slimerjs.3FQMvM9O" this way.... will check how to solve and update here. Also note that __SLIMER_ENV seems to be not necessary fotrthis to work.

So, about the bug itself: I still don't know why it happens but note that:
'/usr/local/bin/casperjs' is a python script that will execute '/usr/local/bin/slimerjs'.
'/usr/local/bin/slimerjs' is a bash script that set's some environment variables and runs '/usr/local/lib/node_modules/slimerjs/lib/slimer/xulrunner/xulrunner'
'/usr/local/lib/node_modules/slimerjs/lib/slimer/xulrunner/xulrunner' is a binary

[kilianc]

same here:
->watchers[w->fd] == w), function uv__io_stop, file ../deps/uv/src/unix/core.c, line 826.

$ cat run.sh
npm run app%
$ pm2 start run.sh -x --interpreter bash

[Downchuck]

Has this bug gotten stuck?

[rafaelgrilli92]

I know this issue is old and already closed, but for those who want to have a CasperJS script running with pm2, here is the working command:

pm2 start your_script.js --interpreter=/usr/lib/node_modules/casperjs/bin/casperjs.js

The interpreter path must be absolute and doesn't matter where your CasperJS is installed, it just needs to point the casperjs.js file.

[Unitech]

ckeckout this article about using pm2 properly with python: https://blog.pm2.io/managing-python-application-with-pm2/

[saifulkhan]

I created a echosystem file echosystem.config.json

{
    "apps": [{
        "name": "app_name",
        "script": "/the/app/path/my_app.py",
        "args": ["-c", "my_config.prod.json"],
        "instances": "1",
        "wait_ready": true,
        "autorestart": false,
        "max_restarts": 5,
        "interpreter" : "/path/to/venv/bin/python",
    }]
}

Run the pm2 service:

$ pm2 start echosystem.config.json
$ pm2 -v
3.2.8