[IPython-dev] ERROR can not use fork(), exec(), dup2() to communicate with child process

[MinRK]

why use execlp instead of subprocess.Popen, which allows capturing stdout,
stderr, etc.?
​

On Thu, Oct 2, 2014 at 4:17 PM, Andy Davidson <Andy at santacruzintegration.com
> wrote:

> Hi
>
>
> I want to write a notebook that receives data from another process. Bellow
> is my python code. It forks a child process and reads the data from the
> child using a pipe. This code works if I run it in python. When I try to
> execute from iPython notebook I get the following error. Any idea what the
> problems is ?
>
>
> If pipes do not work, can I use a socket? The other process would send me
> data by writing, my notebook needs behave like a server.
>
>
> Any comments or suggestions would be greatly appreciated.
>
>
> Thanks
>
>
> Andy
>
>
> P.s. I am running headless on a remote machine and use an ssh tunnel to
> run the notebook from my local browser. My other notebooks works fine
>
>
>
> [ec2-user at ip-172-31-14-107 ~]$ IPYTHON_OPTS="notebook --pylab inline
> --no-browser --port=7000" /root/spark/bin/pyspark
>
> /root/spark/conf/spark-env.sh: line 21: ulimit: open files: cannot modify
> limit: Operation not permitted
>
> [NotebookApp] Using existing profile dir:
> u'/home/ec2-user/.ipython/profile_default'
>
> [NotebookApp] Serving notebooks from /home/ec2-user
>
> [NotebookApp] The IPython Notebook is running at: http://127.0.0.1:7000/
>
> [NotebookApp] Use Control-C to stop this server and shut down all kernels.
>
> [NotebookApp] Using MathJax from CDN:
> http://cdn.mathjax.org/mathjax/latest/MathJax.js
>
> [NotebookApp] Kernel started: 71f07d5c-2db1-465f-9d86-da29f8711a0b
>
> [NotebookApp] Connecting to: tcp://127.0.0.1:54119
>
> [NotebookApp] Connecting to: tcp://127.0.0.1:50649
>
> [NotebookApp] Connecting to: tcp://127.0.0.1:35516
>
> [IPKernelApp] To connect another client to this kernel, use:
>
> [IPKernelApp] --existing kernel-71f07d5c-2db1-465f-9d86-da29f8711a0b.json
>
> Assertion failed: ok (bundled/zeromq/src/mailbox.cpp:79)
>
> [NotebookApp] Kernel 71f07d5c-2db1-465f-9d86-da29f8711a0b failed to
> respond to heartbeat
>
>
>
> import sys
> import os
>
> def child(pipeout):
>     os.dup2(pipeout, sys.stdout.fileno())
>     os.close(pipeout)
>     os.execlp("./test.sh", "abc")
>
>
> def parent():
>     pipein, pipeout = os.pipe()
>     if os.fork() == 0:
>         os.close(pipein)
>         child(pipeout)
>     else:
>         os.close(pipeout)
>         counter = 1
>         pipein = os.fdopen(pipein)
>         while True:
>             json = pipein.readline()[:-1]
>             print 'parent: %s' % (json)
>
> parent()
>
> $ cat test.sh
>
> #!/bin/bash
>
>
> script_name=$0
>
> args=$@
>
> current=`pwd`
>
> echo $script_name $args
>
> echo "XYZ: "$XYZ
>
> echo "PATH: "$PATH
>
> echo "current directory: $current"
>
>
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>
>
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