I have code executing in a subprocess that is supposed to raise an exception.
I would like to raise the same exception in the main process when the exception is returned from the subprocess (preferably while preserving the stack trace) but I am not sure how to do this.
I capture the stderr from the subprocess just fine but I can't find how to parse it so I get the type of exception. How would I accomplish this?
I am using python 2.7
main method
import subprocess
example=subprocess.Popen(["python","example.py"],
stdout = subprocess.PIPE,
stderr = subprocess.PIPE)
return_obj, return_error = example.communicate()
if return_error:
# replace with error from subprocess
print "Should raise ",NameError('HiThere')
raise TypeError('Wrong type')
subprocess
raise NameError('HiThere')
If all you want is your python code running in a separate process, you should probably not use subprocess. As Serge Ballesta said, subprocess' purpose is to run a different program at the OS level, without particularly caring for what it is - there's nothing to help you properly handle the intricacies of a python interpreter process.
For this kind of purpose, it's probably best to simply import your code and use multiprocessing, which exposes a high-level interface to help you run python code in multiple processes.
Assuming you have a well defined main function on example.py:
from examply import main as example_main
import multiprocessing
pool= multiprocessing.Pool(1)
pool.apply( example_main )
Using this code, both exceptions and return values will be transparently given to your main process.
You can also use Pool.apply_async, if you don't want to block waiting for the result.