python threading app error to many arguments

Question

What is wrong with this python source code?

import threading
import subprocess as sub

def ben(fil):
    pr = sub.Popen(fil,stdout=sub.PIPE,stderr=sub.PIPE)
    output, errors = pr.communicate()
    print output

theapp = '''blender
            blender-softwaregl'''.split()
print theapp

for u in theapp:
    print u
    tr = threading.Thread(target=ben, args=(u))
    tr.daemon = True
    tr.start()

The error is :

['blender', 'blender-softwaregl']
blender
Exception in thread Thread-1:
Traceback (most recent call last):
  File "/usr/local/lib/python2.7/threading.py", line 551, in __bootstrap_inner
    self.run()
  File "/usr/local/lib/python2.7/threading.py", line 504, in run
    self.__target(*self.__args, **self.__kwargs)
TypeError: ben() takes exactly 1 argument (7 given)

blender-softwaregl
Exception in thread Thread-2:
Traceback (most recent call last):
  File "/usr/local/lib/python2.7/threading.py", line 551, in __bootstrap_inner
    self.run()
  File "/usr/local/lib/python2.7/threading.py", line 504, in run
    self.__target(*self.__args, **self.__kwargs)
TypeError: ben() takes exactly 1 argument (18 given)

This is my problem.What is this error?

 TypeError: ben() takes exactly 1 argument (18 given)

Blckknght · Accepted Answer · 2012-12-18 21:21:53Z

21

The args argument to threading.Thread expects a sequence, but you're providing a string. This is causing it to interpret each letter of the strings as an individual argument, resulting in too many arguments for your target function.

You're very close to having the right code. You just need to fix your tuple syntax by adding a trailing comma in the parenthases:

tr = threading.Thread(target=ben, args=(u,)) # comma makes args into a 1-tuple

answered Dec 18, 2012 at 21:21

Blckknght

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2 Comments

jfs Over a year ago

you could wrap it in a list Thread(target=ben, args=[u]) as an alternative. It might be easier to read though a tuple is more valid semantically.

Cătălin George Feștilă Over a year ago

If i use args=[u] is not working , also if I use args=(u,) seam working but: File "/usr/local/lib/python2.7/subprocess.py", line 1237, in _execute_child <type 'exceptions.AttributeError'>: 'NoneType' object has no attribute 'close' So is need to close the thread ? Do you can help me ?

stamat · Accepted Answer · 2012-12-18 23:27:02Z

0

For some reason it seems that you are passing lists of characters as arguments instead of strings.

I got that cause blender has 7 letters and you got Type error 7 arguments passed. And the blender-softwaregl has 18 letters so you've got Type error for 18 arguments instead of one.

If you want to pass more than one arguments to the subprocess. Popen, try passing the dictionary with the variable name fill and the value list.

def ben(fil):
    pr = sub.Popen(fil,stdout=sub.PIPE,stderr=sub.PIPE)
    output, errors = pr.communicate()
    print output

d = {'fil':['command1', 'command2']}

ben(**d)

One more thing. Why are you opening a Thread if you are opening the subprocess??? A subprocess is a separate process, you dont need the thread part. And your code will work without the thread part, I guess.

edited Dec 18, 2012 at 23:27

answered Dec 18, 2012 at 13:32

stamat

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5 Comments

Cătălin George Feștilă Over a year ago

I don't understand. can you give more infos? You tell me about d and **d[args] . What is the problem ? Why is 18 args when i send just one? I'm a little lost in this. Thank you. regards.

stamat Over a year ago

The d is a variable holding a dictionary, when you put **d['args'] that means you are passing a dictionary as arguments, thats all... But i figured out your problem! Blender has 7 letters blender-softwaregl haz 18 letters I guess you are somehow passing a list of characters as arguments :)

stamat Over a year ago

I was fast to add my answer, so I will fix it. Anyway I was looking int your code and I noticed one more thing...

stamat Over a year ago

You dont need threading at all, just replace tr = threading.Thread(target=ben, args=(u)) tr.daemon = True tr.start() with ben(fil)

Cătălin George Feștilă Over a year ago

I want to use time command to see how the fast is open this binary. This is the reason for using threading. args=(u,) is the solution for.

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