CODEWITHSUNDEEP
pythonmultithreadingpython-3.x
Kudzu
Kudzu

Reputation: 3638

Multithreading attempt using Python 3.2.2: "AttributeError: 'str' object has no attribute '_initialized'"

I'm running into a problem with the following Python 3.2.2 code. The code is an attempt to do some timing tests of another application I'm testing. The idea is to have another script (of any variety) get passed into the timer program and make some changes to the environment. That script should run in a separate thread, so that I can start timing from the start of the script instead of the end. The rest of this script times the application's reaction to that script. I've attempted to draw from the threading module documentation to create this, and I'm confident that I've read it thoroughly, but I'm consistently running into the following error using this code:

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "C:\Python32\lib\threading.py", line 669, in start
    if not self._initialized:
AttributeError: 'str' object has no attribute '_initialized'

Here's the thread class definition.

import threading, ...

class AsyncScript(threading.Thread):
    def __init__(self, s):
        self.script = s
    def run(self):
        print ("Beginning script...")
        try:
            os.system("cmd /k " + self.script)
        except:
            sys.exit("Error running script " + self.script)

This is called elsewhere in the script by AsyncScript.start(options.script), where the options class contains the options passed into the script (using the argparse module.)

Any ideas about what I might be doing wrong here?

Okay, an update. The following (stripped-down) version of the code DOES work, and I'm honestly not sure why -- I don't see the difference.

import threading

class AsyncScript(threading.Thread):
    def __init__(self, s):
        threading.Thread.__init__(self)
        self.script = s
    def run(self):
        print("This would run script " + self.script)

AsyncScript("sample script path string").start()

Output is, appropriately,

This would run script sample script path string

Aside from the inclusion of threading.Thread.__init__(self), which I had previously included in earlier versions of this code without success, I'm not really sure what's different here. What am I missing?

Upvotes: 0

Views: 3406

Answers (3)

jfs
jfs

Reputation: 414285

You don't need to use threads if you run the script in a separate process anyway. Use subprocess instead of os.system().

You don't need to subclass Thread to create a thread:

Thread(target=func, args=func_args).start()

I'm not really sure what's different here. What am I missing?

There are two differences:

  1. AsyncScript.start(options.script) vs. AsyncScript(options.script).start().

    AsyncScript is a class object. AsyncScript(options.script) is an instance of that class.

    AsyncScript.start(options.script) calls an unbound .start method. It expects its first argument to be an AsyncScript instance not a string options.script. The correct way to call a method is obj.method(). In your case obj = AsyncScript(options.script).

  2. Presense of threading.Thread.__init__(self) in the AsyncScript.__init__() method.

    If you don't call threading.Thread.__init__(self) then Thread's attributes such as _initialized are not created/defined.

Upvotes: 0

user395760
user395760

Reputation:

This is called elsewhere in the script by AsyncScript.start(options.script)

That invokation is wrong. You're calling threading.Thread's nullary (no arguments - not counting self) start method with your script string as self, instead of instanciating your AsyncScript class (passing the string to __init__) and calling the resulting thread object's .start() method. Obviously, a string is not a thread, so the threading code fails when you give it one as self. It should probably be AsyncScript(options.script).start()

Upvotes: 1

agudulin
agudulin

Reputation: 259

self.script isn't initialize in your , but you've got self.s - try to use it

Upvotes: 0

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