stdout of child process as an input of another thread in Python?

[dieter]

Kevin Peterson <qh.resu01 at gmail.com> writes:

> I want to use the stdout of child process as an input of another thread, but some how I am not able to read the stdout.  Using Popen I have created a child process and stdout of it I have redirected to PIPE (because I don't want that to be printed on with my main process).  Now using this statement,"Line=Proc.stdout.readline()" I want to read stdout of child process and I have to do operation on that. but somehow i am not able to read from stdout of child process. 
>
> Following is the code snapshot - 
>
>     Proc = Popen(["python.exe","filename.py"],stdout=PIPE)
>     
>     while True:
>                 Line = Proc.stdout.readline()
>                 print Line
>
> Here,
> Filename.py(Child process) is continuously printing "Hello World!!" in place of reading stdout of child process. 

Your description is not sufficiently clear:

  If "filename.py" is your child process, why should it read the stdout
  of the child process (i.e. itself).

I suggest, you describe what "filename.py" (your child) does
and what behavior you observe for the parent.