Alternatives to Python Popen.communicate() memory limitations?

Question

I have the following chunk of Python code (running v2.7) that results in MemoryError exceptions being thrown when I work with large (several GB) files:

Answer 1

I think I found a solution:

myProcess = Popen(myCmd, shell=True, stdout=PIPE, stderr=PIPE)
for ln in myProcess.stdout:
    sys.stdout.write(ln)
for ln in myProcess.stderr:
    sys.stderr.write(ln)

This seems to get my memory usage down enough to get through the task.

Update

I have recently found a more flexible way of handing data streams in Python, using threads. It's interesting that Python is so poor at something that shell scripts can do so easily!