Stephen Kennedy reminds us that cooperative threading using generators is an alternative. Two links describe this at a bit more length:

• James Henstridge's post at [www.daa.com.au]
• David Mertz' Charming Python article `Implementing "weightless threads" with Python generators': [www-106.ibm.com]

Advantages:

• Guaranteed to work regardless of underlying thread support
• Much simpler to code and debug, no need for locks, semaphores etc.
• Allows extremely efficient scheduling. Thread creation/deletion overhead is minimal.

Disadvantages:

• Potentially long running or blocking operations (file.read etc) need to be handled specially.

For capturing the output of another process, or other file-based I/O, Danny Milosavljevic proposes using non-blocking I/O. This works like so:

• start the process via popen2.Popen4 (or use any other stuff that uses file descriptors, like pipes, ptys, whatever)
• set the file descriptor to non blocking mode (via fcntl F_SETFL O_NONBLOCK)
• use gtk.input_add to add a handler to be called a) on data or b) on process termination (gtk.gdk.INPUT_READ | gtk.gdk.INPUT_EXCEPTION)
• This handler
  • read()s what it can
  • when reaching EOF that means the process terminated, and you can check the Popen4 object for the exit code
  • when exception IOError with errno EAGAIN is fired, that means currently there is no (more) data available
  • other IOErrors are fatal.

He has an example module available under the LGPL at [traveller.cvs.sourceforge.net] Check out about line 243. You should note he has deprecated this particular piece of code, and is using gobject.io_add_watch instead. The input_add functionality is commented still.