repo, cmd: DROP UNEEDED Win path for chcwd & check for '~' homedir by ankostis · Pull Request #529 · gitpython-developers/GitPython

Well, you are quite right - communicate() CAN be trusted.

I did a small experiment of reading a Gbyte, both in PY27 and PY35, and they do not block:

>>> import subprocess as sb
>>> proc=sb.Popen('dd if=/dev/zero bs=1024 count=1000000', bufsize=0, stdin=sb.PIPE, stdout=sb.PIPE, stderr=sb.PIPE)
>>> a,b=proc.communicate()

I don't remember when I got this mistrust for communicate(), maybe when I had tried PY33, or maybe when epxerimenting with interactive processes (like the git.cmd.Git.cat-file persistent command); there the comminicate() is not suitable because it will start consuming streams till the death of the process, but the process is awaiting for more input from python-side before ending, so it's a deadlock.

One or two changes in my windows fixes were under this wrong assumption that communicate() should not be trusted. But mostly I replaced code accessing directly proc.stderr/stdout from the main thread - this is definitely freeze-prone code.