Gregory P. Smith <g...@krypto.org> added the comment:
A workaround should be pass bufsize=0. There might be performance consequences. That depends on your read patterns and child process. If this is to be supported and fixed, the selectors used in POpen._communicate on the POSIX side presumably don't bother to look at buffered IO objects buffer. https://github.com/python/cpython/blob/master/Lib/subprocess.py#L1959 manually consuming data from the stdout and stderr buffers, if any, before entering that loop is probably a fix. Higher up the chain, should the https://docs.python.org/3/library/selectors.html be enhanced to support emptying the buffer on buffered IO objects? That sounds complicated; probably even infeasible if in text mode. In general it is understood that poll/select type APIs are meant to be used on unbuffered raw binary file objects. ---------- _______________________________________ Python tracker <rep...@bugs.python.org> <https://bugs.python.org/issue41406> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: https://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
