On Nov 7, 6:54 am, Thomas Christensen <[EMAIL PROTECTED]> wrote: > This issue has been raised a couple of times I am sure. But I have yet > to find a satisfying answer. > > I am reading from a subprocess and this subprocess sometimes hang, in > which case a call to read() call will block indefinite, keeping me from > killing it. > > The folloing sample code illustrates the problem: > > proc = subprocess.Popen(['/usr/bin/foo', '/path/to/some/file'], > stdout=subprocess.PIPE) > output = StringIO.StringIO() > while True: > r = select.select([proc.stdout.fileno()], [], [], 5)[0] > if r: > # NOTE: This will block since it reads until EOF > data = proc.stdout.read() > if not data: > break # EOF from process has been reached > else: > output.write(data) > else: > os.kill(proc.pid, signal.SIGKILL) > proc.wait() > > <Process the output...> > > As the NOTE: comment above suggests the call to read() will block here. > > I see two solutions: > > 1. Read one byte at a time, meaning call read(1). > 2. Read non-blocking. > > I think reading one byte at a time is a waste of CPU, but I cannot find > a way to read non-blocking. > > Is there a way to read non-blocking? Or maybe event a better way in > generel to handle this situation? > > Thanks > > Thomas
As far as I know, you can use '''fctnl''' to make a file handle non- blocking. But : 1. I don't know if it works on standard io 2. If it works in python -- http://mail.python.org/mailman/listinfo/python-list
