In article <[EMAIL PROTECTED]>,
Tom Plunket <[EMAIL PROTECTED]> wrote:
> I'm using subprocess to launch, well, sub-processes, but now I'm
> stumbling due to blocking I/O.
>
> Is there a way for me to know that there's data on a pipe, and possibly
> how much data is there so I can get it? Currently I'm doing this:
>
> process = subprocess.Popen(
> args,
> bufsize=1,
> universal_newlines=True,
> stdout=subprocess.PIPE,
> stderr=subprocess.PIPE)
>
> def ProcessOutput(instream, outstream):
> text = instream.readline()
> if len(text) > 0:
> print >>outstream, text,
> return True
> else:
> return False
I think it would be fair to say that your problem is
not due to blocking I/O, so much as buffered I/O. Since
you don't appear to need to read one line at a time, you
can detect and read data from the file descriptor without
any buffering. Don't mix with buffered I/O, as this will
throw the select off. From memory - better check, since
it has been a while since I wrote anything real like this
(or for that matter much of anything in Python) --
import select
def ProcessOutput(instream, outstream):
fdr = [instream.fileno()]
(r, w, e) = select.select(fdr, [], [], 0.0)
for fd in r:
text = os.read(fd, 4096)
outstream.write(text)
Donn Cave, [EMAIL PROTECTED]
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