On Wed, Aug 22, 2012 at 1:40 PM, Dennis Jacobfeuerborn
<[email protected]> wrote:
> I was thinking about something like that but the issue is that this really
> only works when you don't do any actual blocking work. I may be able to get
> around the sleep() but then I have to fetch the URL or do some other work
> that might block for a while so the get() trick doesn't work.
At a lower level, it is possible to poll on both the pipe and the
socket simultaneously. At this point though you might want to start
looking at an asynchronous or event-driven framework like twisted or
gevent.
> Also the child process might not be able to deal with such an exit command at
> all for one reason or another so the only safe way to get rid of it is for
> the parent to kill it.
I think you mean that it is the most "reliable" way. In general, the
only "safe" way to cause a process to exit is the cooperative
approach, because it may otherwise leave external resources such as
file data in an unexpected state that could cause problems later.
> The better option would be to not use a shared queue for communication and
> instead use only dedicated pipes/queues for each child process but the
> doesn't seem to be a way to wait for a message from multiple queues/pipes. If
> that were the case then I could simply kill the child and get rid of the
> respective pipes/queues without affecting the other processes or
> communication channels.
Assuming that you're using a Unix system:
from select import select
while True:
ready, _, _ = select(pipes, [], [], timeout)
if not ready:
# process timeout
else:
for pipe in ready:
message = pipe.get()
# process message
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