[Python-Dev] Re: PEP 324 (process module) (original) (raw)

Chris McDonough chrism at plope.com
Wed Aug 4 18:46:56 CEST 2004

On Wed, 2004-08-04 at 12:25, Peter Astrand wrote:

> > Why not avoid threads on POSIX systems, and use select instead? My module > > does, although it does not provide an event-like IO interface. If you get > > rid of the threads, then you don't need the workaround code for Linux. > > Doesn't select() effectively busy-wait on "real" files (pipes and file > descriptors obtained via open(), as opposed to network sockets) on most > (all?) UNIXen? At least this has been my finding under Linux.

Yes, but a solution with threads will have problems as well, since read() and friends will return EOF rather than block when you reach the end.

As I've found, if the end of the pipes in that represent the child's stderr/stdout fds are closed in the parent, a select() reading the "other" ends of these pipes will busywaut (at least on Linux). Other than than, I think this select() would be the absolute right thing on POSIX rather than using threads or polling. Is there a way around this problem or is it just a fact of life?

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