thoth@lightning.cis.ufl.edu (Gilligan) (07/30/90)
I'd love to be able to do parallel processing in my X programs, and
so would Dan, but the current Xlib does not cooperate with the sun's
nbio library.
I've posted about this before and I'll post again and again until
someone explains to me why the Xlib can't be made to work with Sun's
-lnbio and -llwp.
I've seen pieces of the code that turn on non-blocking IO and I
assume that it is hosing the nbio. One of these days I'll hack around
that but I don't understand it enough to do it yet.
Xman is the perfect example of the sucky model for "asynchronous
processing". When you want a man page your xman is stuck until it is
finished formatting that page. If you format csh you're in for a long
wait.
I've had to do similar stuff. Once I had a program that wanted to
insert a lot of stuff into a text widget. The ideal model would be to
spawn a lightweight process and print stuff down a pipe which an
AppInput reads and inserts into the text widget.
The reason you have to spawn a process is so you don't have to worry
about filling up the buffer. If your printing process fills its bufer
then you are blocked until the X process reads it off. If I were to
use a Sun lightweight process then I'd be hosed the instant I filled
the buffer. The entire pod would block and the data would never be
read.
If you try to use the nbio library (which would automatically switch
your thread out when you block) then your X stuff doesn't work.
My program was able to fork because I didn't need to modify any of
my main data structures. Only the printed data needed to be passed
back to the main program. If you ever want to modify the main
thread's data (like Xman) you have to use lightweight processes.
Until someone shows me how to modify Xlib I'm stuck in the dark ages
of WorkProcs and
if (count++ >= 1024)
{
count = 0;
while (XtAppPending (app_con))
{
static XEvent xev;
XtAppNextEvent (app_con, &xev);
XtDispatchEvent (&xev);
}
}
Bloody hell. I'm off to try a new hack.
If I am not making sense then send me mail. I'll try to explain
further to anyone who asks.
Hack on . . .
--
( My name's not really Gilligan, It's Robert Forsman, without an `e' )