3 Jun
2020
3 Jun
'20
4:42 p.m.
On 6/2/20, Jon Steinhart <jon(a)fourwinds.com> wrote:
Maybe I should explain what I meant by messy. To me, the issue with select is
that in many cases one has to either keep a lot of state somewhere, or live with
long response times while handlers complete. Threads allowed handlers to be
written in the "normal" way with state kept on the stack.
TOPS-10 had a nifty program called ptycon that would allow one to
control multiple login sessions, each on its own pseudo-terminal
device, from a single physical terminal. In 1985 our software tools
group implemented a pseudo-terminal device driver for VMS, and I wrote
a program called ptycon-32. It was multithreaded, with one thread of
control for each pseudo-terminal. The problem is that VMS at the time
didn't have a threads package. I had to roll my own threads by using
the asynchronous system traps (ASTs) delivered by completion of I/O to
the pseudo-terminals. Talk about messy....
-Paul W.