Re: revised lightweight dispatcher

[Howard Chu <hyc@symas.com>]

Kurt D. Zeilenga wrote:
> I've committed a revised lightweight dispatcher.
> Aside from various cleanups (no suspend flags),
> the main difference is writers are now spun out
> into separate threads.  Also, readers now spawn
> operation threads instead of performing the
> operation itself.  This is to reduce the clear
> read flag handling.
>
> Initial tests show this revision performs
> reasonably well.

I see it still uses the lazy semaphore code, so the listener thread can 
still be blocked and prevented from runnning the idletimeout checker.

The looping problem I referred to earlier appears to have been 
minimized. I still see one or two extra wakeups on the read event, but 
it doesn't seem to be a runaway condition any more.

Obviously there is still a race condition between the time the listener 
kicks off  the read/write handler and when it goes back to select/epoll. 
If the handler hasn't performed enough I/O on the descriptor yet, the 
event will fire again.

--
 -- Howard Chu
 Chief Architect, Symas Corp.  http://www.symas.com
 Director, Highland Sun        http://highlandsun.com/hyc
 OpenLDAP Core Team            http://www.openldap.org/project/