[Lazarus] LNet component Event vs thread ? faster or more reliable?

[Aleš Katona]

Dňa Št, 2008-08-28 o 14:41 +0800, davy zhang napísal:
> I know there are bunch of defects of thread programing and not every
> one like to use it
> 
> but I am still wondering the real efficiency of these two model
> 
> if we use multi-core cpu,  which one is faster, or it just depends on
> the compiler's optimization~


Yes, lNet by default wouldn't use multiple cores but in most cases this
is ok (you don't want to use all cores on just networking events watch).
If you want to make a "really efficient" high-end server tho, try out
the trunk version. I added a TLThreadedEventer which enables you to
specify # of threads which will be used to watch sockets. The eventer
will then fill up those threads with "subeventer" as the sockets come
in. You need to know what you're doing tho, as each callback then gets
executed in its thread!

So in the end, say you specified 200 threads and got 2000 sockets, you
end up with 10 sockets per thread being watched (more or less in a
blocking manner) for events.

This eventer however is really only useful for corner cases like
slashdot effect surviving web servers (note that YOU need to use threads
to handle requests too to make use of cores. Say you forward the request
to PHP via fastcgi, you should do it in ADDITIONAL thread so that the
event-watch threads are independent of the processing).

So.. it's always a choice, having 1 thread per socket would constitute a
huge bottleneck because of scheduling with 10k+ sockets, and having too
many sockets per thread you end up serializing the events to it doesn't
keep up. Best is to find the right balance.

Ales