Re: [libmicrohttpd] Thread Pooling

[Christian Grothoff]

On Wednesday 04 March 2009 10:03:08 pm Richard Alimi wrote:
> Hi Christian,

[lots of stuff not requiring any discussion deleted here]

> It certainly is trickier if load balancing is a target.  I'll first cleanup
> the existing thread pool patch, then consider the second (integration with
> select/epoll) as a second item.
>
> It seems to me there could be some possible steps towards load balancing:
>
> (1) When accepting a new connection, add it to the thread with the fewest
> number of active connections. Connections never move between threads.
>
> (2) Allow connections to move between threads. One simple metric is to try
> to equalize the number of connections per thread.
>
> (3) Allow the library user to influence load balancing to take into account
> the application's processing overhead per request.  I don't currently have
> a good idea for how something like this could be done in a clean way,
> though.
>
> What do you think?

I'd say let's keep it simple: add new connections to the thread with the 
fewest number of active connections.  Given that most will be short-lived and 
most connections will have similar characteristics, I think this should result 
in at least decent load balancing. Moving connections between threads would 
require locking which would then possibly be a bigger bottleneck then what 
would be caused by a possible imbalance. Asking the application for help would 
really complicate the API so that's really not a good idea in my book.

My 2 cents.

Christian