On 12/12/05, Joel Reymont
Folks,
I love the Erlang multi-processing experience and think that a lot of the mistakes that I made could be avoided. What I want to have is
1) Processes, aka threads with single-slot in/out mailboxes 2) A facility to keep a list of such processes and send events to them using their process id 3) A socket reader/writer abstraction that communicates with the outside world using using its mailboxes
Probably some other things but I would start with the above. I also want to use STM for this.
One particular thing that bugs me is that I cannot really use TChan for thread mailboxes. I don't think I experienced this problem with Erlang but using a TChan with a logger thread quickly overwhelms the logger and fills the TChan and a lot (hundreds? thousands) of other threads are logging to it. Someone said it's because the scheduler would give ther other threads proportionally more attention.
You could use a bounded TChan. Chans are good because the smooth out "noise".. Ie a sudden surge of messages can be handled without stalling the senders, but sustained heavy traffic will cause a stall (preventing the TChan from growing too big). Here's an untested, off-the-top-of-my-head, implementation.. I may have gotten some names wrong but it should be quite straightforward to write a "real" implementation.. -- may want a newtype here? type BoundedTChan a = (TVar Int, Int, TChan a) -- (current size, max, chan) newBoundedTChan n = do sz <- newTVar 0 ch <- newTChan return (sz,n,ch) writeBoundedTChan (sz,mx,ch) x = do s <- readTVar sz when (s >= mx) retry writeTVar sz (s+1) writeChan ch x readBoundedTChan (sz,mx,ch) = do modifyTVar sz (-1) readTChan ch (s+1) /S -- Sebastian Sylvan +46(0)736-818655 UIN: 44640862