Fri, Mar 02, 2012 at 07:34:41PM -0500, Joey Adams wrote > On Fri, Mar 2, 2012 at 3:04 PM, Alexander V Vershilov > <alexander.vershi...@gmail.com> wrote: > > Hello, Paul. > > > > It seems you should not use 3 threads, but run in a data-driven behaviour > > with > > one thread per client. > > I don't think this will work for Paul's situation. He needs to be > able to send notifications to clients. This means sending to the > client even when the client has nothing to say at the moment. > > I've been grappling with the same problem. See: > > http://www.haskell.org/pipermail/haskell-cafe/2012-January/098495.html > > The discussion was recently summed up in Parallel Haskell Digest 8 > (scroll down to "How to make asynchronous I/O composable and safe?"): > > http://www.well-typed.com/blog/64 > > To try to address this problem, I wrote a module called stm-channelize: > > http://hackage.haskell.org/package/stm-channelize > > However, I did not end up using it. I would point you to the source > of my channelize function, but I think it's more complicated than it > needs to be. > > I, for one, would recommend a three-thread approach. That is, for > each client, you basically have: > > * A thread for receiving > > * A thread for sending > > * A main thread that waits for the other two threads, and kills them > when one of them finishes or dies. > > I'll try to put together a simple chat server example, like the one I > wrote for stm-channelize. > > -Joey
Yes, there is no way to use only one thread for such a case, but conduit aproach seems quite easy and take care about resources. Recently I wrote a question about such a situation [1] and it simplification [1] http://www.haskell.org/pipermail/haskell-cafe/2012-February/099770.html I've used smth like stm-channelize approach to make "virtual socket" when there was many clients on one connection. I can check stm-channelize more precietly and write if my aproach has usefull idea for that case. -- Alexander Vershilov.
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