andrewcoppin: > Spencer Janssen wrote: > >On Sun, Jan 06, 2008 at 11:30:53AM +0000, Andrew Coppin wrote: > > > >>Just a couple of things I was wondering about... > >> > >>1. Is there some way to assign a "priority" to Haskell threads? (The > >>behaviour I'd like is that high priority threads always run first, and > >>low priority threads potentially never run at all unless there's an > >>available processor which is completely idle.) > >> > > > >Not in the current system. It is not clear that thread priorities are so > >nice > >anyway (see 'priority inversion' on Wikipedia, for example). > > > > Well, I was thinking more of using them for two things. One is for > speculative work (i.e., doing work which we might need later - but don't > bother unless there's cores going spare). The other is for working on > entirely independent tasks - I don't see how inversion can happen when > one thread is solving problem X and another is solving problem Y. But > sure, it certainly adds more complexity to have priority levels. > > [I can also imagine situations where you might want to assign 80% CPU to > one thing, and 20% CPU to the other - but that really does sound hard to > implement...] > > >>2. I have a situation where I have a thread generating some data and > >>putting it into a mutable array, and another thread trying to read that > >>data. Is there a way I can make the reader thread block if it tries to > >>read a cell that hasn't been computed yet, but not introduce too much > >>overhead for cells that have been filled in? > >> > > > >I'd probably use an Array of TMVars, they should be faster than MVars when > >multiple threads are reading simultaneously. > > > > Mmm, OK. I'll try that. (I wasn't actually aware that STM is working > yet...)
It works, and has done so for a couple of years now. It's used in production systems. Where'd you hear otherwise? -- Don _______________________________________________ Haskell-Cafe mailing list Haskell-Cafe@haskell.org http://www.haskell.org/mailman/listinfo/haskell-cafe
