[Haskell-cafe] Re: Thread pool in GHC

[genneth]

Yes, but AFAIK, threads in Haskell are exceedingly lightweight, as
they are only primitives for concurrency. To be perfectly honest, I've
found that my solution is completely useless in practise. I made up
the solution cos I reconned that tweaking GHC runtime heap size would
be harder than making a threadpool (it isn't). Basically, all the
usual reasons for using a threadpool just don't apply in Haskell.

Gen

On 9/6/05, Dinh Tien Tuan Anh <tuananhbirm at hotmail.com> wrote:
> 
> Does it mean that the thread pool will "LAUNCH" new thread as long as the
> thread count does not exceed a maximum number ?
> If it does launch the new thread, then the idea of thread reuse is
> completely ignored.
> My program creates and kills at most 5 threads at a time, but this process
> repeated for an infinite times, so thread reuse would improve the
> performance by getting of the overhead of creating new thread.
> 
> TuanAnh
> 
> >From: genneth <genneth at gmail.com>
> >To: Dinh Tien Tuan Anh <tuananhbirm at hotmail.com>
> >CC: haskell-cafe at haskell.org
> >Subject: Re: [Haskell-cafe] Re: Thread pool in GHC
> >Date: Tue, 6 Sep 2005 10:25:15 +0800
> >
> >I think it would go back to the pool. The finally clause means that
> >even if the thread dies from an exception (which, AFAIK, is how kills
> >are modelled), the thread count would be restored.
> >
> >Gen
> >
> >On 9/6/05, Dinh Tien Tuan Anh <tuananhbirm at hotmail.com> wrote:
> > >
> > > Its probably too long to bring back this topic, but i have a small
> >question.
> > >
> > > If some threads may never terminate and have to be killed by killThread,
> >are
> > > they going back to the pool, or we need some twist to force them.
> > >
> > > Thanks a lot
> > > TuanAnh
> > >
> > > >From: genneth <genneth at gmail.com>
> > > >To: haskell-cafe at haskell.org
> > > >Subject: [Haskell-cafe] Re: Thread pool in GHC
> > > >Date: Thu, 4 Aug 2005 16:47:56 +0000 (UTC)
> > > >
> > > >Dinh Tien Tuan Anh <tuananhbirm <at> hotmail.com> writes:
> > > >
> > > > >
> > > > >
> > > > >   Can thread pool be implemented in GHC ?
> > > > >
> > > > > I have a program that is currently using about 12-15 threads (launch
> >and
> > > > > kill for infinite times) and when running, especially after Ctrl-C,
> >my
> > > > > computer got freezed up. And if i ran it several times, the "Stack
> > > > > overflows" occurs.
> > > >
> > > >I made the following a while back. Maybe it's useful...
> > > >
> > > >limitedThreadsWithChannelMapM :: Integer -> (a -> IO b) -> [a] -> IO
> >[MVar
> > > >b]
> > > >limitedThreadsWithChannelMapM lim ioaction x = do
> > > >     threadpoolcounter <- atomically ( newTVar 0 )
> > > >     mapM (throttledFork threadpoolcounter . ioaction) x
> > > >     where
> > > >         throttledFork poolcount io = do
> > > >             atomically ( do
> > > >                 prev <- readTVar poolcount
> > > >                 if prev >= lim then
> > > >                     retry
> > > >                     else writeTVar poolcount (prev+1) )
> > > >             mvar <- newEmptyMVar
> > > >             forkIO(
> > > >                 finally
> > > >                     (io >>= putMVar mvar)
> > > >                     (atomically ( readTVar poolcount >>= writeTVar
> > > >poolcount .
> > > >(subtract 1) ) ) )
> > > >             return mvar
> > > >
> > > > >
> > > > > Cheers
> > > > > TuanAnh
> > > > >
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