[Haskell-cafe] Real-time code in Haskell (Was: Can a GC delay TCP connection formation?)

[Felipe Almeida Lessa]

http://hackage.haskell.org/packages/archive/base/4.6.0.0/doc/html/System-Mem.html#v:performGC

On Tue, Nov 27, 2012 at 5:52 PM,  <timothyhobbs at seznam.cz> wrote:
> What triggers GC in haskell?  We obviously aren't using Java's method of GC
> as needed(for good reasons, Java's method is terrible because you get slow
> downs when you need speed the most).  But we should be able to learn
> something from Java and have a gc::IO() method that one could call BEFORE a
> critical region of code...
>
>
> ---------- Původní zpráva ----------
> Od: Mike Meyer <mwm at mired.org>
> Datum: 27. 11. 2012
> Předmět: [Haskell-cafe] Real-time code in Haskell (Was: Can a GC delay TCP
> connection formation?)
>
> On Tue, Nov 27, 2012 at 3:45 AM, Gregory Collins
> <greg at gregorycollins.net> wrote:
>> If you have a hard real-time requirement then a garbage-collected
>> language may not be appropriate for you.
>
> This is a common meme, but frankly, it isn't true. When writing
> real-time code, you just need to make sure that everything that
> happens takes a known maximum amount of time. Then, you can sum up the
> maximums and verify that you do indeed finish in the real-time window
> of the task.
>
> GC is a problem because it's not predictable, and may not have a
> maximum. However, it's no worse than a modern version of the C
> function malloc. Some of those even do garbage collection internally
> before doing an OS call if they're out of memory. The solution is the
> same in both cases - make sure you don't do GC (or call malloc) in the
> critical region. Both require knowing implementation details of
> everything you call, but it isn't impossible, or even particularly
> difficult.
>
> Lazyness, on the other hand ... I haven't thought about. I suspect you
> need to force the evaluation of everything you're going to need before
> you start the critical region, but I wonder if that's enough? Has
> anyone out there investigated this?
>
> Thanks,
> <mike
>
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-- 
Felipe.