[Haskell-cafe] GC [Is Haskell a Good Choice for Web Applications?]

[John Lask]

for what its worth, I second this suggestion.

----- Original Message ----- 
From: "Andrew Coppin" <andrewcoppin at btinternet.com>
To: <haskell-cafe at haskell.org>
Sent: Friday, May 08, 2009 6:01 AM
Subject: [Haskell-cafe] GC [Is Haskell a Good Choice for Web Applications?]


> Simon Marlow wrote:
>> http://hackage.haskell.org/trac/ghc/ticket/698
> 
> I presume that the reason for this is to avoid handing memory back only 
> to immediately need it again? (I.e., we don't want to be constantly 
> asking the OS to allocate and deallocate memory. Allocate it once and 
> then let the RTS handle it.)
> 
> How hard would it be to add a function to ask the RTS to shrink the 
> allocated memory? E.g., you do something that you know consumes lots of 
> RAM, you finish doing it, you know that your live set has probably gone 
> way down now, so you ask the RTS to release some RAM if possible. Would 
> that be difficult?
> 
> (I might be talking moonshine, but isn't the parallel GC based around a 
> block-structured heap? Does that affect the difficulty of the problem 
> one way or the other?)
> 
> We already have System.Mem, which currently contains a single function 
> to "suggest" to the RTS that right now might be a good moment to perform 
> some GC. I'd like to see some other functions added here - suggesting to 
> the RTS that it should have a go at shrinking RAM usage is one, but it 
> would be nice to at least be able to query how much RAM is allocated 
> too. (I presume finding out how much we've allocated from the OS is 
> fairly easy; finding out how much is live data is presumably far 
> harder...) Maybe access to various interesting GC information - I don't 
> know if the RTS actually records this stuff when not built for profiling 
> though. (?)
> 
> Just my thoughts... :-)
> 
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