Shutting Down the RTS
I'm almost ready to send in a patch that should fix most of the current issues with the threaded RTS. But I'm stuck at the problem of terminating the RTS in a proper way. According to the GHC manual, a concurrent Haskell program should terminate when the main action terminates. This sounds reasonable and matches the behaviour of C programs on most platforms. In the threaded RTS, this behaviour has never been implemented. We can't simply return from schedule(), because we might no longer be running in the thread of the RTS main() routine. The thread where rts_mainEvalIO was called might be busy executing some foreign code that we know nothing about. (Im)possible solution #1: As soon as the main action terminates, call shutdownHaskellAndExit(). At first, this seems to work fine. But then, shutdownHaskellAndExit() comes along and tries to run finalizers. For every finalizer, the RTS is started back up again using rts_mainEvalIO(), and this time, we really have to exit by returning from rts_mainEvalIO(). Possible solution #2: Forget about running finalizers at program termination and just exit(). In most of the situations where I'd use finalizers, I don't need to run them upon program termination, the OS cleans up after me. Also, the finalizers are not run in the correct order anyway, and there are situations where running them in the wrong order might be worse than not running them at all. And, most of all, solution #2 is easy to implement. Can somebody suggest a third solution, or shall I go for #2 for the time being? Cheers, Wolfgang ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Re: Shutting Down the RTS
An advantage of solution #2 is that the finalizers dont go through and touch all the pages they modify causing them to be loaded into memory if they had been swapped to disk and thrash the page lookup cache on the CPU. The overhead of the RTS in general might drown out these concerns but they are definatly considered important when writing efficient C utilities. John On Mon, Jan 13, 2003 at 12:41:17AM +0100, Wolfgang Thaller wrote: > I'm almost ready to send in a patch that should fix most of the current > issues with the threaded RTS. > But I'm stuck at the problem of terminating the RTS in a proper way. > > According to the GHC manual, a concurrent Haskell program should > terminate when the main action terminates. This sounds reasonable and > matches the behaviour of C programs on most platforms. > > In the threaded RTS, this behaviour has never been implemented. We > can't simply return from schedule(), because we might no longer be > running in the thread of the RTS main() routine. The thread where > rts_mainEvalIO was called might be busy executing some foreign code > that we know nothing about. > > (Im)possible solution #1: As soon as the main action terminates, call > shutdownHaskellAndExit(). At first, this seems to work fine. > But then, shutdownHaskellAndExit() comes along and tries to run > finalizers. For every finalizer, the RTS is started back up again using > rts_mainEvalIO(), and this time, we really have to exit by returning > from rts_mainEvalIO(). > > Possible solution #2: Forget about running finalizers at program > termination and just exit(). > In most of the situations where I'd use finalizers, I don't need to run > them upon program termination, the OS cleans up after me. Also, the > finalizers are not run in the correct order anyway, and there are > situations where running them in the wrong order might be worse than > not running them at all. > And, most of all, solution #2 is easy to implement. > > Can somebody suggest a third solution, or shall I go for #2 for the > time being? > > > Cheers, > > Wolfgang > > ___ > Glasgow-haskell-users mailing list > [EMAIL PROTECTED] > http://www.haskell.org/mailman/listinfo/glasgow-haskell-users > -- --- John Meacham - California Institute of Technology, Alum. - [EMAIL PROTECTED] --- ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Uninitialized UArray - feature or bug?
Hello! This is a little weird: Prelude> :m + Data.Array.Unboxed Prelude Data.Array.Unboxed> let f () = array (1, 5) [] :: UArray Int Int Prelude Data.Array.Unboxed> f () == f () False Are we giving away purity for efficiency? ;) If this behaviour is intended, maybe it should be documented? Maybe it would be a good idea to define default values for types which can be unboxed? Regards, Tom -- .signature: Too many levels of symbolic links ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
Why doesn't this Template Haskell program work?
I compiled the following program with ghc-5.05.20030109
--
import Language.Haskell.THSyntax
main = putStrLn (show $(lift ('a', 'b')))
instance (Lift a, Lift b) => Lift (a,b) where
lift (a,b) = tup [lift a, lift b]
-
and received the following error message
---
ghc --make -fglasgow-exts -package haskell-src -package haskell98
Main.hs -o test
Chasing modules from: Main.hs
Compiling Main ( Main.hs, ./Main.o )
Loading package base ... linking ... done.
Loading package haskell98 ... linking ... done.
Loading package haskell-src ... linking ... done.
ghc-5.05.20030109: panic! (the `impossible' happened, GHC version
5.05.20030109):
nameModule zdfLiftZ2T{-a1dB-}
Please report it as a compiler bug to [EMAIL PROTECTED],
or http://sourceforge.net/projects/ghc/.
--
Why? Because if I compile the following program,
import Language.Haskell.THSyntax
main = putStrLn (show $(tup [lift 'a', lift 'b']))
it works just fine.
Also, is the template-haskell mailing list active?
Sean Seefried
___
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Another question regarding Template Haskell
Would it be possible to write a function "showFun" such that one could write a program f x y = x +y -- say main = putStrLn (show $(showFun f)) and the result of this program would be "f" I don't think it's possible at the moment because one can't reify expressions. Sean Seefried p.s. If I'm posting to the wrong group, I apologise, it's just that template-haskell doesn't seem to be a mail group just yet. I've posted to it and haven't seen any of my postings appear yet. ___ Glasgow-haskell-users mailing list [EMAIL PROTECTED] http://www.haskell.org/mailman/listinfo/glasgow-haskell-users
