[Haskell-cafe] Bug in parallel GHC runtime?

[Simon Marlow]

Don Stewart wrote:
> Hi,
> 
> Thanks for the bug report.
> This should be filed on the GHC bug tracker,
> 
>     http://hackage.haskell.org/trac/ghc/newticket?type=bug
> 
> And I've forwarded it to the glasgow-haskell-bugs mailing list.

Please try with the 6.8.3 RC we just released.  I fixed a bug that could be 
the cause of this.

http://www.haskell.org/pipermail/glasgow-haskell-users/2008-May/014814.html

Cheers,
	Simon

> 
> kolar:
>> Hello all,
>>
>>  The attached file was compiled by the following command:
>>
>> ghc -O2 --make -threaded ltest1pl.hs -o alall
>>
>> When run in a sequential mode, I get this result:
>> ./alall
>> Starting ...
>> Lst1: 41666666650000
>> Lst2: 41669166700000
>> T1: 0m 1.0e-6s
>> 36
>> End!
>>
>>
>> On the other hand, when run in a threaded mode, I get the following error:
>> ./alall +RTS -N2
>> Starting ...
>> Lst1: 41666666650000
>> Lst2: 41669166700000
>> T1: 0m 0.0s
>> Segmentation fault
>>
>> Is it fault of the GHC runtime, or is it something on my side?
>>
>>
>> My machine: uname -a
>> Linux pc 2.6.24-ARCH #1 SMP PREEMPT Sun Mar 30 10:50:22 CEST 2008 x86_64 
>> Intel(R) Core(TM)2 CPU 6600 @ 2.40GHz GenuineIntel GNU/Linux
>>
>> My ghc: ghc --version
>> The Glorious Glasgow Haskell Compilation System, version 6.8.2
>>
>>
>> Thanks and regards
>>  Dusan
>>
> 
>> --import Control.Concurrent
>> --import Control.Concurrent.MVar
>> import System.Time
>>
>> import Control.Parallel.Strategies
>>
>> --import Data.List (foldl')
>> import qualified Data.ByteString as B
>>
>>
>> sumAllSums [] = 0
>> sumAllSums l@(_:xs) = sumlist 0 l + sumAllSums xs
>>   where  sumlist res [] = res	
>>          sumlist sr  (v:vs) = sumlist (sr+v) vs
>>
>> wlist2wbs [] = B.pack []
>> wlist2wbs l@(_:_) = B.pack $ encode l
>>   where
>>     encode :: Integral a => [Int] -> [a]
>>     encode [] = []
>>     encode (x:xs) = 
>>       if x==0 then 0:0:encode xs
>>       else fromIntegral (x `mod` 256) : fromIntegral (x `div` 256) : encode xs
>>
>> main = do
>>   putStrLn $ "Starting ..."
>>   let lst1 = [0..49999]
>>   let lst2 = [0..50000]
>>   let bs1 = wlist2wbs lst1
>>   let bs2 = wlist2wbs lst2
>>   tm1 <- getClockTime
>>   let (v1:v2:_) = parMap rnf sumAllSums [lst1,lst2]
>>   tm1' <- getClockTime
>>   putStrLn ("Lst1: " ++ show v1)
>>   putStrLn ("Lst2: " ++ show v2)
>>   let tdiff1 = diffClockTimes tm1' tm1
>>   --let tdiff2 = diffClockTimes tm2' tm2
>>   putStrLn $ "T1: " ++ show (tdMin tdiff1) ++ "m " ++ show (fromIntegral(tdSec tdiff1) + fromIntegral(tdPicosec tdiff1)/1e12) ++ "s"
>>   --putStrLn $ "T2: " ++ show (tdMin tdiff2) ++ "m " ++ show (fromIntegral(tdSec tdiff2) + fromIntegral(tdPicosec tdiff2)/1e12) ++ "s"
>>   putStrLn $ show $ {-ibs1 +-} B.index bs1 99999 + B.index bs2 49999 {-((bs1 + fromIntegral (B.index bs2 99999)) :: Integer)-}
>>   putStrLn $ "End!"
>>
>> {-
>> main = do
>>   tm1 <- getClockTime
>>   putStrLn $ "Starting ... "
>>   mv1 <- newEmptyMVar
>>   mv2 <- newEmptyMVar
>>   t1 <- forkIO (putMVar mv1 $! sumAllSums [0..49999])
>>   t2 <- forkIO (putMVar mv2 $!  sumAllSums [1..50000])
>>   v1 <- takeMVar mv1
>>   v2 <- takeMVar mv2
>>   killThread t1
>>   killThread t2
>>   putStrLn $ "Result: " ++ show (v1+v2)
>>   tm2 <- getClockTime
>>   let tdiff = diffClockTimes tm2 tm1
>>   putStrLn $ "End! " ++ show (tdMin tdiff) ++ "m " ++ show (fromIntegral(tdSec tdiff) + fromIntegral(tdPicosec tdiff)/1e12) ++ "s"
>> -}
>>
> 
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> 
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