为什么我的Haskell程序使用'par'不是';没有产生任何火花?
我正在尝试使用线程编译以下程序:为什么我的Haskell程序使用'par'不是';没有产生任何火花?,haskell,parallel-processing,Haskell,Parallel Processing,我正在尝试使用线程编译以下程序: import qualified Data.Vector.Unboxed as UV passes = UV.fromList [1..1000000] :: UV.Vector Int vector = UV.fromList [1..100] :: UV.Vector Double vectors = x `par` y `par` z `par` w `pseq` (x,y,z,w) where x = UV.foldr' (const (UV.m
import qualified Data.Vector.Unboxed as UV
passes = UV.fromList [1..1000000] :: UV.Vector Int
vector = UV.fromList [1..100] :: UV.Vector Double
vectors = x `par` y `par` z `par` w `pseq` (x,y,z,w) where
x = UV.foldr' (const (UV.map (+1))) vector passes
y = UV.foldr' (const (UV.map (+2))) vector passes
z = UV.foldr' (const (UV.map (+3))) vector passes
w = UV.foldr' (const (UV.map (+4))) vector passes
main = print vectors
但它看起来不像是并行执行的,因为它与N1
或N4
的执行时间几乎相同
vh:haskell apple1$ ghc -fforce-recomp -threaded -O2 bench.hs -o bench; time ./bench +RTS -s -N4
[1 of 1] Compiling Main ( bench.hs, bench.o )
Linking bench ...
(fromList [1000001.0,1000002.0,1000003.0,1000004.0,1000005.0,1000006.0,1000007.0,1000008.0,1000009.0,1000010.0,1000011.0,1000012.0,1000013.0,1000014.0,1000015.0,1000016.0,1000017.0,1000018.0,1000019.0,1000020.0,1000021.0,1000022.0,1000023.0,1000024.0,1000025.0,1000026.0,1000027.0,1000028.0,1000029.0,1000030.0,1000031.0,1000032.0,1000033.0,1000034.0,1000035.0,1000036.0,1000037.0,1000038.0,1000039.0,1000040.0,1000041.0,1000042.0,1000043.0,1000044.0,1000045.0,1000046.0,1000047.0,1000048.0,1000049.0,1000050.0,1000051.0,1000052.0,1000053.0,1000054.0,1000055.0,1000056.0,1000057.0,1000058.0,1000059.0,1000060.0,1000061.0,1000062.0,1000063.0,1000064.0,1000065.0,1000066.0,1000067.0,1000068.0,1000069.0,1000070.0,1000071.0,1000072.0,1000073.0,1000074.0,1000075.0,1000076.0,1000077.0,1000078.0,1000079.0,1000080.0,1000081.0,1000082.0,1000083.0,1000084.0,1000085.0,1000086.0,1000087.0,1000088.0,1000089.0,1000090.0,1000091.0,1000092.0,1000093.0,1000094.0,1000095.0,1000096.0,1000097.0,1000098.0,1000099.0,1000100.0],fromList [2000001.0,2000002.0,2000003.0,2000004.0,2000005.0,2000006.0,2000007.0,2000008.0,2000009.0,2000010.0,2000011.0,2000012.0,2000013.0,2000014.0,2000015.0,2000016.0,2000017.0,2000018.0,2000019.0,2000020.0,2000021.0,2000022.0,2000023.0,2000024.0,2000025.0,2000026.0,2000027.0,2000028.0,2000029.0,2000030.0,2000031.0,2000032.0,2000033.0,2000034.0,2000035.0,2000036.0,2000037.0,2000038.0,2000039.0,2000040.0,2000041.0,2000042.0,2000043.0,2000044.0,2000045.0,2000046.0,2000047.0,2000048.0,2000049.0,2000050.0,2000051.0,2000052.0,2000053.0,2000054.0,2000055.0,2000056.0,2000057.0,2000058.0,2000059.0,2000060.0,2000061.0,2000062.0,2000063.0,2000064.0,2000065.0,2000066.0,2000067.0,2000068.0,2000069.0,2000070.0,2000071.0,2000072.0,2000073.0,2000074.0,2000075.0,2000076.0,2000077.0,2000078.0,2000079.0,2000080.0,2000081.0,2000082.0,2000083.0,2000084.0,2000085.0,2000086.0,2000087.0,2000088.0,2000089.0,2000090.0,2000091.0,2000092.0,2000093.0,2000094.0,2000095.0,2000096.0,2000097.0,2000098.0,2000099.0,2000100.0],fromList [3000001.0,3000002.0,3000003.0,3000004.0,3000005.0,3000006.0,3000007.0,3000008.0,3000009.0,3000010.0,3000011.0,3000012.0,3000013.0,3000014.0,3000015.0,3000016.0,3000017.0,3000018.0,3000019.0,3000020.0,3000021.0,3000022.0,3000023.0,3000024.0,3000025.0,3000026.0,3000027.0,3000028.0,3000029.0,3000030.0,3000031.0,3000032.0,3000033.0,3000034.0,3000035.0,3000036.0,3000037.0,3000038.0,3000039.0,3000040.0,3000041.0,3000042.0,3000043.0,3000044.0,3000045.0,3000046.0,3000047.0,3000048.0,3000049.0,3000050.0,3000051.0,3000052.0,3000053.0,3000054.0,3000055.0,3000056.0,3000057.0,3000058.0,3000059.0,3000060.0,3000061.0,3000062.0,3000063.0,3000064.0,3000065.0,3000066.0,3000067.0,3000068.0,3000069.0,3000070.0,3000071.0,3000072.0,3000073.0,3000074.0,3000075.0,3000076.0,3000077.0,3000078.0,3000079.0,3000080.0,3000081.0,3000082.0,3000083.0,3000084.0,3000085.0,3000086.0,3000087.0,3000088.0,3000089.0,3000090.0,3000091.0,3000092.0,3000093.0,3000094.0,3000095.0,3000096.0,3000097.0,3000098.0,3000099.0,3000100.0],fromList [4000001.0,4000002.0,4000003.0,4000004.0,4000005.0,4000006.0,4000007.0,4000008.0,4000009.0,4000010.0,4000011.0,4000012.0,4000013.0,4000014.0,4000015.0,4000016.0,4000017.0,4000018.0,4000019.0,4000020.0,4000021.0,4000022.0,4000023.0,4000024.0,4000025.0,4000026.0,4000027.0,4000028.0,4000029.0,4000030.0,4000031.0,4000032.0,4000033.0,4000034.0,4000035.0,4000036.0,4000037.0,4000038.0,4000039.0,4000040.0,4000041.0,4000042.0,4000043.0,4000044.0,4000045.0,4000046.0,4000047.0,4000048.0,4000049.0,4000050.0,4000051.0,4000052.0,4000053.0,4000054.0,4000055.0,4000056.0,4000057.0,4000058.0,4000059.0,4000060.0,4000061.0,4000062.0,4000063.0,4000064.0,4000065.0,4000066.0,4000067.0,4000068.0,4000069.0,4000070.0,4000071.0,4000072.0,4000073.0,4000074.0,4000075.0,4000076.0,4000077.0,4000078.0,4000079.0,4000080.0,4000081.0,4000082.0,4000083.0,4000084.0,4000085.0,4000086.0,4000087.0,4000088.0,4000089.0,4000090.0,4000091.0,4000092.0,4000093.0,4000094.0,4000095.0,4000096.0,4000097.0,4000098.0,4000099.0,4000100.0])
3,842,955,664 bytes allocated in the heap
16,390,368 bytes copied during GC
8,469,360 bytes maximum residency (6 sample(s))
2,122,880 bytes maximum slop
24 MB total memory in use (7 MB lost due to fragmentation)
Tot time (elapsed) Avg pause Max pause
Gen 0 7411 colls, 7411 par 0.20s 0.06s 0.0000s 0.0004s
Gen 1 6 colls, 5 par 0.00s 0.00s 0.0002s 0.0008s
Parallel GC work balance: 1.00% (serial 0%, perfect 100%)
TASKS: 10 (1 bound, 9 peak workers (9 total), using -N4)
SPARKS: 3 (0 converted, 0 overflowed, 0 dud, 3 GC'd, 0 fizzled)
INIT time 0.00s ( 0.00s elapsed)
MUT time 0.77s ( 0.69s elapsed)
GC time 0.20s ( 0.06s elapsed)
EXIT time 0.00s ( 0.00s elapsed)
Total time 0.97s ( 0.76s elapsed)
Alloc rate 5,018,806,918 bytes per MUT second
Productivity 78.9% of total user, 101.5% of total elapsed
gc_alloc_block_sync: 6988
whitehole_spin: 0
gen[0].sync: 0
gen[1].sync: 0
real 0m0.759s
user 0m0.972s
sys 0m0.158s
vh:haskell apple1$ time ./bench
(fromList [1000001.0,1000002.0,1000003.0,1000004.0,1000005.0,1000006.0,1000007.0,1000008.0,1000009.0,1000010.0,1000011.0,1000012.0,1000013.0,1000014.0,1000015.0,1000016.0,1000017.0,1000018.0,1000019.0,1000020.0,1000021.0,1000022.0,1000023.0,1000024.0,1000025.0,1000026.0,1000027.0,1000028.0,1000029.0,1000030.0,1000031.0,1000032.0,1000033.0,1000034.0,1000035.0,1000036.0,1000037.0,1000038.0,1000039.0,1000040.0,1000041.0,1000042.0,1000043.0,1000044.0,1000045.0,1000046.0,1000047.0,1000048.0,1000049.0,1000050.0,1000051.0,1000052.0,1000053.0,1000054.0,1000055.0,1000056.0,1000057.0,1000058.0,1000059.0,1000060.0,1000061.0,1000062.0,1000063.0,1000064.0,1000065.0,1000066.0,1000067.0,1000068.0,1000069.0,1000070.0,1000071.0,1000072.0,1000073.0,1000074.0,1000075.0,1000076.0,1000077.0,1000078.0,1000079.0,1000080.0,1000081.0,1000082.0,1000083.0,1000084.0,1000085.0,1000086.0,1000087.0,1000088.0,1000089.0,1000090.0,1000091.0,1000092.0,1000093.0,1000094.0,1000095.0,1000096.0,1000097.0,1000098.0,1000099.0,1000100.0],fromList [2000001.0,2000002.0,2000003.0,2000004.0,2000005.0,2000006.0,2000007.0,2000008.0,2000009.0,2000010.0,2000011.0,2000012.0,2000013.0,2000014.0,2000015.0,2000016.0,2000017.0,2000018.0,2000019.0,2000020.0,2000021.0,2000022.0,2000023.0,2000024.0,2000025.0,2000026.0,2000027.0,2000028.0,2000029.0,2000030.0,2000031.0,2000032.0,2000033.0,2000034.0,2000035.0,2000036.0,2000037.0,2000038.0,2000039.0,2000040.0,2000041.0,2000042.0,2000043.0,2000044.0,2000045.0,2000046.0,2000047.0,2000048.0,2000049.0,2000050.0,2000051.0,2000052.0,2000053.0,2000054.0,2000055.0,2000056.0,2000057.0,2000058.0,2000059.0,2000060.0,2000061.0,2000062.0,2000063.0,2000064.0,2000065.0,2000066.0,2000067.0,2000068.0,2000069.0,2000070.0,2000071.0,2000072.0,2000073.0,2000074.0,2000075.0,2000076.0,2000077.0,2000078.0,2000079.0,2000080.0,2000081.0,2000082.0,2000083.0,2000084.0,2000085.0,2000086.0,2000087.0,2000088.0,2000089.0,2000090.0,2000091.0,2000092.0,2000093.0,2000094.0,2000095.0,2000096.0,2000097.0,2000098.0,2000099.0,2000100.0],fromList [3000001.0,3000002.0,3000003.0,3000004.0,3000005.0,3000006.0,3000007.0,3000008.0,3000009.0,3000010.0,3000011.0,3000012.0,3000013.0,3000014.0,3000015.0,3000016.0,3000017.0,3000018.0,3000019.0,3000020.0,3000021.0,3000022.0,3000023.0,3000024.0,3000025.0,3000026.0,3000027.0,3000028.0,3000029.0,3000030.0,3000031.0,3000032.0,3000033.0,3000034.0,3000035.0,3000036.0,3000037.0,3000038.0,3000039.0,3000040.0,3000041.0,3000042.0,3000043.0,3000044.0,3000045.0,3000046.0,3000047.0,3000048.0,3000049.0,3000050.0,3000051.0,3000052.0,3000053.0,3000054.0,3000055.0,3000056.0,3000057.0,3000058.0,3000059.0,3000060.0,3000061.0,3000062.0,3000063.0,3000064.0,3000065.0,3000066.0,3000067.0,3000068.0,3000069.0,3000070.0,3000071.0,3000072.0,3000073.0,3000074.0,3000075.0,3000076.0,3000077.0,3000078.0,3000079.0,3000080.0,3000081.0,3000082.0,3000083.0,3000084.0,3000085.0,3000086.0,3000087.0,3000088.0,3000089.0,3000090.0,3000091.0,3000092.0,3000093.0,3000094.0,3000095.0,3000096.0,3000097.0,3000098.0,3000099.0,3000100.0],fromList [4000001.0,4000002.0,4000003.0,4000004.0,4000005.0,4000006.0,4000007.0,4000008.0,4000009.0,4000010.0,4000011.0,4000012.0,4000013.0,4000014.0,4000015.0,4000016.0,4000017.0,4000018.0,4000019.0,4000020.0,4000021.0,4000022.0,4000023.0,4000024.0,4000025.0,4000026.0,4000027.0,4000028.0,4000029.0,4000030.0,4000031.0,4000032.0,4000033.0,4000034.0,4000035.0,4000036.0,4000037.0,4000038.0,4000039.0,4000040.0,4000041.0,4000042.0,4000043.0,4000044.0,4000045.0,4000046.0,4000047.0,4000048.0,4000049.0,4000050.0,4000051.0,4000052.0,4000053.0,4000054.0,4000055.0,4000056.0,4000057.0,4000058.0,4000059.0,4000060.0,4000061.0,4000062.0,4000063.0,4000064.0,4000065.0,4000066.0,4000067.0,4000068.0,4000069.0,4000070.0,4000071.0,4000072.0,4000073.0,4000074.0,4000075.0,4000076.0,4000077.0,4000078.0,4000079.0,4000080.0,4000081.0,4000082.0,4000083.0,4000084.0,4000085.0,4000086.0,4000087.0,4000088.0,4000089.0,4000090.0,4000091.0,4000092.0,4000093.0,4000094.0,4000095.0,4000096.0,4000097.0,4000098.0,4000099.0,4000100.0])
real 0m0.717s
user 0m0.694s
sys 0m0.021s
为什么它不能并行运行?我该如何修复它?我认为火花产生后需要一段时间才能得到处理,因此如果你没有很多工作要做,它们很可能会被GC'ed或失效 考虑一下这个计划:
import Control.Parallel.Strategies
import System.Environment
fib :: Int -> Int
fib n
| n <= 2 = n
| otherwise = fib (n-2) + fib (n-1)
test4 n = runEval $ do
a <- rpar (fib n)
b <- rpar (fib (n+1))
c <- rpar (fib (n+2))
d <- rpar (fib (n+3))
return (a,b,c,d)
main = do
n <- fmap (read.head) getArgs
print $ test4 n
在每种情况下,都会创建4个火花,但是对于较小的
n
值,火花管理器没有时间对其中任何一个进行评估,它们都会由主线程进行评估。当然有一个技巧可以让火花运行。下面是使用parMap
的另一种方法:
import Control.Monad.Par
import qualified Data.Vector.Unboxed as UV
passes = UV.fromList [1..1000000] :: UV.Vector Int
vector = UV.fromList [1..100] :: UV.Vector Double
test = runPar $ parMap go [1..4]
where go k = UV.foldr' (const (UV.map (+k))) vector passes
main = print test
这不会产生任何火花,但代码并行运行。分析统计显示总时间为1.63秒(已用0.93秒)
Threadscope非常便于观察HEC活动。编译时使用:
ghc -O2 -threaded -eventlog -rtsopts ...
并与以下内容一起运行:
./prog +RTS -N... -l
生成与Threadscope一起使用的事件日志文件。好吧,报告的
SPARKS
部分明确指出,共有3个SPARKS被GC捕获。考虑到代码总共创建了3个sparks,这表明GHC出于某种原因决定不使用您的并行性。在这种情况下,由于print
中的访问模式,我怀疑main
在spark有机会转换之前就开始计算x
。不知道为什么y
和z
的火花没有转换,但是-我会看看threadscope说了些什么。对不起,我还不明白这个问题。那我该怎么办?我正在创作的作品很繁重,需要一些时间来处理。我不明白为什么GHC更喜欢按顺序进行每一项。你做得够多了吗?我相信spark管理器的运行方式与上下文切换到线程的方式相同,即通过分配器。只是一个想法。。。
./prog +RTS -N... -l