Question

我已经编写了下面的代码，并注意到killThread块并且线程仍在继续。只有当我在forkProcess中执行它时才会发生这种情况，如果我删除forkProcess，一切都按预期工作。

代码

{-# LANGUAGE TupleSections #-}
module Main where

import Control.Concurrent
import Control.Monad
import System.Posix.Process

{-# NOINLINE primes #-}
primes :: [Integer]
primes = 2:[x | x <- [3..], all (not . flip isDivisorOf x) (takeWhile (< truncate (sqrt $ fromInteger x :: Double)) primes)]
  where x `isDivisorOf` y = y `rem` x == 0

evaluator :: Show a => [a] -> IO ()
evaluator xs = do
  putStrLn "[Evaluator] Started evaluator."
  forM_ xs $ \x -> putStrLn $ "[Evaluator] Got result: " ++ show x
  putStrLn "[Evaluator] Evaluator exited."

test :: IO ThreadId
test = forkIO (evaluator $ filter ((== 13) . flip rem (79 * 5 * 7 * 3 * 3 * 2 * 3)) primes) -- Just some computation that doesn't finsish too fast

main :: IO ()
main = do
  pid <- forkProcess $ do
    a <- test
    threadDelay $ 4000 * 1000
    putStrLn "Canceling ..."
    killThread a
    putStrLn "Canceled"
  void $ getProcessStatus True False pid

输出

$ ghc test.hs -O -fforce-recomp -threaded -eventlog -rtsopts # I also tried with -threaded
$ ./test +RTS -N2  # I also tried without -N
[Evaluator] Started evaluator.
[Evaluator] Got result: 13
[Evaluator] Got result: 149323
[Evaluator] Got result: 447943
[Evaluator] Got result: 597253
[Evaluator] Got result: 746563
[Evaluator] Got result: 1045183
Canceling ...
[Evaluator] Got result: 1194493
[Evaluator] Got result: 1642423
[Evaluator] Got result: 1791733
[Evaluator] Got result: 2090353
[Evaluator] Got result: 2687593
[Evaluator] Got result: 3135523
[Evaluator] Got result: 3284833
[Evaluator] Got result: 4777933
[Evaluator] Got result: 5375173
^C[Evaluator] Got result: 5524483
^C

这不是通常的问题，没有内存分配，因此GHC的线程调度程序不运行。我通过使用+RTS -sstderr运行程序来验证，这表明垃圾收集器经常运行。我在linux 64bit上运行它。

Answer 1

此bug report注意到forkProcess屏蔽子进程中的异步异常，尽管文档中没有这样的说明。该行为应在7.8.1发布时修复。

当然，如果屏蔽了异步异常，throw内的killThread将无限期阻止。如果您只是删除包含main和forkProcess的{{1}}中的行，则该程序会按预期运行：

getProcessStatus

我使用module Main where import Control.Concurrent import Control.Monad import System.Posix.Process {-# NOINLINE primes #-} primes :: [Integer] primes = 2:[ x | x <- [3..], all (not . flip isDivisorOf x) (takeWhile (< truncate (sqrt $ fromInteger x :: Double)) primes)] where x `isDivisorOf` y = y `rem` x == 0 evaluator :: Show a => [a] -> IO () evaluator = mapM_ $ \x -> putStrLn $ "[Evaluator] Got result: " ++ show x test :: IO ThreadId test = forkIO (evaluator $ filter ((== 13) . flip rem (79 * 5 * 7 * 3 * 3 * 2 * 3)) primes) -- Just some computation that doesn't finsish too fast main :: IO () main = do a <- test threadDelay $ 4000 * 1000 putStrLn "Canceling ..." killThread a putStrLn "Canceled"构建它并使用ghc --make -threaded async.hs运行。

如果由于某种原因需要单独的进程，则必须在GHC 7.6.3中的子进程中手动取消屏蔽异步异常。

forkIO / killThread与forkProcess的交互

代码

输出

1 个答案: