abstract-deque-0.2.2: Data/Concurrent/Deque/Tests.hs
{-# LANGUAGE BangPatterns, RankNTypes, CPP #-}
-- | This module contains a battery of simple tests for queues
-- implementing the interface defined in
-- ` Data.Concurrent.Deque.Class`.
{-# OPTIONS_GHC -fwarn-incomplete-patterns #-}
module Data.Concurrent.Deque.Tests
(
-- * Tests for simple FIFOs.
test_fifo_filldrain, test_fifo_OneBottleneck, tests_fifo,
-- * Tests for Work-stealing queues.
test_ws_triv1, test_ws_triv2, tests_wsqueue,
-- * All deque tests, aggregated.
tests_all,
-- * Testing parameters
numElems, getNumAgents, producerRatio,
-- * Utility for controlling the number of threads used by generated tests.
setTestThreads,
-- * Test initialization, reading common configs
stdTestHarness
)
where
import Data.Concurrent.Deque.Class as C
import qualified Data.Concurrent.Deque.Reference as R
import Control.Monad
import Data.Array as A
import Data.IORef
import Data.Int
import qualified Data.Set as S
-- import System.Mem.StableName
import Text.Printf
import GHC.Conc (throwTo, threadDelay, myThreadId)
import Control.Concurrent.MVar
import Control.Concurrent (yield, forkOS, forkIO, ThreadId)
import Control.Exception (catch, SomeException, fromException, bracket, AsyncException(ThreadKilled))
import System.Environment (withArgs, getArgs, getEnvironment)
import System.IO (hPutStrLn, stderr, hFlush, stdout)
import System.IO.Unsafe (unsafePerformIO)
import System.Random (randomIO, randomRIO)
import qualified Test.Framework as TF
import Test.Framework.Providers.HUnit (hUnitTestToTests)
import Test.HUnit as HU
import Debug.Trace (trace)
#if __GLASGOW_HASKELL__ >= 704
import GHC.Conc (getNumCapabilities, setNumCapabilities, getNumProcessors)
#else
import GHC.Conc (numCapabilities)
getNumCapabilities :: IO Int
getNumCapabilities = return numCapabilities
setNumCapabilities :: Int -> IO ()
setNumCapabilities = error "setNumCapabilities not supported in this older GHC! Set NUMTHREADS and +RTS -N to match."
getNumProcessors :: IO Int
getNumProcessors = return 1
#endif
theEnv :: [(String, String)]
theEnv = unsafePerformIO getEnvironment
----------------------------------------------------------------------------------------------------
-- TODO: In addition to setting these parameters from environment
-- variables, it would be nice to route all of this through a
-- configuration record, so that it can be changed programmatically.
-- How many elements should each of the tests pump through the queue(s)?
numElems :: Int
numElems = case lookup "NUMELEMS" theEnv of
Nothing -> 100 * 1000 -- 500000
Just str -> warnUsing ("NUMELEMS = "++str) $
read str
forkThread :: IO () -> IO ThreadId
forkThread = case lookup "OSTHREADS" theEnv of
Nothing -> forkIO
Just x -> warnUsing ("OSTHREADS = "++x) $
case x of
"0" -> forkIO
"False" -> forkIO
"1" -> forkOS
"True" -> forkOS
oth -> error$"OSTHREAD environment variable set to unrecognized option: "++oth
-- | How many communicating agents are there? By default one per
-- thread used by the RTS.
getNumAgents :: IO Int
getNumAgents = case lookup "NUMAGENTS" theEnv of
Nothing -> getNumCapabilities
Just str -> warnUsing ("NUMAGENTS = "++str) $
return (read str)
-- | It is possible to have imbalanced concurrency where there is more
-- contention on the producing or consuming side (which corresponds to
-- settings of this parameter less than or greater than 1).
producerRatio :: Double
producerRatio = case lookup "PRODUCERRATIO" theEnv of
Nothing -> 1.0
Just str -> warnUsing ("PRODUCERRATIO = "++str) $
read str
warnUsing :: String -> a -> a
warnUsing str a = trace (" [Warning]: Using environment variable "++str) a
-- | Dig through the test constructors to find the leaf IO actions and bracket them
-- with a thread-setting action.
setTestThreads :: Int -> HU.Test -> HU.Test
setTestThreads nm tst = loop False tst
where
loop flg x =
case x of
TestLabel lb t2 -> TestLabel (decor flg lb) (loop True t2)
TestList ls -> TestList (map (loop flg) ls)
TestCase io -> TestCase (bracketThreads nm io)
-- We only need to insert the numcapabilities in the description string ONCE:
decor False lb = "N"++show nm++"_"++ lb
decor True lb = lb
bracketThreads :: Int -> IO a -> IO a
bracketThreads n act =
bracket (getNumCapabilities)
setNumCapabilities
(\_ -> do dbgPrint 1 ("\n [Setting # capabilities to "++show n++" before test] \n")
setNumCapabilities n
act)
stdTestHarness :: (IO Test) -> IO ()
stdTestHarness genTests = do
numAgents <- getNumAgents
putStrLn$ "Running with numElems "++show numElems++" and numAgents "++ show numAgents
putStrLn "Use NUMELEMS, NUMAGENTS, NUMTHREADS to control the size of this benchmark."
args <- getArgs
np <- getNumProcessors
putStrLn $"Running on a machine with "++show np++" hardware threads."
-- We allow the user to set this directly, because the "-t" based regexp selection
-- of benchmarks is quite limited.
let all_threads = case lookup "NUMTHREADS" theEnv of
Just str -> [read str]
Nothing -> S.toList$ S.fromList$
[1, 2, np `quot` 2, np, 2*np ]
putStrLn $"Running tests for these thread settings: " ++show all_threads
all_tests <- genTests
-- Don't allow concurent tests (the tests are concurrent!):
withArgs (args ++ ["-j1","--jxml=test-results.xml"]) $ do
-- Hack, this shouldn't be necessary, but I'm having problems with -t:
tests <- case all_threads of
[one] -> do cap <- getNumCapabilities
unless (cap == one) $ setNumCapabilities one
return all_tests
_ -> return$ TestList [ setTestThreads n all_tests | n <- all_threads ]
TF.defaultMain$ hUnitTestToTests tests
----------------------------------------------------------------------------------------------------
-- Test a plain FIFO queue:
----------------------------------------------------------------------------------------------------
-- The type of data that we push over the queues.
type Elt = Int64
-- | This test serially fills up a queue and then drains it.
test_fifo_filldrain :: DequeClass d => d Elt -> IO ()
test_fifo_filldrain q =
do
dbgPrintLn 1 "\nTest FIFO queue: sequential fill and then drain"
dbgPrintLn 1 "==============================================="
-- let n = 1000
let n = fromIntegral numElems
dbgPrintLn 1$ "Done creating queue. Pushing "++show n++" elements:"
forM_ [1..n] $ \i -> do
pushL q i
when (i < 200) $ dbgPrint 1 $ printf " %d" i
dbgPrintLn 1 "\nDone filling queue with elements. Now popping..."
let loop 0 !sumR = return sumR
loop i !sumR = do
(x,_) <- spinPopBkoff q
when (i < 200) $ dbgPrint 1 $ printf " %d" x
loop (i-1) (sumR + x)
s <- loop n 0
let expected = sum [1..n] :: Elt
dbgPrint 1 $ printf "\nSum of popped vals: %d should be %d\n" s expected
when (s /= expected) (assertFailure "Incorrect sum!")
return ()
{-# INLINABLE test_fifo_OneBottleneck #-}
-- | This test splits the 'numAgents' threads into producers and
-- consumers which all communicate through a SINGLE queue. Each
-- thread performs its designated operation as fast as possible. The
-- 'Int' argument 'total' designates how many total items should be
-- communicated (irrespective of 'numAgents').
test_fifo_OneBottleneck :: DequeClass d => Bool -> Int -> d Elt -> IO ()
test_fifo_OneBottleneck doBackoff total q =
do
assertBool "test_fifo_OneBottleneck requires thread safe left end" (leftThreadSafe q)
assertBool "test_fifo_OneBottleneck requires thread safe right end" (rightThreadSafe q)
dbgPrintLn 1$ "\nTest FIFO queue: producers & consumers thru 1 queue"
++(if doBackoff then " (with backoff)" else "(hard busy wait)")
dbgPrintLn 1 "======================================================"
bl <- nullQ q
dbgPrintLn 1$ "Check that queue is initially null: "++show bl
numAgents <- getNumAgents
let producers = max 1 (round$ producerRatio * (fromIntegral numAgents) / (producerRatio + 1))
consumers = max 1 (numAgents - producers)
perthread = total `quot` producers
(perthread2,remain) = total `quotRem` consumers
numCap <- getNumCapabilities
when (not doBackoff && (numCap == 1 || numCap < producers + consumers)) $
error$ "The aggressively busy-waiting version of the test can only run with the right thread settings."
dbgPrint 1 $ printf "Forking %d producer threads, each producing %d elements.\n" producers perthread
dbgPrint 1 $ printf "Forking %d consumer threads, each consuming ~%d elements.\n" consumers perthread2
forM_ [0..producers-1] $ \ ind ->
myfork "producer thread" $ do
let start = ind * perthread
dbgPrint 1 $ printf " * Producer thread %d pushing ints from %d to %d \n" ind start (start+perthread - 1)
forI_ start (start+perthread) $ \ i -> do
pushL q i
-- when (i < start + 10) $ dbgPrint 1 $ printf " [p%d] pushed %d \n" ind i
ls <- forkJoin consumers $ \ ind ->
let mymax = if ind==0 then perthread2 + remain else perthread2
consume_loop summ maxiters i | i == mymax = return (summ, maxiters)
consume_loop !summ !maxiters i = do
(x,iters) <- if doBackoff then spinPopBkoff q
else spinPopHard q
when (i >= mymax - 10) $ dbgPrint 1 $ printf " [c%d] popped #%d = %d \n" ind i x
consume_loop (summ+x) (max maxiters iters) (i+1)
in consume_loop 0 0 0
let finalSum = Prelude.sum (map fst ls)
dbgPrintLn 1$ "Consumers DONE. Maximum retries for each consumer thread: "++ show (map snd ls)
dbgPrintLn 1$ "Final sum: "++ show finalSum
assertEqual "Correct final sum" (expectedSum (fromIntegral$ producers * perthread)) finalSum
dbgPrintLn 1$ "Checking that queue is finally null..."
b <- nullQ q
if b then dbgPrintLn 1$ "Sum matched expected, test passed."
else assertFailure "Queue was not empty!!"
-- | This test uses a separate queue per producer/consumer pair. The queues
-- are used in a single-writer single-reader.
test_contention_free_parallel :: DequeClass d => Bool -> Int -> IO (d Elt) -> IO ()
test_contention_free_parallel doBackoff total newqueue =
do
dbgPrintLn 1$ "\nTest FIFO queue: producers & consumers thru N queues"
++(if doBackoff then " (with backoff)" else "(hard busy wait)")
dbgPrintLn 1 "======================================================"
mv <- newEmptyMVar
numAgents <- getNumAgents
let producers = max 1 (round$ producerRatio * (fromIntegral numAgents) / (producerRatio + 1))
consumers = producers -- Must be matched
perthread = total `quot` producers
qs <- sequence (replicate consumers newqueue)
numCap <- getNumCapabilities
when (not doBackoff && (numCap == 1 || numCap < producers + consumers)) $
error$ "The aggressively busy-waiting version of the test can only run with the right thread settings."
dbgPrint 1 $ printf "Forking %d producer threads, each producing %d elements.\n" producers perthread
dbgPrint 1 $ printf "Forking %d consumer threads, each consuming %d elements.\n" consumers perthread
forM_ (zip [0..producers-1] qs) $ \ (id, q) ->
myfork "producer thread" $
let start = id*perthread in
forI_ 0 perthread $ \ i -> do
pushL q i
-- when (i - id*producers < 10) $ dbgPrint 1 $ printf " [%d] pushed %d \n" id i
forM_ (zip [0..consumers-1] qs) $ \ (id, q) ->
myfork "consumer thread" $ do
let consume_loop sum maxiters i | i == perthread = return (sum, maxiters)
consume_loop !sum !maxiters i = do
(x,iters) <- if doBackoff then spinPopBkoff q
else spinPopHard q
when (i < 10) $ dbgPrint 1 $ printf " [%d] popped #%d = %d \n" id i x
unless (x == fromIntegral i) $
error $ "Message out of order! Expected "++show i++" recevied "++show x
consume_loop (sum+x) (max maxiters iters) (i+1)
pr <- consume_loop 0 0 0
putMVar mv pr
dbgPrint 1 $ printf "Reading sums from MVar...\n"
ls <- mapM (\_ -> takeMVar mv) [1..consumers]
let finalSum = Prelude.sum (map fst ls)
dbgPrintLn 1$ "Consumers DONE. Maximum retries for each consumer thread: "++ show (map snd ls)
dbgPrintLn 1$ "All messages received in order. Final sum: "++ show finalSum
assertEqual "Correct final sum" (fromIntegral producers * expectedSum (fromIntegral perthread)) finalSum
dbgPrintLn 1$ "Checking that queue is finally null..."
bs <- mapM nullQ qs
if all id bs
then dbgPrintLn 1$ "Sum matched expected, test passed."
else assertFailure "Queue was not empty!!"
-- | This test uses a number of producer and consumer threads which push and pop
-- elements from random positions in an array of FIFOs.
test_random_array_comm :: DequeClass d => Int -> Int -> IO (d Elt) -> IO ()
test_random_array_comm size total newqueue = do
assertBool "positive size" (size > 0)
qs <- sequence (replicate size newqueue)
-- arr <- V.thaw $ V.fromlist qs
let arr = A.listArray (0,size-1) qs
assertBool "test_random_array_comm requires thread safe left end" (leftThreadSafe (head qs))
assertBool "test_random_array_comm requires thread safe right end" (rightThreadSafe (head qs))
dbgPrintLn 1$ "\nTest FIFO queue: producers & consumers select random queues"
dbgPrintLn 1 "======================================================"
numAgents <- getNumAgents
let producers = max 1 (round$ producerRatio * (fromIntegral numAgents) / (producerRatio + 1))
consumers = max 1 (numAgents - producers)
perthread = fromIntegral (total `quot` producers)
(perthread2,remain) = total `quotRem` consumers
dbgPrintLn 1 $ printf "Forking %d producer threads, each producing %d elements.\n" producers perthread
dbgPrintLn 1 $ printf "Forking %d consumer threads, each consuming ~%d elements.\n" consumers perthread2
forM_ [0..producers-1] $ \ ind ->
myfork "producer thread" $
for_ 0 perthread $ \ i -> do
-- Randomly pick a position:
ix <- randomRIO (0,size - 1) :: IO Int
pushL (arr ! ix) i
-- when (i - ind*producers < 10) $ dbgPrint 1 $ printf " [%d] pushed %d \n" ind i
-- Each consumer doesn't quit until it has popped "perthread":
sums <- forkJoin consumers $ \ ind ->
let mymax = if ind==0 then perthread2 + remain else perthread2
consume_loop summ i | i == mymax = return summ
consume_loop !summ i = do
-- Randomly pick a position:
ix <- randomRIO (0,size-1) :: IO Int
-- Try to pop something, but not too hard:
m <- spinPopN 100 (tryPopR (arr ! ix))
case m of
Just x -> do
when (i < 10) $ dbgPrint 1 $ printf " [%d] popped #%d = %d\n" ind i x
consume_loop (summ+x) (i+1)
Nothing ->
consume_loop summ i
in consume_loop 0 0
dbgPrintLn 1 "Reading sums from MVar..."
let finalSum = Prelude.sum sums
dbgPrintLn 1$ "Final sum: "++ show finalSum ++ ", per-consumer sums: "++show sums
dbgPrintLn 1$ "Checking that queue is finally null..."
assertEqual "Correct final sum" (fromIntegral producers * expectedSum perthread) finalSum
bs <- mapM nullQ qs
if all id bs
then dbgPrintLn 1$ "Sum matched expected, test passed."
else assertFailure "Queue was not empty!!"
-- Sum of first N numbers, starting with ZERO
expectedSum :: Integral a => a -> a
expectedSum n = (n * (n - 1)) `quot` 2
------------------------------------------------------------
-- | This creates an HUnit test list to perform all the tests that apply to a
-- single-ended (threadsafe) queue. It requires thread safety at /both/ ends.
tests_fifo :: DequeClass d => (forall elt. IO (d elt)) -> Test
tests_fifo newq = TestLabel "single-ended-queue-tests"$ TestList $
tests_basic newq ++
tests_fifo_exclusive newq
-- | Tests exclusive to single-ended (threadsafe) queues:
tests_fifo_exclusive :: DequeClass d => (forall elt. IO (d elt)) -> [Test]
tests_fifo_exclusive newq =
[ TestLabel "test_fifo_OneBottleneck_backoff" (TestCase$ assert $ newq >>= test_fifo_OneBottleneck True numElems)
-- , TestLabel "test_fifo_OneBottleneck_aggressive" (TestCase$ assert $ newq >>= test_fifo_OneBottleneck False numElems)
-- , TestLabel "test the tests" (TestCase$ assert $ assertFailure "This SHOULD fail.")
] ++
[ TestLabel ("test_random_array_comm_"++show size)
(TestCase$ assert $ test_random_array_comm size numElems newq)
| size <- [10,100]
]
-- | Tests that don't require thread safety at either end.
tests_basic :: DequeClass d => (forall elt. IO (d elt)) -> [Test]
tests_basic newq =
[ TestLabel "test_fifo_filldrain" (TestCase$ assert $ newq >>= test_fifo_filldrain)
, TestLabel "test_contention_free_parallel" (TestCase$ assert $ test_contention_free_parallel True numElems newq)
]
----------------------------------------------------------------------------------------------------
-- Test a Work-stealing queue:
----------------------------------------------------------------------------------------------------
-- | Trivial test: push then pop.
test_ws_triv1 :: PopL d => d [Char] -> IO ()
test_ws_triv1 q = do
pushL q "hi"
Just x <- tryPopL q
assertEqual "test_ws_triv1" x "hi"
-- | Trivial test: push left, pop left and right.
test_ws_triv2 :: PopL d => d [Char] -> IO ()
test_ws_triv2 q = do
pushL q "one"
pushL q "two"
pushL q "three"
pushL q "four"
ls <- sequence [tryPopR q, tryPopR q,
tryPopL q, tryPopL q,
tryPopL q, tryPopR q ]
assertEqual "test_ws_triv2" ls
[Just "one",Just "two",Just "four",Just "three",Nothing,Nothing]
-- | This test uses a number of worker threads which randomly either push or pop work
-- to their local work stealing deque. Also, there are consumer (always thief)
-- threads which never produce and only consume.
test_random_work_stealing :: (DequeClass d, PopL d) => Int -> IO (d Elt) -> IO ()
test_random_work_stealing total newqueue = do
dbgPrintLn 1$ "\nTest FIFO queue: producers & consumers select random queues"
dbgPrintLn 1 "======================================================"
numAgents <- getNumAgents
let producers, consumers :: Int
perthread, realtotal, perthread2 :: Elt
producers = max 1 (round$ producerRatio * (fromIntegral numAgents) / (producerRatio + 1))
consumers = max 1 (fromIntegral numAgents - producers)
perthread = fromIntegral total `quot` fromIntegral producers
realtotal = perthread * fromIntegral producers
(perthread2,remain) = realtotal `quotRem` fromIntegral consumers
qs <- sequence (replicate producers newqueue)
-- A work-stealing deque only has ONE threadsafe end:
assertBool "test_random_array_comm requires thread safe right end" (rightThreadSafe (head qs))
let arr = A.listArray (0,producers - 1) qs
dbgPrint 1 $ printf "Forking %d producer threads, each producing %d elements.\n" producers perthread
dbgPrint 1 $ printf "Forking %d consumer threads, each consuming ~%d elements.\n" consumers perthread2
prod_results <- newEmptyMVar
forM_ (zip [0..producers-1] qs) $ \ (ind,myQ) -> do
myfork "producer thread" $
let loop :: Elt -> Elt -> Elt -> IO ()
loop i !pops !acc
| i == perthread = putMVar prod_results (pops,acc)
| otherwise = do
-- Randomly push or pop:
b <- randomIO :: IO Bool
if b then do
x <- spinPopN 100 (tryPopL myQ)
-- In the case where we pop, we do NOT advance 'i', saving that
-- for the next iteration that acutally does a push.
case x of
Nothing -> loop i pops acc
Just n -> loop i (pops+1) (n+acc)
else do
pushL myQ i
-- when (i - ind*producers < 10) $ dbgPrint 1 $ printf " [%d] pushed %d \n" ind i
loop (i+1) pops acc
in loop 0 0 0
-- In this version
consumer_sums <- forkJoin consumers $ \ ind ->
let mymax = if ind==0 then perthread2 + remain else perthread2
consume_loop !summ !successes i
| i == mymax = return (successes, summ)
| otherwise = do
-- Randomly pick a position:
ix <- randomRIO (0,producers - 1) :: IO Int
-- Try to pop something, but not too hard:
m <- spinPopN 100 (tryPopR (arr ! ix))
case m of
Just x -> do
when (i < 10) $ dbgPrint 1 $ printf " [%d] popped try#%d = %d\n" ind i x
consume_loop (summ+x) (successes+1) (i+1)
Nothing ->
consume_loop summ successes (i+1) -- Increment even if we don't get a result.
in do dbgPrintLn 1 (" Beginning consumer thread loop for "++show mymax ++" attempts.")
consume_loop 0 0 0
-- <-- Consumers are finished as of here.
dbgPrintLn 1 "Reading sums from MVar..."
prod_ls <- mapM (\_ -> takeMVar prod_results) [1..producers]
-- We sequentially read out the leftovers after all the parallel tasks are done:
leftovers <- forM qs $ \ q ->
let loop !cnt !acc = do
x <- tryPopR q -- This should work as a popR OR a popL.
case x of
Nothing -> return (cnt,acc)
Just n -> loop (cnt+1) (acc+n)
in loop 0 0
let finalSum = Prelude.sum (map snd consumer_sums ++
map snd prod_ls ++
map snd leftovers)
dbgPrintLn 0$ "Final sum: "++ show finalSum ++ ", producer/consumer/leftover sums: "++show (prod_ls, consumer_sums, leftovers)
dbgPrintLn 1$ "Total pop events: "++ show (Prelude.sum (map fst consumer_sums ++
map fst prod_ls ++
map fst leftovers))
++" should be "++ (show$ realtotal)
dbgPrintLn 1$ "Checking that queue is finally null..."
assertEqual "Correct final sum" (fromIntegral producers * expectedSum perthread) finalSum
bs <- mapM nullQ qs
if all id bs
then dbgPrintLn 1$ "Sum matched expected, test passed."
else assertFailure "Queue was not empty!!"
-- | Aggregate tests for work stealing queues. None of these require thread-safety
-- on the left end. There is some duplication with tests_fifo.
tests_wsqueue :: (PopL d) => (forall elt. IO (d elt)) -> Test
tests_wsqueue newq = TestLabel "work-stealing-deque-tests"$ TestList $
tests_wsqueue_exclusive newq ++
tests_basic newq
-- Internal: factoring this out.
tests_wsqueue_exclusive :: (PopL d) => (forall elt. IO (d elt)) -> [Test]
tests_wsqueue_exclusive newq =
[ TestLabel "test_ws_triv1" (TestCase$ assert $ newq >>= test_ws_triv1)
, TestLabel "test_ws_triv2" (TestCase$ assert $ newq >>= test_ws_triv2)
, TestLabel "test_random_work_stealing" (TestCase$ assert $ test_random_work_stealing numElems newq)
]
----------------------------------------------------------------------------------------------------
-- Combine all tests -- for a deques supporting all capabilities.
----------------------------------------------------------------------------------------------------
-- | This requires double ended queues that are threadsafe on BOTH ends.
tests_all :: (PopL d) => (forall elt. IO (d elt)) -> Test
tests_all newq = TestLabel "full-deque-tests"$ TestList $
tests_basic newq ++
tests_fifo_exclusive newq ++
tests_wsqueue_exclusive newq
----------------------------------------------------------------------------------------------------
-- Misc Helpers
----------------------------------------------------------------------------------------------------
----------------------------------------------------------------------------------------------------
-- Misc Helpers
----------------------------------------------------------------------------------------------------
myfork :: String -> IO () -> IO ThreadId
myfork msg = forkWithExceptions forkThread msg
-- Exceptions that walk up the fork tree of threads:
forkWithExceptions :: (IO () -> IO ThreadId) -> String -> IO () -> IO ThreadId
forkWithExceptions forkit descr action = do
parent <- myThreadId
forkit $
Control.Exception.catch action
(\ e ->
case fromException e of
-- Let threadKilled exceptions through.
Just ThreadKilled -> return ()
_ -> do
hPutStrLn stderr $ "Exception inside child thread "++show descr++": "++show e
throwTo parent (e::SomeException)
)
forkJoin :: Int -> (Int -> IO b) -> IO [b]
forkJoin numthreads action =
do
answers <- sequence (replicate numthreads newEmptyMVar) -- padding?
forM_ (zip [0..] answers) $ \ (ix,mv) ->
myfork "forkJoin worker" (action ix >>= putMVar mv)
-- Reading answers:
ls <- mapM readMVar answers
return ls
-- | Pop from the right end more gently.
spinPopBkoff :: DequeClass d => d t -> IO (t, Int)
spinPopBkoff q = loop 1
where
hardspinfor = 10
sleepevery = 1000
warnafter = 5000
errorafter = 1 * 1000 * 1000
loop n = do
when (n == warnafter)
(dbgPrintLn 0$ "Warning: Failed to pop "++ show warnafter ++
" times consecutively. That shouldn't happen in this benchmark.")
-- when (n == errorafter) (error "This can't be right. A queue consumer spun 1M times.")
x <- tryPopR q
case x of
-- This yields EVERY time. And yet we get these real bursts / runs of failure.
Nothing -> do
-- Every `sleepevery` times do a significant delay:
if n `mod` sleepevery == 0
then do dbgPrint 1 "!"
threadDelay n -- 1ms after 1K fails, 2 after 2K...
else when (n > hardspinfor) $ do
dbgPrint 1 "."
hFlush stdout
yield -- At LEAST yield... you'd think this is pretty strong backoff.
loop (n+1)
Just x -> return (x, n)
-- | This is always a crazy and dangerous thing to do -- GHC cannot deschedule this
-- spinning thread because it does not allocate. Thus one can run into a deadlock
-- situation where the consumer holds the capabilitity hostage, not letting the
-- producer run (and therefore unblock it).
spinPopHard :: (DequeClass d) => d t -> IO (t, Int)
spinPopHard q = loop 1
where
loop n = do
x <- tryPopR q
case x of
Nothing -> do loop (n+1)
Just x -> return (x, n)
spinPopN :: Int -> IO (Maybe t) -> IO (Maybe t)
spinPopN 0 _ = return Nothing
spinPopN tries act = do
x <- act
case x of
Nothing -> spinPopN (tries-1) act
res@(Just _) -> return res
-- My own forM for numeric ranges (not requiring deforestation optimizations).
-- Inclusive start, exclusive end.
{-# INLINE for_ #-}
for_ :: Monad m => Elt -> Elt -> (Elt -> m ()) -> m ()
for_ start end _fn | start > end = error "for_: start is greater than end"
for_ start end fn = loop start
where
loop !i | i == end = return ()
| otherwise = do fn i; loop (i+1)
forI_ :: Monad m => Int -> Int -> (Elt -> m ()) -> m ()
forI_ st en = for_ (fromIntegral st) (fromIntegral en)
----------------------------------------------------------------------------------------------------
-- DEBUGGING
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-- | Debugging flag shared by several modules.
-- This is activated by setting the environment variable DEBUG=1..5
dbg :: Int
dbg = case lookup "DEBUG" theEnv of
Nothing -> defaultDbg
Just "" -> defaultDbg
Just "0" -> defaultDbg
Just s ->
trace (" ! Responding to env Var: DEBUG="++s)$
case reads s of
((n,_):_) -> n
[] -> error$"Attempt to parse DEBUG env var as Int failed: "++show s
defaultDbg :: Int
defaultDbg = 0
-- | Print if the debug level is at or above a threshold.
dbgPrint :: Int -> String -> IO ()
dbgPrint lvl str = if dbg < lvl then return () else do
-- hPutStrLn stderr str
-- hPrintf stderr str
-- hFlush stderr
printf str
hFlush stdout
dbgPrintLn :: Int -> String -> IO ()
dbgPrintLn lvl str = dbgPrint lvl (str++"\n")