This package provides a high-level Haskell interface to the WorkQueue library:
http://www.nd.edu/~ccl/software/workqueue/
Work Queue is a framework for building large
master-worker applications that span many
computers including clusters, clouds, and
grids. Work Queue applications are written in C,
Perl, or Python using a simple API that allows
users to define tasks, submit them to the queue,
and wait for completion. Tasks are executed by a
standard worker process that can run on any
available machine. Each worker calls home to the
master process, arranges for data transfer, and
executes the tasks. Together, the master and
worker handle a wide variety of failures,
allowing for dynamically scalable and robust
applications.
Example usage:
By default the master listens on 9123 on the localhost host.
Start a worker:
$ work_queue_worker -d all localhost 9123
Now we can execute the following master program:
module Main where
import Control.Distributed.CCTools.WorkQueue
import Control.Applicative ((<$>))
import qualified Data.ByteString.Char8 as BS (pack, putStrLn)
import Foreign.C.String (newCStringLen)
import Control.Monad (forM_)
mktask :: Show a => a -> IO Task
mktask v = do
let script = BS.pack . unlines $ [
"t=$(echo $RANDOM % 10 | bc)"
, "sleep $t"
, "echo " ++ show v
]
t <- task $ cmd "bash script.sh"
specifyBuffer t script (remote "script.sh") False
specifyTag t $ show v
return t
printStats :: WorkQueue -> IO ()
printStats q = do
s <- getStats q
print $ map ($ s) [tasksRunning, tasksWaiting, tasksComplete]
processResult :: WorkQueue -> Task -> IO ()
processResult q r = do
putStrLn $ "Got: " ++ show (tag r)
BS.putStrLn . output $ r
delete r
main = do
setDebugFlags [All]
q <- workqueue defaultQParams
ts <- mapM mktask [1..10]
forM_ ts (submit q)
eventLoop q (seconds 1) printStats processResult
putStrLn "Done!"