Thanks everyone, Dan, MapMI worked for me ...
Regards, Kashyap On Mon, Mar 18, 2013 at 12:42 AM, Petr Pudlák <petr....@gmail.com> wrote: > Hi Kashyap, > > you could also use iteratees or conduits for a task like that. The beauty > of such libraries is that they can ensure that a resource is always > properly disposed of. See this simple example: > https://gist.github.com/anonymous/5183107 > It prints the first line of each file given as an argument. After each > line is printed, the `fileConduit` pipe ensures that the handle is closed. > It also makes the program nicely composable. > > Best regards, > Petr > > > import Control.Monad > import Control.Monad.Trans.Class > > import Control.Monad.IO.Class > import Data.Conduit > > import Data.Conduit.List > import System.Environment > > import System.IO > > > {- | Accept file paths on input, output opened file handle, and ensure that > the > - handle is always closed after its downstream pipe finishes whatever work > on it. -} > > fileConduit :: MonadResource m => IOMode -> Conduit FilePath m Handle > > fileConduit mode = awaitForever process > > where > process file = bracketP (openFile file mode) closeWithMsg yield > > closeWithMsg h = do > > putStrLn "Closing file" > > > hClose h > > {- | Print the first line from each handle on input. Don't care about the > handle. -} > > firstLine :: MonadIO m => Sink Handle m () > > firstLine = awaitForever (liftIO . (hGetLine >=> putStrLn)) > > > main = do > > args <- getArgs > > > runResourceT $ sourceList args =$= fileConduit ReadMode $$ firstLine > > > > > 2013/3/17 C K Kashyap <ckkash...@gmail.com> > >> Hi, >> >> I am working on an automation that periodically fetches bug data from our >> bug tracking system and creates static HTML reports. Things worked fine >> when the bugs were in the order of 200 or so. Now I am trying to run it >> against 3000 bugs and suddenly I see things like - too many open handles, >> out of memory etc ... >> >> Here's the code snippet - http://hpaste.org/84197 >> >> It's a small snippet and I've put in the comments stating how I run into >> "out of file handles" or simply file not getting read due to lazy IO. >> >> I realize that putting ($!) using a trial/error approach is going to be >> futile. I'd appreciate some pointers into the tools I could use to get some >> idea of which expressions are building up huge thunks. >> >> >> Regards, >> Kashyap >> >> _______________________________________________ >> Haskell-Cafe mailing list >> Haskell-Cafe@haskell.org >> http://www.haskell.org/mailman/listinfo/haskell-cafe >> >> >
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