[Haskell-cafe] Re: sendfile leaking descriptors on Linux?
spam at scientician.net
Sat Feb 6 11:44:29 EST 2010
Bardur Arantsson wrote:
(sorry about replying-to-self)
> During yet another bout of debugging, I've added even more "I am here"
> instrumentation code to the SendFile code, and the culprit seems to be
I think I've pretty much confirmed this.
I've changed the code again. This time to:
> sendfile :: Fd -> Fd -> Ptr Int64 -> Int64 -> IO Int64
> sendfile out_fd in_fd poff bytes = do
> putStrLn "PRE-threadWaitWrite"
> -- threadWaitWrite out_fd
> -- putStrLn "AFTER threadWaitWrite"
> sbytes <- c_sendfile out_fd in_fd poff (fromIntegral bytes)
> putStrLn $ "AFTER c_sendfile; result was: " ++ (show sbytes)
> if sbytes <= -1
> then do errno <- getErrno
> if errno == eAGAIN
> then do
> threadDelay 100
> sendfile out_fd in_fd poff bytes
> else throwErrno "Network.Socket.SendFile.Linux"
> else return (fromIntegral sbytes)
That is, I removed the threadWaitWrite in favor of just adding a
"threadDelay 100" when eAGAIN is encountered.
With this code, I cannot provoke the leak.
Unfortunately this isn't really a solution -- the CPU is pegged at
~50% when I do this and it's not exactly elegant to have a hardcoded
100 ms delay in there. :)
I'm hoping that someone who understands the internals of GHC can chime
in here with some kind of explanation as to if/why/how threadWaitWrite can
fail in this way.
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