[Haskell-cafe] Re: sendfile leaking descriptors on Linux?

Bardur Arantsson spam at scientician.net
Fri Feb 5 02:56:12 EST 2010

Jeremy Shaw wrote:
> Actually,
> We should start by testing if native sendfile leaks file descriptors even
> when the whole file is sent. We have a test suite, but I am not sure if it
> tests for file handle leaking...

I should have posted this earlier, but the exact message I'm seeing in 
the case where the Bad Client disconnects is this:

    hums: Network.Socket.SendFile.Linux: resource vanished (Broken pipe)

Oddly, I haven't been able to reproduce this using a wget client with a 
^C during transfer. When I "disconnect" wget with ^C or "pkill wget" or 
even "pkill -9 wget", I get this message:

   hums: Network.Socket.SendFile.Linux: resource vanished (Connection 
reset by peer)

(and no leak, as observed by "lsof | grep hums").

So there appears to be some vital difference between the handling of the 
two cases.

Another observation which may be useful:

Before the sendfile' API change (Handle -> FilePath) in sendfile-0.6.x, 
my code used "withFile" to open the file and to ensure that it was 
closed. So it seems that withBinaryFile *should* also be fine. Unless 
the "Broken pipe" error somehow escapes the scope without causing a "close".

I don't have time to dig more right now, but I'll try to see if I can 
find out more later.


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