Re: [Caml-list] file descriptor leaks?

[Basile Starynkevitch local <basile.starynkevitch@inria.fr>]

On Mon, May 03, 2004 at 04:32:32PM -0700, Ker Lutyn wrote:
[...]

> Assuming f does not close the fd when it's done, [...] is this
> better?
> 
> while true do
>   let fd, _ = Unix.accept sock in
>   let g fd = try f fd; Unix.close fd with e -> Unix.close fd; raise e in
>   ignore (Thread.create g fd)
> done
> 

Yes. First, a file descriptor is mostly heavy in the OS kernel side;
inside a process, an fd is just an integer. To free the fd (kernel)
resource, you *have* to call Unix.close (i.e. to call the close(2)
system call).

Second, there are no implicit call to the close(2) system call inside
the Ocaml system (there used to be, long time ago, implicit close of
channels by the GC. This finalization is gone).

So yes, every file descriptor you got thru accept has to be explicitly
closed. Some higher level functions in the Unix library happen to do
so.

-- 
Basile STARYNKEVITCH -- basile dot starynkevitch at inria dot fr
Project cristal.inria.fr - phone +33 1 3963 5197 - mobile 6 8501 2359
http://cristal.inria.fr/~starynke --- all opinions are only mine 

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