Small poll

[Chris Pressey]

On Wed, 17 Dec 2003 21:17:35 +0100
Pascal Brisset <pascal.brisset-ml@REDACTED> wrote:

> Chris Pressey writes:
>  >   foo(Bar) ->
>  >     ok = file:setcwd(moo(Bar)),
>  >     {ok, File} = file:open(zoo(Bar)),
>  >     {ok, Records} = read_records(File),
>  >     ok = file:close(File),
>  >     Records.
>  > 
>  > So, the intent of the function is clearly to fail outright with
>  > 'badmatch' if anything goes wrong.  foo/1's callers presumably wrap
>  > their calls to foo (or their calls to whatever eventually calls
>  > foo) in a catch. [...]
> 
> Note that if foo/1's caller catches failures from read_records/1,
> file descriptors will be leaked.  Days later, the beam process runs
> out of descriptors and strange things happen.  Been there.
> 
> What would seasoned Erlangers recommend to avoid this ?

Well, I am not a seasoned Erlanger[1], but I imagine most of them would
recommend spawning foo/1 into it's own process, then monitoring it or
linking to it.  Then, when the process running foo/1 dies, its
filehandles and other resources will be deallocated (IIRC.)

-Chris

[1] I just come with a little wasabi on the side.