AW: [Caml-list] Channels not closed on gc?

[Gerd Stolpmann <info@gerd-stolpmann.de>]

Am 21.05.2012 13:23:36 schrieb(en) Lauri Alanko:
> I only recently noticed that ocaml does not close open channels when  
> they are garbage collected. This is evidently intentional behavior,  
> but it was quite unexpected.
> 
> To be clear, I do think it's bad style to rely on GC for releasing OS  
> resources, but that doesn't explain why GC shouldn't do this if the  
> programmer has failed to explicitly close the channel. And if the  
> intention were to _enforce_ good style, the channel finaliser would  
> spout out an error or warning upon detecting that the channel hasn't  
> yet been closed, instead of just silently leaking file handles like  
> it does currently.
> 
> It is of course trivial to "fix" this by attaching a simple  
> finaliser, but the fact that this is not done by default makes me  
> suspect that there would be something fishy with this approach. So,  
> what's the rationale for the current behavior?

It's predictable.

Closing a channel is not only about releasing OS resources. Imagine the  
channel is actually a pipe - closing it means to signal EOF, i.e. it's  
a way of notifying another program about an event. This should not  
happen behind one's back.

Closing a regular file would in deed be harmless, but there is no  
generic way to identify such channels (in the OS).

Gerd

> Thanks,
> 
> 
> Lauri
> 
> 
> 
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Gerd Stolpmann, Darmstadt, Germany    gerd@gerd-stolpmann.de
Creator of GODI and camlcity.org.
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