From: Gennady Bystritsky <Gennady.Bystritsky@...>
Date: 2006-04-18T03:33:38+09:00
Subject: Re: IO not closed by GC

Even GC.start does not guarantee that the garbage collection will be
actually started, it is just a hint after all. And I am not sure that
even when an IO object is being garbage collected, there will be an
implicit call to close(). I personally would not expect it as no
finalizers are installed by default. 

So the programmer must take care to write the correct code, short or
long ;-).

Even if GC.start helped in your case, the overall code would be longer
(because of calls to GC.start) and work much worse (as GC does a lot
that you may not need for the moment) than what I have suggested. And
using blocks with popen is GUARANTEED to close descriptors properly. See
my point?

By the way, you are welcome.

Gennady.

> -----Original Message-----
> From: Stephan Maka [mailto:stephan@spaceboyz.net] 
> Sent: Monday, April 17, 2006 10:37
> To: ruby-talk ML
> Subject: Re: IO not closed by GC
> 
> Gennady Bystritsky wrote:
> > But you do not even know when GC will be run, so in your 
> case it might
> 
> Inserting 'GC.start; sleep 1' won't help...
> 
> > not even have kicked in. On the other hand, IO.popen has a 
> nice block 
> > form that gurantees that an underlying IO object will be closed 
> > properly. You can rewrite your code as:
> > 
> > os = IO.popen('uname -sr') { |io| io.readlines.to_s.strip }
> 
> That works, but is longer. Shorter code is more readable in general...
> 
> Anyway, I think an IO object should be closed when not being 
> needed anylonger.
> 
> 
> Stephan.
>