Do I need to close a FileStream?

> On Mar 24, 2007, at 8:34 , Tim Johnson wrote:
>
> > Hi,
> >
> > Do I need to worry about closing a read-only FileStream when I am
> > done reading from it?
>
> Yes. Always. A common pattern is
>
>         f := ... open the file stream ....
>         [ ... do something with f ... ] ensure: [f close]
>
> This ensures f is closed even if there is an error in your processing
> code.
>
> > What happens if I don't?
>
> Bad Things ;) I'm not exactly sure.
>
> > How can I tell if I have lots of open files in my system?
> > "FileStream allInstances inspect"?
>
> You would need to use #allSubInstances and check if they're open.
>
> - Bert -
>
>
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> On Mar 24, 2007, at 8:34 , Tim Johnson wrote:
>
>> Hi,
>>
>> Do I need to worry about closing a read-only FileStream when I am  
>> done reading from it?
>
> Yes. Always. A common pattern is
>
> f := ... open the file stream ....
> [ ... do something with f ... ] ensure: [f close]
>
> This ensures f is closed even if there is an error in your  
> processing code.
>
>> What happens if I don't?
>
> Bad Things ;) I'm not exactly sure.
>
>> How can I tell if I have lots of open files in my system?  
>> "FileStream allInstances inspect"?
>
> You would need to use #allSubInstances and check if they're open.

>
> On Mar 24, 2007, at 3:45 AM, Kyle Hamilton wrote:
>
>> The underlying OS has only a certain number of file handles that it
>> can maintain open at a time.  On UNIX-like systems, there is also
>> possibly a maximum number of files per process.  If this limit is  
>> hit,
>> then no additional files can be opened, and on any attempt to do  
>> so an
>> error is returned.
>
> For some reason I was confused and thought that Squeak's garbage  
> collector would somehow make me immune from this.  Like when the  
> file was no longer being used, it would be closed and purged.

>
> On Mar 24, 2007, at 17:41 , Tim Johnson wrote:
>
> >
> > On Mar 24, 2007, at 3:45 AM, Kyle Hamilton wrote:
> >
> >> The underlying OS has only a certain number of file handles that it
> >> can maintain open at a time.  On UNIX-like systems, there is also
> >> possibly a maximum number of files per process.  If this limit is
> >> hit,
> >> then no additional files can be opened, and on any attempt to do
> >> so an
> >> error is returned.
> >
> > For some reason I was confused and thought that Squeak's garbage
> > collector would somehow make me immune from this.  Like when the
> > file was no longer being used, it would be closed and purged.
>
> Actually it is indeed. We use finalization for this [*]. However, you
> cannot know _when_ an object actually will be finalized, so you may
> be eating up handles nontheless.
>
> > Now I know otherwise :)
>
> It's good practice not to rely on finalization, but treat it as a
> safety net.
>
> - Bert -
>
> [*] See for example
> http://www.mail-archive.com/beginners@.../
> msg01719.html
> or
> http://www.google.com/search?q=squeak+finalization
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