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Groups > comp.lang.java.programmer > #10439

Re: java.io.File

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On 12/2/2011 11:31 AM, Mark wrote:
> On Fri, 2 Dec 2011 08:17:15 -0800 (PST), Lew<lewbloch@gmail.com>
> wrote:
>> Mark wrote:
>>> Lew wrote:
>>>> Mark wrote:
>>>>> Can a java.io.File object use a OS file descriptor?  I am trying to
>>>>> find the source of a fd leak in a[n] application.
>>>>
>>>> At some point, depending on the operations performed by the 'File' instance,
>>>> there may be a file descriptor involved, and then the 'File' instance certainly
>>>> does use it, at least indirectly via JVM system calls that proxy to OS system
>>>> calls.
>>>>
>>>>  From a Java perspective you should look for unclosed I/O streams/channels and
>>>> packratted 'File' instances rather than file descriptors.
>>>
>>> I've done a code inspection and the streams are all explicitly closed.
>>> There are a number of File objects used and I notice that File does
>>> not have a close() method so we have to rely on GC.
>>
>> If there were a 'close()' method, as there is with streams, it would have
>> nothing to do with GC.  'close()' is for resources (such as file handles).
>> GC is for heap memory.  I only suggested checking for packratted 'File'
>> instances as a foolish guess.  Now that I think about it, it is highly
>> unlikely that unclaimed instances would have anything to do with your issue.
>
> AFAIK many classes have a close() method to allow any underlying OS
> resources to be explicitly freed without needing to wait for the
> dispose() method to do this.  If the File method does uses file
> descriptors then we may assume that these could be left open until the
> object is destroyed during GC.

That will only happen during GC if there is a finalizer.

And the usage of finalizers to free resources usually
raises a lot of red flags!

Arne

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java.io.File Mark <i@dontgetlotsofspamanymore.net> - 2011-12-02 09:35 +0000
  Re: java.io.File Lew <lewbloch@gmail.com> - 2011-12-02 07:25 -0800
    Re: java.io.File Mark <i@dontgetlotsofspamanymore.net> - 2011-12-02 15:55 +0000
      Re: java.io.File Lew <lewbloch@gmail.com> - 2011-12-02 08:17 -0800
        Re: java.io.File Mark <i@dontgetlotsofspamanymore.net> - 2011-12-02 16:31 +0000
          Re: java.io.File markspace <-@.> - 2011-12-02 08:53 -0800
          Re: java.io.File Lew <lewbloch@gmail.com> - 2011-12-02 14:02 -0800
            Re: java.io.File Arne Vajhøj <arne@vajhoej.dk> - 2011-12-02 17:12 -0500
              Re: java.io.File Lew <lewbloch@gmail.com> - 2011-12-02 14:16 -0800
                Re: java.io.File Arne Vajhøj <arne@vajhoej.dk> - 2011-12-02 18:42 -0500
                Re: java.io.File Lars Enderin <lars.enderin@telia.com> - 2011-12-03 01:06 +0100
                Re: java.io.File Jukka Lahtinen <jtfjdehf@hotmail.com.invalid> - 2011-12-07 15:51 +0200
            Re: java.io.File Mark <i@dontgetlotsofspamanymore.net> - 2011-12-05 15:14 +0000
              Re: java.io.File markspace <-@.> - 2011-12-05 07:49 -0800
                Re: java.io.File Mark <i@dontgetlotsofspamanymore.net> - 2011-12-05 16:28 +0000
              Re: java.io.File Lew <lewbloch@gmail.com> - 2011-12-05 15:25 -0800
                Re: java.io.File Mark <i@dontgetlotsofspamanymore.net> - 2011-12-06 10:29 +0000
          Re: java.io.File Arne Vajhøj <arne@vajhoej.dk> - 2011-12-02 17:08 -0500
      Re: java.io.File Roedy Green <see_website@mindprod.com.invalid> - 2011-12-03 00:57 -0800
    Re: java.io.File Mayeul <mayeul.marguet@free.fr> - 2011-12-02 17:33 +0100
      Re: java.io.File Lew <lewbloch@gmail.com> - 2011-12-02 14:07 -0800
        Re: java.io.File Mayeul <mayeul.marguet@free.fr> - 2011-12-06 15:52 +0100
          Re: java.io.File Lew <lewbloch@gmail.com> - 2011-12-06 09:23 -0800

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