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From Rodrigo Kumpera <kump...@gmail.com>
Subject Re: [jira] Commented: (HARMONY-40) FileChannel assotiated with FileOutputStream not closed after closing output stream
Date Wed, 25 Jan 2006 12:59:25 GMT
Aren't channels supposed to hold references to the original streams?

On 1/24/06, Paulex Yang <paulex.yang@gmail.com> wrote:
> The patch does work in some case, but it is not enough.
>
> First, when the channel is closed, the relevant stream(FileInputStream,
> FileOutputStream or RandomAccessFile) also needs to closed. So only add
> codes to the FileOutputStream is not enough.
>
> Second, the FileOutputStream/FileInputStream will close itself in the
> finalize() method(as Java spec says), and with your patch, current
> implementation in Harmony will close the channel at that time, too. This
> is very dangerous, because if someone writes code like below, the fos
> may be garbage collected and closed, and channel will also be closed, so
> that the following operation on channel will throw unexpected exception.
> <code>
> .....
> FileChannel channel = null;
> try{
>     FileOutputStream fos = new FileOutputStream("somefile.txt", false);
>     channel = fos.getChannel();
> }catch(Exception e){
> }
> /*continue operate on channel*/
> .....
> </code>
>
> Third, the native close operation should only be executed once, so that
> some synchronization mechanism on the channel and stream should be
> introduced, which should also avoid deadlock when one thread is calling
> fos.close() while the other is calling channel.close().
>
> As a conclusion, the close issue is yet another reason that the three
> classes IO package need to be refactored to based on same JNI interface
> with FileChannel. Pls. refer to my work on JIRA issue #42.
>
> Vladimir Strigun (JIRA)
> >     [ http://issues.apache.org/jira/browse/HARMONY-40?page=comments#action_12363705
]
> >
> > Vladimir Strigun commented on HARMONY-40:
> > -----------------------------------------
> >
> > Forced close of file current file channel in file output stream can be added (diff
for current FileOutputStream)
> > 173a174,177
> >
> >>               if (channel != null) {
> >>                       channel.close();
> >>                       channel = null;
> >>               }
> >>
> >
> >
> >> FileChannel assotiated with FileOutputStream not closed after closing output
stream
> >> -----------------------------------------------------------------------------------
> >>
> >>          Key: HARMONY-40
> >>          URL: http://issues.apache.org/jira/browse/HARMONY-40
> >>      Project: Harmony
> >>         Type: Bug
> >>   Components: Classlib
> >>     Reporter: Vladimir Strigun
> >>
> >
> >
> >> When I receive FileChannel from file output stream, write something to stream
and then close it, channel, assotiated with the stream is still open. I'll attach unit test
for the issue.
> >>
> >
> >
>
>
> --
> Paulex Yang
> China Software Development Lab
> IBM
>
>
>

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