FilterOutputStream.close() throws exception from flush()

[Alan Bateman]

On 03/05/2014 01:04, Bernd Eckenfels wrote:
> Hello,
>
> back in 2011 there was a discussion about the new changed behavior of
> FilterOutputStream (and BufferedOutputStream) in regards to not anymore
> swalloging IOExceptions from flush() on this list (thats where I got
> the subject from).
>
> This was generally a very good improvement (and I am glad that
> https://bugs.openjdk.java.net/browse/JDK-6335274 thereby got fixed).
> However the implementation with the try-with-resource has a problem:
> when flush() and close() report the same exception instance the
> construction of the suppressed exception will actually fail with an
> IllegalArgumentException.
>
> This IllegalArgumentException of Throwable.addSuppressed is very
> unfortunate (it would be better simply ignore it).
>
> Anyway, this new behavior broke a Unit-Test for Apache VFS as you can
> see here: https://issues.apache.org/jira/browse/VFS-521
>
> I think this can only be fixed in Throwable by avoiding this
> IllegalArgumentException or by the close() method not using
> try-with-resource.
>
> For reference, according to this changeset other locations are affected
> as well:
> http://hg.openjdk.java.net/jdk8/jdk8/jdk/rev/759aa847dcaf
>
Thanks this bug report, I've created JDK-8042377 to track it. I don't 
think this has come up before, probably because flush and close are more 
likely to throw new exceptions rather than equal (cached) exceptions.

I don't see this issue as driver to changing Throwable to support self 
suppression but we can change BufferedWriter and FilteredOuputStream to 
only add the suppressed exception when they are not equal.

-Alan.