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https://issues.apache.org/jira/browse/DERBY-4963?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13001117#comment-13001117
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Knut Anders Hatlen commented on DERBY-4963:
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Thanks for writing the release note, Rick. It is clear and looks correct for
the most part. The one thing I believe is inaccurate, is the sentence
"Solaris/JDK5 is one of these platforms." I don't think Solaris is affected by
this change, at least not on JDK 5.
I think the only platforms affected are those that suffered from DERBY-1, which
are some old releases of Java 1.4.2 and Java 5 on Mac OS/X and FreeBSD (and
possibly other BSDs). And, looking at the code, it probably also affects a code
path taken by all JVMs at version 1.4.0 and 1.4.1, but I'm not sure if we still
support those variants of 1.4 or if we require 1.4.2 now.
Dag, does that sound correct, or did I garble things?
> Revert to FileDescriptor#sync from FileChannel#force to improve interrupt
> resilience
> ------------------------------------------------------------------------------------
>
> Key: DERBY-4963
> URL: https://issues.apache.org/jira/browse/DERBY-4963
> Project: Derby
> Issue Type: Improvement
> Components: Store
> Reporter: Dag H. Wanvik
> Assignee: Dag H. Wanvik
> Fix For: 10.8.0.0
>
> Attachments: derby-4963-1.diff, derby-4963-1.stat, derby-4963-2.diff,
> derby-4963-2.stat, releaseNote.html
>
>
> FileChannel.force is interruptable, and we really don't want to be
> interrupted when we flush the log file. Happily, on most platforms, we use
> the "rws"/"rwd" file open mask which makes the writes thjemselves
> synchronized, so no subsequent explicit file level sync is needed anyway.
> DirFile4#getRandowmAccessFile should use plain DirRandomAccessFile instead of
> the current DirRandomAccessFile4. This will make StorageRandomAccessFile#sync
> map to FileDescriptor#sync instead of FileChannel#force (also for NIO
> supporting platforms).
> Since FileDescriptor#sync does not allow synching file data only (it also
> synchronizes metadata), those platforms which do not support write
> synchronization will experience a performance drop, but this is the price we
> have to pay to survive interrupts without shutting down the database on those
> platforms.
> Users which experience this as a problem, should update to a newer JVM which
> does support "rws"/"rwd" in the mode argument to java.io.RandomAccessFile
> (http://download.oracle.com/javase/6/docs/api/java/io/RandomAccessFile.html#RandomAccessFile(java.io.File,%20java.lang.String).
> Cf. also discussion on
> https://issues.apache.org/jira/browse/DERBY-4741?focusedCommentId=12977862&page=com.atlassian.jira.plugin.system.issuetabpanels%3Acomment-tabpanel#action_12977862
> .
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