[
https://issues.apache.org/jira/browse/DERBY-4963?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13001345#comment-13001345
]
Knut Anders Hatlen commented on DERBY-4963:
-------------------------------------------
My comment about 1.4.0 and 1.4.1 was based on this comment in LogToFile:
* Note: Why logging system support file sync and write sync ?
* Note : The reason to support file and write sync of logs is
* there was no support to do write sync until jdk1.4 and then
* there was write sync jvm bug in jdk1.4.1, only in jdk1.4.2 write
* sync(rws and rwd modes) mechanism can be used correctly.
* Default in JVMS >= jdk1.4.2 is write sync(see the boot method for
jvm checks).
And in DirStorageFactory4:
private static final boolean rwsOK = JVMInfo.JDK_ID >=
JVMInfo.J2SE_142;
> 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
> .
--
This message is automatically generated by JIRA.
-
For more information on JIRA, see: http://www.atlassian.com/software/jira
