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https://issues.apache.org/jira/browse/LUCENE-6989?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15735844#comment-15735844
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Uwe Schindler commented on LUCENE-6989:
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With this patch the class loads again, although it does not work:
{noformat}
[junit4] Suite: org.apache.lucene.store.TestMultiMMap
[junit4] IGNOR/A 0.03s | TestMultiMMap.testDeleteFile
[junit4] > Assumption #1: test requires a jre that supports unmapping:
Unmapping is not supported on this platform, because internal Java APIs are not
compatible to this Lucene version:
java.lang.reflect.InaccessibleObjectException: Unable to make public
jdk.internal.ref.Cleaner java.nio.DirectByteBuffer.cleaner() accessible: module
java.base does not "opens java.nio" to unnamed module @4823fcdd
{noformat}
> Implement MMapDirectory unmapping for coming Java 9 changes
> -----------------------------------------------------------
>
> Key: LUCENE-6989
> URL: https://issues.apache.org/jira/browse/LUCENE-6989
> Project: Lucene - Core
> Issue Type: Task
> Components: core/store
> Reporter: Uwe Schindler
> Assignee: Uwe Schindler
> Labels: Java9
> Fix For: 6.0
>
> Attachments: LUCENE-6989-disable5x.patch,
> LUCENE-6989-disable5x.patch, LUCENE-6989-fixbuild148.patch,
> LUCENE-6989-v2.patch, LUCENE-6989.patch, LUCENE-6989.patch,
> LUCENE-6989.patch, LUCENE-6989.patch
>
>
> Originally, the sun.misc.Cleaner interface was declared as "critical API" in
> [JEP 260|http://openjdk.java.net/jeps/260 ]
> Unfortunately the decission was changed in favor of a oficially supported
> {{java.lang.ref.Cleaner}} API. A side effect of this change is to move all
> existing {{sun.misc.Cleaner}} APIs into a non-exported package. This causes
> our forceful unmapping to no longer work, because we can get the cleaner
> instance via reflection, but trying to invoke it will throw one of the new
> Jigsaw RuntimeException because it is completely inaccessible. This will make
> our forceful unmapping fail. There are also no changes in Garbage collector,
> the problem still exists.
> For more information see this [mailing list
> thread|http://mail.openjdk.java.net/pipermail/core-libs-dev/2016-January/thread.html#38243].
> This commit will likely be done, making our unmapping efforts no longer
> working. Alan Bateman is aware of this issue and will open a new issue at
> OpenJDK to allow forceful unmapping without using the now private
> sun.misc.Cleaner. The idea is to let the internal class sun.misc.Cleaner
> implement the Runable interface, so we can simply cast to runable and call
> the run() method to unmap. The code would then work. This will lead to minor
> changes in our unmapper in MMapDirectory: An instanceof check and casting if
> possible.
> I opened this issue to keep track and implement the changes as soon as
> possible, so people will have working unmapping when java 9 comes out.
> Current Lucene versions will no longer work with Java 9.
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