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https://issues.apache.org/jira/browse/CASSANDRA-9608?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16551975#comment-16551975
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Benedict commented on CASSANDRA-9608:
-------------------------------------

I assume this is to handle e.g. the removal of Unsafe.monitorEnter/monitorExit?

A simple improvement to this would be to use a volatile WaitQueue instead of a 
long thread id, that is allocated only on contention, then used as any other 
WaitQueue to manage waiting threads.  This isn't quite as cheap as 
Unsafe.monitorEnter/monitorExit, as the inflated lock is never repurposed until 
flush.  If we wanted, we could probably implement a partially re-usable one, 
which might be applicable elsewhere, or we could have a static 
ConcurrentMap<Key, WaitQueue> to inflate only precisely when needed (though 
this will cost more CPU/memory bandwidth and allocations).

> Support Java 11
> ---------------
>
>                 Key: CASSANDRA-9608
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-9608
>             Project: Cassandra
>          Issue Type: Task
>            Reporter: Robert Stupp
>            Assignee: Robert Stupp
>            Priority: Minor
>             Fix For: 4.x
>
>         Attachments: jdk_9_10.patch
>
>
> This ticket is intended to group all issues found to support Java 9 in the 
> future.
> From what I've found out so far:
> * Maven dependency {{com.sun:tools:jar:0}} via cobertura cannot be resolved. 
> It can be easily solved using this patch:
> {code}
> -        <dependency groupId="net.sourceforge.cobertura" 
> artifactId="cobertura"/>
> +        <dependency groupId="net.sourceforge.cobertura" 
> artifactId="cobertura">
> +          <exclusion groupId="com.sun" artifactId="tools"/>
> +        </dependency>
> {code}
> * Another issue is that {{sun.misc.Unsafe}} no longer contains the methods 
> {{monitorEnter}} + {{monitorExit}}. These methods are used by 
> {{o.a.c.utils.concurrent.Locks}} which is only used by 
> {{o.a.c.db.AtomicBTreeColumns}}.
> I don't mind to start working on this yet since Java 9 is in a too early 
> development phase.



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