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https://issues.apache.org/jira/browse/CASSANDRA-3578?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13223146#comment-13223146
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Michaël Figuière commented on CASSANDRA-3578:
---------------------------------------------

I've used this public domain Java implementation on another project and it was 
behaving pretty well:
[https://github.com/yonik/java_util/blob/master/src/util/hash/MurmurHash3.java]
                
> Multithreaded commitlog
> -----------------------
>
>                 Key: CASSANDRA-3578
>                 URL: https://issues.apache.org/jira/browse/CASSANDRA-3578
>             Project: Cassandra
>          Issue Type: Improvement
>            Reporter: Jonathan Ellis
>            Priority: Minor
>         Attachments: 0001-CASSANDRA-3578.patch, parallel_commit_log_2.patch
>
>
> Brian Aker pointed out a while ago that allowing multiple threads to modify 
> the commitlog simultaneously (reserving space for each with a CAS first, the 
> way we do in the SlabAllocator.Region.allocate) can improve performance, 
> since you're not bottlenecking on a single thread to do all the copying and 
> CRC computation.
> Now that we use mmap'd CommitLog segments (CASSANDRA-3411) this becomes 
> doable.
> (moved from CASSANDRA-622, which was getting a bit muddled.)

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