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https://issues.apache.org/jira/browse/CASSANDRA-7039?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Branimir Lambov updated CASSANDRA-7039:
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Attachment: 7039.patch
Attached patch updates the lz4-java library to 1.3.0.
> DirectByteBuffer compatible LZ4 methods
> ---------------------------------------
>
> Key: CASSANDRA-7039
> URL: https://issues.apache.org/jira/browse/CASSANDRA-7039
> Project: Cassandra
> Issue Type: Improvement
> Components: Core
> Reporter: Benedict
> Assignee: Branimir Lambov
> Priority: Minor
> Labels: performance
> Fix For: 3.0
>
> Attachments: 7039.patch
>
>
> As we move more things off-heap, it's becoming more and more essential to be
> able to use DirectByteBuffer (or native pointers) in various places.
> Unfortunately LZ4 doesn't currently support this operation, despite being JNI
> based - this means we both have to perform unnecessary copies to de/compress
> data from DBB, but also we can stall GC as any JNI method operating over a
> java array using the GetPrimitiveArrayCritical enters a critical section that
> prevents GC for its duration. This means STWs will be at least as long any
> running compression/decompression (and no GC will happen until they complete,
> so it's additive).
> We should temporarily fork (and then resubmit upstream) jpountz-lz4 to
> support operating over a native pointer, so that we can pass a DBB or a raw
> pointer we have allocated ourselves. This will help improve performance when
> flushing the new offheap memtables, as well as enable us to implement
> CASSANDRA-6726 and finish CASSANDRA-4338.
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