Benedict created CASSANDRA-7039:
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Summary: 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
Priority: Minor
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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