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https://issues.apache.org/jira/browse/HBASE-22802?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16901223#comment-16901223
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Zheng Hu commented on HBASE-22802:
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Sounds good to do this. Few questions:
1. The ByteBuffAllocator#allocate(length) will get a ByteBuff (composited by
multi nio ByteBuffers), while the fileChannel#read (from JDK) can only accept
nio ByteBuffers, so we need to read ByteBuffer one by one for a MultiByteBuff
? I think so.
2. When to release the ByteBuff ? Seems we can release the ByteBuff once the
Cacheable#release it.
Thanks.
> Avoid temp ByteBuffer allocation in FileIOEngine#read
> -----------------------------------------------------
>
> Key: HBASE-22802
> URL: https://issues.apache.org/jira/browse/HBASE-22802
> Project: HBase
> Issue Type: Improvement
> Components: BucketCache
> Reporter: chenxu
> Priority: Major
> Attachments: profile_mem_alloc.png
>
>
> a temp ByteBuffer was allocated each time FileIOEngine#read was called
> {code:java}
> public Cacheable read(BucketEntry be) throws IOException {
> long offset = be.offset();
> int length = be.getLength();
> Preconditions.checkArgument(length >= 0, "Length of read can not be less
> than 0.");
> ByteBuffer dstBuffer = ByteBuffer.allocate(length);
> ...
> }
> {code}
> we can avoid this by use of ByteBuffAllocator#allocate(length) after
> HBASE-21879
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