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Posted to issues@hbase.apache.org by "chenxu (JIRA)" <ji...@apache.org> on 2019/08/07 01:08:00 UTC
[jira] [Comment Edited] (HBASE-22802) Avoid temp ByteBuffer
allocation in FileIOEngine#read
[ https://issues.apache.org/jira/browse/HBASE-22802?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16901597#comment-16901597 ]
chenxu edited comment on HBASE-22802 at 8/7/19 1:07 AM:
--------------------------------------------------------
{quote}so we need to read ByteBuffer one by one for a MultiByteBuff ?
{quote}
yes, we can declare a method like read(FileChannel channel, long offset) in ByteBuff
{quote}When to release the ByteBuff ?
{quote}
I think the ByteBuff will be released in HFileScannerImpl#close, is that right?
and there is no need to share the same refCnt with BucketEntry like what ByteBufferIOEngine to do (code in BucketEntry#wrapAsCacheable)
was (Author: javaman_chen):
bq. so we need to read ByteBuffer one by one for a MultiByteBuff ?
yes, we can declare a method like read(FileChannel channel, long offset) in ByteBuff
bq. When to release the ByteBuff ?
I think the ByteBuff will be released it in HFileScannerImpl#close, is that right?
and there is no need to share the same refCnt with BucketEntry like what ByteBufferIOEngine to do (code in BucketEntry#wrapAsCacheable)
> 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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