[
https://issues.apache.org/jira/browse/HBASE-22504?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Nick Dimiduk reopened HBASE-22504:
----------------------------------
>From the 2.3.0RC0, looks like this change introduced a breach of our
>compatibility guidelines. The method {{findCommonPrefix}} needs to be restored
>(and optionally marked as deprecated).
> Optimize the MultiByteBuff#get(ByteBuffer, offset, len)
> -------------------------------------------------------
>
> Key: HBASE-22504
> URL: https://issues.apache.org/jira/browse/HBASE-22504
> Project: HBase
> Issue Type: Sub-task
> Components: BucketCache
> Reporter: Zheng Hu
> Assignee: Zheng Hu
> Priority: Major
> Fix For: 3.0.0-alpha-1, 2.3.0
>
> Attachments: HBASE-22504.HBASE-21879.v01.patch
>
>
> In HBASE-22483, we saw that the BucketCacheWriter thread was quite busy
> [^BucketCacheWriter-is-busy.png], the flame graph also indicated that the
> ByteBufferArray#internalTransfer cost ~6% CPU (see
> [async-prof-pid-25042-cpu-1.svg|https://issues.apache.org/jira/secure/attachment/12970294/async-prof-pid-25042-cpu-1.svg]).
> because we used the hbase.ipc.server.allocator.buffer.size=64KB, each
> HFileBlock will be backend by a MultiByteBuff: one 64KB offheap ByteBuffer
> and one small heap ByteBuffer.
> The path is depending on the MultiByteBuff#get(ByteBuffer, offset, len) now:
> {code:java}
> RAMQueueEntry#writeToCache
> |--> ByteBufferIOEngine#write
> |--> ByteBufferArray#internalTransfer
> |--> ByteBufferArray$WRITER
> |--> MultiByteBuff#get(ByteBuffer, offset, len)
> {code}
> While the MultiByteBuff#get impl is simple and crude now, can optimze this
> implementation:
> {code:java}
> @Override
> public void get(ByteBuffer out, int sourceOffset,
> int length) {
> checkRefCount();
> // Not used from real read path actually. So not going with
> // optimization
> for (int i = 0; i < length; ++i) {
> out.put(this.get(sourceOffset + i));
> }
> }
> {code}
>
--
This message was sent by Atlassian Jira
(v8.3.4#803005)
