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https://issues.apache.org/jira/browse/HBASE-17738?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16094468#comment-16094468
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ramkrishna.s.vasudevan edited comment on HBASE-17738 at 7/20/17 10:27 AM:
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The Math.round() was causing the issue. In case we need to create 25 buffers
and 16 threads are available, then perthreadCount by doing round off was
creating 2 bytebuffers and the last threads had to create -5 (which is wrong)
and also per thread it was creating more than what is required.
So now we do a Math.floor() and round it off to int. Creating this case with a
test case is difficult so I just reproduced the above case by making
ByteBufferarray non final and mocking the available thread count. So this test
will fail based on the number of available threads in the system and not on any
other system if the resulting calculation yields better result (based on the
number of threads).
was (Author: ram_krish):
The Math.round() was causing the issue. In case we need to create 25 buffers
and 16 threads are available, then perthreadCount by doing round off was
creating 2 bytebuffers and the last threads had to create -5 (which is wrong)
and also per thread it was creating more than what is required.
So now we do a Math.floor() and round it off to int. Creating this case with a
test case is difficult so I just reproduced the above case by making
ByteBufferarray non final and mocking the available thread count. So this test
will fail based on the number of available threads in the system and not on any
other system if the resulting calculation yields better result.
> BucketCache startup is slow
> ---------------------------
>
> Key: HBASE-17738
> URL: https://issues.apache.org/jira/browse/HBASE-17738
> Project: HBase
> Issue Type: Sub-task
> Components: BucketCache
> Affects Versions: 2.0.0
> Reporter: stack
> Assignee: ramkrishna.s.vasudevan
> Fix For: 2.0.0, 2.0.0-alpha-2
>
> Attachments: HBASE-17738_10.patch, HBASE-17738_2.patch,
> HBASE-17738_2.patch, HBASE-17738_3.patch, HBASE-17738_4.patch,
> HBASE-17738_5_withoutUnsafe.patch, HBASE-17738_6_withoutUnsafe.patch,
> HBASE-17738_8.patch, HBASE-17738_9.patch, HBASE-17738_log.patch,
> HBASE-17738.patch
>
>
> If you set bucketcache size at 64G say and then start hbase, it takes a long
> time. Can we do the allocations in parallel and not inline with the server
> startup?
> Related, prefetching on a bucketcache is slow. Speed it up.
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