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https://issues.apache.org/jira/browse/HBASE-23887?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17044740#comment-17044740
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Danil Lipovoy commented on HBASE-23887:
---------------------------------------
>>Then the naming hbase.lru.cache.data.block.percent is not good, it is
>>confusing.
Ok, what would be better?
>>One case: if client happens to read 198 many times, then 198 will never get
>>cached because of the rule.
It is good point! We can easy provide special condition for that extreme cases
- just skip the new logic for IN_MEMORY tables:
{code:java}
if (cacheDataBlockPercent != 100 && buf.getBlockType().isData() && !inMemory)
{{code}
If someone read really often (in our case block evicts by few seconds because
heavy read) and need full cached data, he can use this option.
>>Another one extreme case: all offset last 2 digits just between [00, 85]
>>(assuming 85 set), then BC will cache them all anyway...
Please clarify, do you mean that blocks could be not evenly distributed?
If it is the point, I could collect statistics for millions requests and we
will know it for sure.
>>YCSB is a good benchmark tool,
Agree, I use it for tests. Now I loaded 1 bln records into 1 table 64 regions
all in on 1 RS and read it by YCSB. Below the results.
1. The old way:
[OVERALL], RunTime(ms), 45470
[OVERALL], Throughput(ops/sec), 21992.522542335606
[TOTAL_GCS_PS_Scavenge], Count, 8
[TOTAL_GC_TIME_PS_Scavenge], Time(ms), 740
[TOTAL_GC_TIME_%_PS_Scavenge], Time(%), 1.627446668132835
[TOTAL_GCS_PS_MarkSweep], Count, 1
[TOTAL_GC_TIME_PS_MarkSweep], Time(ms), 31
[TOTAL_GC_TIME_%_PS_MarkSweep], Time(%), 0.06817681988124037
[TOTAL_GCs], Count, 9
[TOTAL_GC_TIME], Time(ms), 771
[TOTAL_GC_TIME_%], Time(%), 1.6956234880140753
[READ], Operations, 1000000
[READ], AverageLatency(us), 882.532253
[READ], MinLatency(us), 137
[READ], MaxLatency(us), 599039
[READ], 95thPercentileLatency(us), 765
[READ], 99thPercentileLatency(us), 949
[READ], Return=OK, 1000000
[CLEANUP], Operations, 40
[CLEANUP], AverageLatency(us), 1560.15
[CLEANUP], MinLatency(us), 1
[CLEANUP], MaxLatency(us), 61599
[CLEANUP], 95thPercentileLatency(us), 32
[CLEANUP], 99thPercentileLatency(us), 61599
2. The new way:
[OVERALL], RunTime(ms), 34467
[OVERALL], Throughput(ops/sec), 29013.25905939014
[TOTAL_GCS_PS_Scavenge], Count, 9
[TOTAL_GC_TIME_PS_Scavenge], Time(ms), 104
[TOTAL_GC_TIME_%_PS_Scavenge], Time(%), 0.3017378942176575
[TOTAL_GCS_PS_MarkSweep], Count, 1
[TOTAL_GC_TIME_PS_MarkSweep], Time(ms), 32
[TOTAL_GC_TIME_%_PS_MarkSweep], Time(%), 0.09284242899004845
[TOTAL_GCs], Count, 10
[TOTAL_GC_TIME], Time(ms), 136
[TOTAL_GC_TIME_%], Time(%), 0.3945803232077059
[READ], Operations, 1000000
[READ], AverageLatency(us), 661.87457
[READ], MinLatency(us), 145
[READ], MaxLatency(us), 261759
[READ], 95thPercentileLatency(us), 808
[READ], 99thPercentileLatency(us), 955
[READ], Return=OK, 1000000
[CLEANUP], Operations, 40
[CLEANUP], AverageLatency(us), 2626.25
[CLEANUP], MinLatency(us), 1
[CLEANUP], MaxLatency(us), 104511
[CLEANUP], 95thPercentileLatency(us), 26
[CLEANUP], 99thPercentileLatency(us), 104511
> BlockCache performance improve
> ------------------------------
>
> Key: HBASE-23887
> URL: https://issues.apache.org/jira/browse/HBASE-23887
> Project: HBase
> Issue Type: Improvement
> Components: BlockCache, Performance
> Reporter: Danil Lipovoy
> Priority: Minor
> Attachments: cmp.png
>
>
> Hi!
> I first time here, correct me please if something wrong.
> I want propose how to improve performance when data in HFiles much more than
> BlockChache (usual story in BigData). The idea - caching only part of DATA
> blocks. It is good becouse LruBlockCache starts to work and save huge amount
> of GC. See the picture in attachment with test below. Requests per second is
> higher, GC is lower.
>
> The key point of the code:
> Added the parameter: *hbase.lru.cache.data.block.percent* which by default =
> 100
>
> But if we set it 0-99, then will work the next logic:
>
>
> {code:java}
> public void cacheBlock(BlockCacheKey cacheKey, Cacheable buf, boolean
> inMemory) {
> if (cacheDataBlockPercent != 100 && buf.getBlockType().isData())
> if (cacheKey.getOffset() % 100 >= cacheDataBlockPercent)
> return;
> ...
> // the same code as usual
> }
> {code}
>
>
> Descriptions of the test:
> 4 nodes E5-2698 v4 @ 2.20GHz, 700 Gb Mem.
> 4 RegionServers
> 4 tables by 64 regions by 1.88 Gb data in each = 600 Gb total (only FAST_DIFF)
> Total BlockCache Size = 48 Gb (8 % of data in HFiles)
> Random read in 20 threads
>
> I am going to make Pull Request, hope it is right way to make some
> contribution in this cool product.
>
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