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https://issues.apache.org/jira/browse/HBASE-15885?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15299373#comment-15299373
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Guanghao Zhang commented on HBASE-15885:
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Yes, it changes the behavior when get exception in
computeHDFSBlocksDistribution(fs). As I profile the region close/open process,
computeHDFSBlocksDistribution take about 10ms. Reducing the hdfs block
distribution calculation three times may save 3 * 10ms for region not serving
time.
> Compute StoreFile HDFS Blocks Distribution when needed
> ------------------------------------------------------
>
> Key: HBASE-15885
> URL: https://issues.apache.org/jira/browse/HBASE-15885
> Project: HBase
> Issue Type: Improvement
> Components: HFile
> Affects Versions: 2.0.0
> Reporter: Guanghao Zhang
> Attachments: HBASE-15885.patch
>
>
> Now when open a StoreFileReader, it always need to compute HDFS blocks
> distribution. But when balance a region, it will increase the region not
> serving time. Because it need first close region on rs A, then open it on rs
> B. When close region, it first preFlush, then flush the new update to a new
> store file. The new store file will first be flushed to tmp directory, then
> move it to column family directory. These need open StoreFileReader twice
> which means it need compute HDFS blocks distribution twice. When open region
> on rs B, it need open StoreFileReader and compute HDFS blocks distribution
> too. So when balance a region, it need compute HDFS blocks distribution three
> times for per new store file. This will increase the region not serving time
> and we don't need compute HDFS blocks distribution when close a region.
> The related three methods in HStore.
> 1. validateStoreFile(...)
> 2. commitFile(...)
> 3. openStoreFiles(...)
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