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https://issues.apache.org/jira/browse/HBASE-15959?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15319905#comment-15319905
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Jingcheng Du commented on HBASE-15959:
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bq. Across runs, same cell (ie. same key) may or may not be considered mob
reference cell. here. This at least happens with row keys 0 - 4 (which got
compacted earlier)
Thanks a lot, Appy.
I think this is design on purpose for this Test?
In this test, it tries to verify the correctness that how mob cells are moved
between store files and mob files.
before the 1st compaction, the threshold is 0, it means all of the cells are
considered as mob ones, and there are only reference cells in store files.
In the 1st compaction, the threshold is changed to 100 which is larger than the
value size of each mob cells. In this compaction, the cells are moved back to
store files.
In the scan after the 1st compaction, all the cells are the real ones, not
reference ones.
In the 2nd compaction, the threshold is changed to 0, and all cells are moved
to mob files from store files. And in the second scan, the cells are the
reference ones.
> Fix flaky test TestRegionServerMetrics.testMobMetrics
> -----------------------------------------------------
>
> Key: HBASE-15959
> URL: https://issues.apache.org/jira/browse/HBASE-15959
> Project: HBase
> Issue Type: Bug
> Reporter: Appy
> Assignee: huaxiang sun
>
> It flakes
> [here|https://github.com/apache/hbase/blob/b557f0bec62a48753e5d01d7a47f3c9e5a6b3ee8/hbase-server/src/test/java/org/apache/hadoop/hbase/regionserver/TestRegionServerMetrics.java#L460].
> There are two weird things i identified:
> 1. In second compaction,
> [scanner|https://github.com/apache/hbase/blob/b557f0bec62a48753e5d01d7a47f3c9e5a6b3ee8/hbase-server/src/main/java/org/apache/hadoop/hbase/mob/DefaultMobStoreCompactor.java#L173]
> has 10 storefiles. Shouldn't there be 6? 5 from recent flushes and 1 from
> earlier compaction. Probably because mob cleaner doesn't clean old hfiles.
> Does this needs fixing?
> 2. Across runs, same cell (ie. same key) may or may not be considered mob
> reference cell.
> [here|https://github.com/apache/hbase/blob/b557f0bec62a48753e5d01d7a47f3c9e5a6b3ee8/hbase-server/src/main/java/org/apache/hadoop/hbase/mob/DefaultMobStoreCompactor.java#L213].
> This at least happens with row keys 0 - 4 (which got compacted earlier).
> [~jmhsieh] Any ideas why this would happen.
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