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https://issues.apache.org/jira/browse/HBASE-15959?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15320076#comment-15320076
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Jingcheng Du commented on HBASE-15959:
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Oops, my mistake. The compacted files are not directly removed any more in the
code of master branch (instead it uses a region server chore to do that). Not
sure why it needs this after compaction. But this can lead to mob issues just
in this case.
Let me give a example, we have three store files, sf#1 has a seqId as 5, sf#2
has a seqId as 6, and sf#3 has a seqId as 7, after compaction we have a new
store file sf#4 who has a a seqId as 6. In normal cases, sF#1-3 are removed
from the store files in the context (not from file system).
After the {{region.initialize()}}, some of cells come from sf#3 replace the
cells in sf#4, this breaks the test. But the WAL is supposed to guarantee the
correctness after region is restarted. But the WAL is not replayed in
{{region.initialize()}} in this case, the number of found HLogs is 0,
> 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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