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https://issues.apache.org/jira/browse/HBASE-2248?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12855130#action_12855130
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Andrew Purtell commented on HBASE-2248:
---------------------------------------
When I run alpha3 on top of 0.20 head I see delete test failures in :
Testcase: testWeirdCacheBehaviour took 81.599 sec
Testcase: testFilterAcrossMutlipleRegions took 47.8 sec
Testcase: testSuperSimple took 18.15 sec
Testcase: testFilters took 15.781 sec
Testcase: testSimpleMissing took 16.448 sec
Testcase: testSingleRowMultipleFamily took 16.686 sec
Testcase: testNull took 21.443 sec
Testcase: testVersions took 18.169 sec
Testcase: testVersionLimits took 15.861 sec
Testcase: testDeletes took 15.837 sec
Caused an ERROR
null
java.lang.NullPointerException
at org.apache.hadoop.hbase.client.TestClient.testDeletes(TestClient.java
:1608)
Testcase: testJIRAs took 46.161 sec
Need more detail?
> Provide new non-copy mechanism to assure atomic reads in get and scan
> ---------------------------------------------------------------------
>
> Key: HBASE-2248
> URL: https://issues.apache.org/jira/browse/HBASE-2248
> Project: Hadoop HBase
> Issue Type: Bug
> Affects Versions: 0.20.3
> Reporter: Dave Latham
> Priority: Blocker
> Fix For: 0.20.4
>
> Attachments: HBASE-2248-demonstrate-previous-impl-bugs.patch,
> HBASE-2248-GetsAsScans3.patch, HBASE-2248-rr-alpha1.txt,
> HBASE-2248-rr-alpha2.txt, HBASE-2248-rr-alpha3.txt, HBASE-2248-ryan.patch,
> hbase-2248.gc, HBASE-2248.patch, hbase-2248.txt, readownwrites-lost.2.patch,
> readownwrites-lost.patch, Screen shot 2010-02-23 at 10.33.38 AM.png,
> threads.txt
>
>
> HBASE-2037 introduced a new MemStoreScanner which triggers a
> ConcurrentSkipListMap.buildFromSorted clone of the memstore and snapshot when
> starting a scan.
> After upgrading to 0.20.3, we noticed a big slowdown in our use of short
> scans. Some of our data repesent a time series. The data is stored in time
> series order, MR jobs often insert/update new data at the end of the series,
> and queries usually have to pick up some or all of the series. These are
> often scans of 0-100 rows at a time. To load one page, we'll observe about
> 20 such scans being triggered concurrently, and they take 2 seconds to
> complete. Doing a thread dump of a region server shows many threads in
> ConcurrentSkipListMap.biuldFromSorted which traverses the entire map of key
> values to copy it.
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