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https://issues.apache.org/jira/browse/HBASE-2248?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Todd Lipcon updated HBASE-2248:
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Attachment: readownwrites-lost.patch
Here's a test case patch (on top of yours) which should illustrate the issue.
It fails every time for me on a dual core box:
Didnt read own writes expected:<395> but was:<394>
junit.framework.AssertionFailedError: Didnt read own writes expected:<395> but
was:<394>
at
org.apache.hadoop.hbase.regionserver.TestMemStore$ReadOwnWritesTester.internalRun(TestMemStore.java:293)
at
org.apache.hadoop.hbase.regionserver.TestMemStore$ReadOwnWritesTester.run(TestMemStore.java:268)
> 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
> Fix For: 0.20.4
>
> Attachments: HBASE-2248-demonstrate-previous-impl-bugs.patch,
> HBASE-2248-ryan.patch, hbase-2248.gc, HBASE-2248.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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