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https://issues.apache.org/jira/browse/HBASE-5088?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13181637#comment-13181637
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Lars Hofhansl commented on HBASE-5088:
--------------------------------------
In a quick local test (on pseudo distributed mode) I was able to reproduce the
slow down with ConcurrentSkipListMap that Jieshan has reported, in my case the
slowdown was even worse (runtime went up from ~12.5s to ~17.5 - everything is
faster in local mode, so a constant slowdown will have a larger proportional
impact).
With the last patch (sync Object) I have not seen any slowdown using the same
test. So I think this is good to go a soon as HadoopQA confirms.
> A concurrency issue on SoftValueSortedMap
> -----------------------------------------
>
> Key: HBASE-5088
> URL: https://issues.apache.org/jira/browse/HBASE-5088
> Project: HBase
> Issue Type: Bug
> Components: client
> Affects Versions: 0.90.4, 0.94.0
> Reporter: Jieshan Bean
> Assignee: Jieshan Bean
> Priority: Critical
> Fix For: 0.92.0, 0.90.6
>
> Attachments: 5088-final.txt, 5088-syncObj.txt,
> 5088-useMapInterfaces.txt, 5088.generics.txt, HBase-5088-90.patch,
> HBase-5088-trunk.patch, HBase5088-90-replaceSoftValueSortedMap.patch,
> HBase5088-90-replaceTreeMap.patch, HBase5088-trunk-replaceTreeMap.patch,
> HBase5088Reproduce.java, PerformanceTestResults.png
>
>
> SoftValueSortedMap is backed by a TreeMap. All the methods in this class are
> synchronized. If we use this method to add/delete elements, it's ok.
> But in HConnectionManager#getCachedLocation, it use headMap to get a view
> from SoftValueSortedMap#internalMap. Once we operate
> on this view map(like add/delete) in other threads, a concurrency issue may
> occur.
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