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https://issues.apache.org/jira/browse/HADOOP-12475?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14959678#comment-14959678
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Hudson commented on HADOOP-12475:
---------------------------------
FAILURE: Integrated in Hadoop-Mapreduce-trunk #2488 (See
[https://builds.apache.org/job/Hadoop-Mapreduce-trunk/2488/])
HADOOP-12475. Replace guava Cache with ConcurrentHashMap for caching (sjlee:
rev 8d2d3eb7bb938cc06ea3cc74040cfe0be13a2ba8)
* hadoop-common-project/hadoop-common/CHANGES.txt
*
hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/ipc/Client.java
> Replace guava Cache with ConcurrentHashMap for caching Connection in ipc
> Client
> -------------------------------------------------------------------------------
>
> Key: HADOOP-12475
> URL: https://issues.apache.org/jira/browse/HADOOP-12475
> Project: Hadoop Common
> Issue Type: Sub-task
> Components: conf, io, ipc
> Reporter: Walter Su
> Assignee: Walter Su
> Fix For: 2.8.0
>
> Attachments: HADOOP-12475.01.patch, HADOOP-12475.02.patch,
> HADOOP-12475.03.patch
>
>
> quote [~daryn] from HADOOP-11772:
> {quote}
> CacheBuilder is obscenely expensive for concurrent map, and it requires
> generating unnecessary garbage even just to look up a key. Replace it with
> ConcurrentHashMap.
> I identified this issue that impaired my own perf testing under load. The
> slowdown isn't just the sync. It's the expensive of Connection's ctor
> stalling other connections. The expensive of ConnectionId#equals causes
> delays. Synch'ing on connections causes unfair contention unlike a sync'ed
> method. Concurrency simply hides this.
> {quote}
> BTW, guava Cache is heavyweight. Per local test, ConcurrentHashMap has better
> overal performance.
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