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https://issues.apache.org/jira/browse/HDFS-4879?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13761039#comment-13761039
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Hudson commented on HDFS-4879:
------------------------------
FAILURE: Integrated in Hadoop-Mapreduce-trunk #1541 (See
[https://builds.apache.org/job/Hadoop-Mapreduce-trunk/1541/])
HDFS-4879. Add BlockedArrayList collection to avoid CMS full GCs (Contributed
by Todd Lipcon) (cmccabe:
http://svn.apache.org/viewcvs.cgi/?root=Apache-SVN&view=rev&rev=1520667)
* /hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/CHANGES.txt
*
/hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSDirectory.java
*
/hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSEditLogLoader.java
*
/hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/FSNamesystem.java
*
/hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/namenode/INode.java
*
/hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/util/ChunkedArrayList.java
*
/hadoop/common/trunk/hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/util/TestChunkedArrayList.java
> Add "blocked ArrayList" collection to avoid CMS full GCs
> --------------------------------------------------------
>
> Key: HDFS-4879
> URL: https://issues.apache.org/jira/browse/HDFS-4879
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: namenode
> Affects Versions: 3.0.0, 2.0.4-alpha
> Reporter: Todd Lipcon
> Assignee: Todd Lipcon
> Fix For: 2.3.0
>
> Attachments: hdfs-4879.txt, hdfs-4879.txt, hdfs-4879.txt,
> hdfs-4879.txt
>
>
> We recently saw an issue where a large deletion was issued which caused 25M
> blocks to be collected during {{deleteInternal}}. Currently, the list of
> collected blocks is an ArrayList, meaning that we had to allocate a
> contiguous 25M-entry array (~400MB). After a NN has been running for a long
> amount of time, the old generation may become fragmented such that it's hard
> to find a 400MB contiguous chunk of heap.
> In general, we should try to design the NN such that the only large objects
> are long-lived and created at startup time. We can improve this particular
> case (and perhaps some others) by introducing a new List implementation which
> is made of a linked list of arrays, each of which is size-limited (eg to 1MB).
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