[ https://issues.apache.org/jira/browse/HDFS-14296?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
BELUGA BEHR updated HDFS-14296: ------------------------------- Status: Patch Available (was: Open) > Prefer ArrayList over LinkedList in VolumeScanner > ------------------------------------------------- > > Key: HDFS-14296 > URL: https://issues.apache.org/jira/browse/HDFS-14296 > Project: Hadoop HDFS > Issue Type: Improvement > Components: datanode > Affects Versions: 3.2.0 > Reporter: BELUGA BEHR > Assignee: BELUGA BEHR > Priority: Minor > Attachments: HDFS-14296.1.patch > > > {quote}The {{size}}, {{isEmpty}}, {{get}}, {{set}}, {{iterator}}, and > {{listIterator}} operations run in constant time. - ArrayList > {quote} > However, for a {{LinkedList}}, the entire list must be traversed to get to > the desired index. > Like > [Here|https://github.com/apache/hadoop/blob/trunk/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/VolumeScanner.java#L384] > Most of the time, the List is being iterated, which is quicker over a > primitive array than walking a LinkedList. > There is one place where an item is removed, potentially from the middle of > the list > [here|https://github.com/apache/hadoop/blob/trunk/hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/VolumeScanner.java#L736] > but the speed of removing from the middle of the list isn't bad; it's a > system native array shift, and it only happens on the off chance that a block > pool is removed from the DataNode. -- This message was sent by Atlassian JIRA (v7.6.3#76005) --------------------------------------------------------------------- To unsubscribe, e-mail: hdfs-issues-unsubscr...@hadoop.apache.org For additional commands, e-mail: hdfs-issues-h...@hadoop.apache.org