[ https://issues.apache.org/jira/browse/HDFS-4461?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13577326#comment-13577326 ]
Harsh J commented on HDFS-4461: ------------------------------- A general memory increase between 1.0 -> 2.0 can also be attributed to the use of the lengthy block pool ID bytes in the file paths? Minor regression, but very clearly present from my experience. > DirectoryScanner: volume path prefix takes up memory for every block that is > scanned > ------------------------------------------------------------------------------------- > > Key: HDFS-4461 > URL: https://issues.apache.org/jira/browse/HDFS-4461 > Project: Hadoop HDFS > Issue Type: Improvement > Affects Versions: 2.0.3-alpha > Reporter: Colin Patrick McCabe > Assignee: Colin Patrick McCabe > Priority: Minor > Attachments: HDFS-4461.002.patch, HDFS-4461.003.patch, > memory-analysis.png > > > In the {{DirectoryScanner}}, we create a class {{ScanInfo}} for every block. > This object contains two File objects-- one for the metadata file, and one > for the block file. Since those File objects contain full paths, users who > pick a lengthly path for their volume roots will end up using an extra > N_blocks * path_prefix bytes per block scanned. We also don't really need to > store File objects-- storing strings and then creating File objects as needed > would be cheaper. This would be a nice efficiency improvement. -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators For more information on JIRA, see: http://www.atlassian.com/software/jira