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Uma Maheswara Rao G commented on HDFS-2486: ------------------------------------------- This patch addresses the second comment. After concluding the last comment, that can be handled as separate JIRA(subtask), if required and also depending on code change. > Review issues with UnderReplicatedBlocks > ---------------------------------------- > > Key: HDFS-2486 > URL: https://issues.apache.org/jira/browse/HDFS-2486 > Project: Hadoop HDFS > Issue Type: Task > Components: name-node > Affects Versions: 0.23.0 > Reporter: Steve Loughran > Assignee: Uma Maheswara Rao G > Priority: Minor > Attachments: HDFS-2486.patch > > > Here are some things I've noted in the UnderReplicatedBlocks class that > someone else should review and consider if the code is correct. If not, they > are easy to fix. > remove(Block block, int priLevel) is not synchronized, and as the inner > classes are not, there is a risk of race conditions there. > some of the code assumes that getPriority can return the value LEVEL, and if > so does not attempt to queue the blocks. As this return value is not > currently possible, those checks can be removed. > The queue gives priority to blocks whose replication count is less than a > third of its expected count over those that are "normally under replicated". > While this is good for ensuring that files scheduled for large replication > are replicated fast, it may not be the best strategy for maintaining data > integrity. For that it may be better to give whichever blocks have only two > replicas priority over blocks that may, for example, already have 3 out of 10 > copies in the filesystem. -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators: https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa For more information on JIRA, see: http://www.atlassian.com/software/jira