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dhruba borthakur commented on HDFS-1295: ---------------------------------------- Hi Matt, thanks for the info about HDFS-1147. I closed it as a duplicate of this one. > this approach can be made to work in the presence of corrupt replicas, that > will be great. can somebody pl elaborate on what possible issue a corrupt-replica might cause? > Improve namenode restart times by short-circuiting the first block reports > from datanodes > ----------------------------------------------------------------------------------------- > > Key: HDFS-1295 > URL: https://issues.apache.org/jira/browse/HDFS-1295 > Project: Hadoop HDFS > Issue Type: Improvement > Components: name-node > Reporter: dhruba borthakur > Assignee: dhruba borthakur > Fix For: 0.22.0 > > Attachments: shortCircuitBlockReport_1.txt > > > The namenode restart is dominated by the performance of processing block > reports. On a 2000 node cluster with 90 million blocks, block report > processing takes 30 to 40 minutes. The namenode "diffs" the contents of the > incoming block report with the contents of the blocks map, and then applies > these diffs to the blocksMap, but in reality there is no need to compute the > "diff" because this is the first block report from the datanode. > This code change improves block report processing time by 300%. -- This message is automatically generated by JIRA. - You can reply to this email to add a comment to the issue online.