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Walter Su commented on HDFS-7784: --------------------------------- In my testing, the memory usage doesn't grow. GC doesn't get worse. I do use a small buffer to avoid frequently lock()/unlock(), How will (small)buffer affect gc? Deserialization still create the same amount of garbage, it's a matter of speed. > load fsimage in parallel > ------------------------ > > Key: HDFS-7784 > URL: https://issues.apache.org/jira/browse/HDFS-7784 > Project: Hadoop HDFS > Issue Type: Improvement > Components: namenode > Reporter: Walter Su > Assignee: Walter Su > Priority: Minor > Attachments: HDFS-7784.001.patch, test-20150213.pdf > > > When single Namenode has huge amount of files, without using federation, the > startup/restart speed is slow. The fsimage loading step takes the most of the > time. fsimage loading can seperate to two parts, deserialization and object > construction(mostly map insertion). Deserialization takes the most of CPU > time. So we can do deserialization in parallel, and add to hashmap in serial. > It will significantly reduce the NN start time. -- This message was sent by Atlassian JIRA (v6.3.4#6332)