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From "Walter Su (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HDFS-7980) Incremental BlockReport will dramatically slow down the startup of a namenode
Date Wed, 08 Apr 2015 09:41:13 GMT

     [ https://issues.apache.org/jira/browse/HDFS-7980?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Walter Su updated HDFS-7980:
----------------------------
    Attachment: HDFS-7980.002.patch

> Incremental BlockReport will dramatically slow down the startup of  a namenode
> ------------------------------------------------------------------------------
>
>                 Key: HDFS-7980
>                 URL: https://issues.apache.org/jira/browse/HDFS-7980
>             Project: Hadoop HDFS
>          Issue Type: Bug
>            Reporter: Hui Zheng
>            Assignee: Walter Su
>         Attachments: HDFS-7980.001.patch, HDFS-7980.002.patch
>
>
> In the current implementation the datanode will call the reportReceivedDeletedBlocks()
method that is a IncrementalBlockReport before calling the bpNamenode.blockReport() method.
So in a large(several thousands of datanodes) and busy cluster it will slow down(more than
one hour) the startup of namenode. 
> {code}
> List<DatanodeCommand> blockReport() throws IOException {
>     // send block report if timer has expired.
>     final long startTime = now();
>     if (startTime - lastBlockReport <= dnConf.blockReportInterval) {
>       return null;
>     }
>     final ArrayList<DatanodeCommand> cmds = new ArrayList<DatanodeCommand>();
>     // Flush any block information that precedes the block report. Otherwise
>     // we have a chance that we will miss the delHint information
>     // or we will report an RBW replica after the BlockReport already reports
>     // a FINALIZED one.
>     reportReceivedDeletedBlocks();
>     lastDeletedReport = startTime;
>     .........
>         // Send the reports to the NN.
>     int numReportsSent = 0;
>     int numRPCs = 0;
>     boolean success = false;
>     long brSendStartTime = now();
>     try {
>       if (totalBlockCount < dnConf.blockReportSplitThreshold) {
>         // Below split threshold, send all reports in a single message.
>         DatanodeCommand cmd = bpNamenode.blockReport(
>             bpRegistration, bpos.getBlockPoolId(), reports);
> {code}



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