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From "Haohui Mai (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HDFS-6019) Standby NN might not checkpoint when processing the rolling upgrade marker
Date Wed, 26 Feb 2014 08:49:21 GMT

     [ https://issues.apache.org/jira/browse/HDFS-6019?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]

Haohui Mai updated HDFS-6019:
-----------------------------

    Attachment: HDFS-6019.000.patch

> Standby NN might not checkpoint when processing the rolling upgrade marker
> --------------------------------------------------------------------------
>
>                 Key: HDFS-6019
>                 URL: https://issues.apache.org/jira/browse/HDFS-6019
>             Project: Hadoop HDFS
>          Issue Type: Sub-task
>          Components: datanode, ha, hdfs-client, namenode
>            Reporter: Haohui Mai
>            Assignee: Haohui Mai
>         Attachments: HDFS-6019.000.patch
>
>
> {{FsEditlogLoader}} will call {{FSNameSystem#triggerRollbackCheckpoint()}} when processing
the rollback marker, which looks like the following:
> {code}
> void triggerRollbackCheckpoint() {
>   if (standbyCheckpointer != null) {
>     standbyCheckpointer.triggerRollbackCheckpoint();
>   }
> }
> {code}
> There is a race condition where {{standbyCheckpointer}} can be {{null}}, because in the
constructor of the {{NameNode}}, the {{initialize()}} method eventually starts the edit log
tailer, but the standby checkpointer is created in {{HAState#enterState()}}. Therefore, the
checkpointer might not be able to checkpoint when it sees the marker.



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