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https://issues.apache.org/jira/browse/HDFS-6019?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jing Zhao resolved HDFS-6019.
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Resolution: Fixed
Hadoop Flags: Reviewed
I've committed this.
> 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, HDFS-6019.001.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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