Haohui Mai created HDFS-6019:
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Summary: 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
Reporter: Haohui Mai
Assignee: Haohui Mai
{{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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