Jinglun created HDFS-14964:
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Summary: Race between RouterUpdateService and RouterAdmin -setQuota
Key: HDFS-14964
URL: https://issues.apache.org/jira/browse/HDFS-14964
Project: Hadoop HDFS
Issue Type: Bug
Reporter: Jinglun
Assignee: Jinglun
There is a race condition between RouterUpdateService and RouterAdmin
-setQuota.
Supposing the mount table is:
M1: /dir-1 ns0:/dir-1 \{nsQuota, ssQuota}
# RouterUpdateService is scheduled. It finds the nsUsage of M1 is changed and
wants to update it at RouterQuotaUpdateService#147.
# Before RouterUpdateService updates, a RouterAdmin use -setQuota and update
the Mount Entry Quota.
# RouterAdmin -setQuota executes successfully and the quota is updated.
# RouterUpdateService is re-scheduled. It doesn't know the mount entry on zk
has already been updated. So it continue to update the quota usage and hence
overwrite RouterAdmin's change.
I think a possible solution would be not letting RouterUpdateService to update
mount entry on zk(It will still update usage in cache). Let RouterAdmin be the
only entrance to update mount entry on zk. Even one Router restarts the
RouterUpdateService would compute and update the usage in cache so not getting
usage from zk won't be a big problem.
I wrote a unit test to show the race case.
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