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https://issues.apache.org/jira/browse/HDFS-13811?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16704423#comment-16704423
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Yiqun Lin commented on HDFS-13811:
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Hi [~dibyendu_hadoop],
{quote}
I haven't change the existing logic for getQuotaUsage. I have added a check to
verify the quota cache value for the requested mount entry, if the cache is
null, it will try to refresh the cache for that mount entry only.
{quote}
I suppose we can extract this as a new function and be called in
{{getQuotaUsage(String path)}}.
{quote}
If we don't use updateQuotaCache flag, from
RouterQuotaUpdateService#periodicInvoke getQuotaSetMountTables will eventually
call getQuotaUsage, which will again call periodicInvoke and it will go into an
infinite loop. That's why updateQuotaCache flag is required.
{quote}
I am not fully understanding these. I don't mean we must hard-coded the flag
{{updateQuotaCache}} value as value in {{GetMountTableEntriesRequest}}. As I
see {{getMountTableEntries(boolean updateQuotaCache)}} is used only by
{{getQuotaSetMountTables}}. And then quota service passes a false value to
{{getQuotaSetMountTables}}. And no others places use this function. So I
suggest to remove the parameter in function.
Please feel free to attach next patch now.
> RBF: Race condition between router admin quota update and periodic quota
> update service
> ---------------------------------------------------------------------------------------
>
> Key: HDFS-13811
> URL: https://issues.apache.org/jira/browse/HDFS-13811
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Reporter: Dibyendu Karmakar
> Assignee: Dibyendu Karmakar
> Priority: Major
> Attachments: HDFS-13811-000.patch, HDFS-13811-HDFS-13891-000.patch
>
>
> If we try to update quota of an existing mount entry and at the same time
> periodic quota update service is running on the same mount entry, it is
> leading the mount table to _inconsistent state._
> Here transactions are:
> A - Quota update service is fetching mount table entries.
> B - Quota update service is updating the mount table with current usage.
> A' - User is trying to update quota using admin cmd.
> and the transaction sequence is [ A A' B ]
> quota update service is updating the mount table with old quota value.
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