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https://issues.apache.org/jira/browse/HBASE-15433?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15194845#comment-15194845
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Jianwei Cui commented on HBASE-15433:
-------------------------------------
Reasonable for this case IMO. It seems there are other issues when concurrently
restoring snapshots for the same table. We need to keep the
{{checkAndUpdateNamespaceRegionQuota}} the same order before and after
{{restoreSnapshot}} among concurrent restore requests. For example, beofre
{{restoreSnapshot}}, if clientA invoked {{checkAndUpdateNamespaceRegionQuota}}
ahead of clientB, then after {{restoreSnapshot}}, we need to make sure clientA
also invoked {{checkAndUpdateNamespaceRegionQuota}} ahead of clientB?
In the document of
[HBASE-12439|https://issues.apache.org/jira/browse/HBASE-12439], it seems the
CloneSnapshotHandler/RestoreSnapshotHandler will be rewritten by procedure v2?
After that, we can keep the quota updating sync with
CloneSnapshot/RestoreSnapshot steps and rollbacks. Currently, without steps and
rollbacks, RestoreSnapshotHandler may not update the quota information
correctly. Therefore, I think we can still keep the quota updating in
{{SnapshotManager}} before procedure v2 rewritten? For concurrent request
issues, we can add some comments in the code to explain the problem?
> SnapshotManager#restoreSnapshot not update table and region count quota
> correctly when encountering exception
> -------------------------------------------------------------------------------------------------------------
>
> Key: HBASE-15433
> URL: https://issues.apache.org/jira/browse/HBASE-15433
> Project: HBase
> Issue Type: Bug
> Components: snapshots
> Affects Versions: 2.0.0
> Reporter: Jianwei Cui
> Attachments: HBASE-15433-trunk-v1.patch, HBASE-15433-trunk-v2.patch,
> HBASE-15433-trunk.patch
>
>
> In SnapshotManager#restoreSnapshot, the table and region quota will be
> checked and updated as:
> {code}
> try {
> // Table already exist. Check and update the region quota for this
> table namespace
> checkAndUpdateNamespaceRegionQuota(manifest, tableName);
> restoreSnapshot(snapshot, snapshotTableDesc);
> } catch (IOException e) {
>
> this.master.getMasterQuotaManager().removeTableFromNamespaceQuota(tableName);
> LOG.error("Exception occurred while restoring the snapshot " +
> snapshot.getName()
> + " as table " + tableName.getNameAsString(), e);
> throw e;
> }
> {code}
> The 'checkAndUpdateNamespaceRegionQuota' will fail if regions in the snapshot
> make the region count quota exceeded, then, the table will be removed in the
> 'catch' block. This will make the current table count and region count
> decrease, following table creation or region split will succeed even if the
> actual quota is exceeded.
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