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https://issues.apache.org/jira/browse/HDDS-427?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16609951#comment-16609951
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Anu Engineer commented on HDDS-427:
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{quote} Not all of them may view container with no replica as something which
warrants an exception from api itself.
{quote}
The Ozone/HDDS assumes that a container has the requisite number of replicas.
Not having the replica is an error state. So the normal path should be that we
should throw an error.
{quote} In some of those cases it is perfectly normal case
{quote}
Yes, in most cases this is the normal path.
{quote}For example during SCM chill mode a container might not have any replica
reported initially
{quote}
Chill mode is a special case, it is the time when the cluster is booting up and
we may not have container reports. So shouldn't the Chill Mode manager handle
this special case, as appropriate?
{quote}Similarly during container report handling if no replicas are found for
given container ContainerReportHandler should log the message and move on as
ReplicationManager can't do anything in that specific case
{quote}
Absolutely not. If the replicas are missing, it is up to replica manager to
deal with that issue. The appropriate course of action, if it is creating
alerting events, logging or whatever should be done, should be done by the
replica manager. This is a case where Container report handler should catch the
error and send across to Replica Manager – probably with logging. But deciding
that information will not go to ReplicaManager is a no go. Returning null to
flag an error state can lead to users of API ignoring this error. If we throw
an exception, we are flagging and error which the caller cannot ignore and
therefore if the user decides that it an okay error state; for example, Chill
Mode, User can catch this error and ignore it.
Due to the above reasons I am -1 on this patch.
> For containers with no replica ContainerStateMap#getContainerReplicas should
> return empty map
> ---------------------------------------------------------------------------------------------
>
> Key: HDDS-427
> URL: https://issues.apache.org/jira/browse/HDDS-427
> Project: Hadoop Distributed Data Store
> Issue Type: Improvement
> Reporter: Ajay Kumar
> Assignee: Ajay Kumar
> Priority: Major
> Attachments: HDDS-427.00.patch
>
>
> Callers of API ContainerStateMap#getContainerReplicas should be allowed to
> decide if its violation of some condition (when there are no replicas,
> warranting exception) instead of it being implicit to every caller. Instead
> ContainerStateMap#getContainerReplicas should return empty map for no
> replicas. Callers can decide if no replicas for given container is a volition
> of business condition. Throwing exception in this API also results in a
> subtle bug in ContainerReportHandler where exception for one container may
> result in whole container list being skipped.
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