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https://issues.apache.org/jira/browse/HDFS-8688?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14630715#comment-14630715
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Walter Su commented on HDFS-8688:
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bq. There are several other places that call blockHasEnoughRacks directly only
if there is no pending replications for that block. Maybe we can do the same
for addStoredBlock case in addition to the current patch. In that way, we make
sure blockHasEnoughRacks will be called only when there is enough liveReplicas.
Agree.
If pendingReplication not null, we don't need check blockHasEnoughRacks(). We
wait pendingReplication to be finished, and we check blockHasEnoughRacks()
again later.
That's the appropriate way.
---------
bq. There are several other places that call blockHasEnoughRacks directly only
if there is no pending replications for that block. Maybe we can do the same
for addStoredBlock case in addition to the current patch. In that way, we make
sure blockHasEnoughRacks will be called only when there is enough liveReplicas.
1. >...if there is pendingReplications, NN still calls blockHasEnoughRacks() in
addStoredBlock.
Yes. Good catch!
2. >...we can do the same for addStoredBlock ...
No, we don't have to.
{code}
2703 if (!isNeededReplication(storedBlock, fileReplication,
numCurrentReplica)) {
2704 neededReplications.remove(storedBlock, numCurrentReplica,
2705 num.decommissionedAndDecommissioning(), fileReplication);
2706 } else {
2707 updateNeededReplications(storedBlock, curReplicaDelta, 0);
2708 }
{code}
You must be confused why line 2703 uses {{numCurrentReplica}} but not live
nodes. In fact the logic is correct. Because line 2704 is
neededReplications.remove(..). If the number of racks already meet, it's
natrual to remove from neededReplications.
line 2707 take effect only if in safemode.
In general, addStoredBlock will NOT add block to neededReplications. We don't
have to change anything about it.
> replace shouldCheckForEnoughRacks with hasClusterEverBeenMultiRack
> ------------------------------------------------------------------
>
> Key: HDFS-8688
> URL: https://issues.apache.org/jira/browse/HDFS-8688
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Reporter: Walter Su
> Assignee: Walter Su
> Attachments: HDFS-8688.01.patch, HDFS-8688.02.patch
>
>
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