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https://issues.apache.org/jira/browse/HDFS-13898?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16611150#comment-16611150
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Erik Krogen commented on HDFS-13898:
------------------------------------
Nice find [~csun]! The change to production code LGTM. For the tests:
* You don't need to make the changes to {{MiniQJMHACluster}}. You can set the
number of DataNodes like:
{code}
builder.getDfsBuilder().numDataNodes(3);
{code}
I also don't really understand why we need to tweak the number of DNs if the
BlockManager is mocked anyway?
* I don't really find the BlockManager mocking to be very clean. I think we
should be able to achieve something similar by using a real BlockManager, but
injecting some fake blocks:
{code}
NameNodeAdapter.getNamesystem(namenodes[2]).getBlockManager().addBlockCollection(...)
{code}
or creating real blocks, but then corrupting them:
{code}
dfsCluster.corruptBlockOnDataNodes()
{code}
> Throw retriable exception for getBlockLocations when ObserverNameNode is in
> safemode
> ------------------------------------------------------------------------------------
>
> Key: HDFS-13898
> URL: https://issues.apache.org/jira/browse/HDFS-13898
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Reporter: Chao Sun
> Assignee: Chao Sun
> Priority: Major
> Attachments: HDFS-13898-HDFS-12943.000.patch
>
>
> When ObserverNameNode is in safe mode, {{getBlockLocations}} may throw safe
> mode exception if the given file doesn't have any block yet.
> {code}
> try {
> checkOperation(OperationCategory.READ);
> res = FSDirStatAndListingOp.getBlockLocations(
> dir, pc, srcArg, offset, length, true);
> if (isInSafeMode()) {
> for (LocatedBlock b : res.blocks.getLocatedBlocks()) {
> // if safemode & no block locations yet then throw safemodeException
> if ((b.getLocations() == null) || (b.getLocations().length == 0)) {
> SafeModeException se = newSafemodeException(
> "Zero blocklocations for " + srcArg);
> if (haEnabled && haContext != null &&
> haContext.getState().getServiceState() ==
> HAServiceState.ACTIVE) {
> throw new RetriableException(se);
> } else {
> throw se;
> }
> }
> }
> }
> {code}
> It only throws {{RetriableException}} for active NN so requests on observer
> may just fail.
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