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https://issues.apache.org/jira/browse/HDFS-13898?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16612499#comment-16612499
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Chao Sun commented on HDFS-13898:
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Thanks [~xkrogen] for taking a look!
bq. I also don't really understand why we need to tweak the number of DNs if
the BlockManager is mocked anyway?
Yes we don't need to change {{MiniQJMHACluster}} - I did that mainly because it
already has a {{setNumNameNodes}} method. Will change back.
bq. I also don't really understand why we need to tweak the number of DNs if
the BlockManager is mocked anyway?
This is to bypass the exception:
"org.apache.hadoop.ipc.RemoteException(java.io.IOException): Requested
replication factor of 0 is less than the required minimum of 1" when calling
{{dfs.createNewFile(testPath);}}. This is not related to the BlockManager I
think.
bq. 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 ...
Hmm. For the first approach using {{addBlockLocation}}, we have to provide the
{{BlockInfo}} instance for the specific test file, is that right? Looking at
{{FSDirStatAndListingOp#getBlockLocations}}, it requires non-trivial code to
come up with all the parameters to get the required {{BlockInfo}}. Wonder if
you have any suggestion.
Not sure how {{corruptBlockOnDataNodes}} will work in this case - we are trying
to
> 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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