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https://issues.apache.org/jira/browse/HBASE-5926?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13278147#comment-13278147
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nkeywal commented on HBASE-5926:
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bq. You should look at the javadoc that is created from your src. Its going to
be a jumble. Check it out. You need a little bit of html in there at least for
your list of strategy dependencies.
Done.
bq. What is the filecontent? We don't need any, right? The name of the file is
enough?
We need the content. For the regionserver, the content is the znode path. For
the master it's the full ServerName (stringified).
bq. This should be boolean rather than int? Or is it returned to shell? If so,
should say so in the comment: "+ * @return if done returns 0 else -1."
Done.
bq. Is CleanZNode a good name? How about ZNodeCleaner or ZNodeClearer or
CrashZNodeCleaner?
Renamed to ZNodeClearer
bq. I think in HMasterCommandLine, should be start|stop|clear so it fits format
of the other commands.
Done.
bq. In MasterAddressTracker, can you get the znode sequence id and only delete
if the sequence id matches?
We store the full ServerName so if there is a restart we will see it. But maybe
you're speaking about the znode version? Because I looked at the zk api, and
with the version we could remove totally the race condition...
> Delete the master znode after a master crash
> --------------------------------------------
>
> Key: HBASE-5926
> URL: https://issues.apache.org/jira/browse/HBASE-5926
> Project: HBase
> Issue Type: Improvement
> Components: master, scripts
> Affects Versions: 0.96.0
> Reporter: nkeywal
> Assignee: nkeywal
> Priority: Minor
> Fix For: 0.96.0
>
> Attachments: 5926.v6.patch, 5926.v8.patch, 5926.v9.patch
>
>
> This is the continuation of the work done in HBASE-5844.
> But we can't apply exactly the same strategy: for the region server, there is
> a znode per region server, while for the master & backup master there is a
> single znode for both.
> So if we apply the same strategy as for a regionserver, we may have this
> scenario:
> 1) Master starts
> 2) Backup master starts
> 3) Master dies
> 4) ZK detects it
> 5) Backup master receives the update from ZK
> 6) Backup master creates the new master node and become the main master
> 7) Previous master script continues
> 8) Previous master script deletes the master node in ZK
> 9) => issue: we deleted the node just created by the new master
> This should not happen often (usually the znode will be deleted soon enough),
> but it can happen.
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