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https://issues.apache.org/jira/browse/HBASE-13814?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14578280#comment-14578280
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Lars Hofhansl edited comment on HBASE-13814 at 6/9/15 4:06 AM:
---------------------------------------------------------------
[~cuijianwei], can you explain in a few words how this fixes the problem. I
think I get it: master.getServerName() does not have the right server, right?
I think we can simplify:
{code}
+ if (!regions.containsKey(region) || (serverName = regions.get(region))
== null) {
{code}
To
{code}
+ if ((serverName = regions.get(region)) == null) {
{code}
Can we move:
{code}
+ ServerName serverName = null;
{code}
Inside the synchronized?
was (Author: lhofhansl):
[~cuijianwei], can you explain in a few words how this fixes the problem. I
think I get it: master.getServerName() does not have the right server, right?
I think we can simplify:
{code}
+ if (!regions.containsKey(region) || (serverName = regions.get(region))
== null) {
{code}
To
{code}
+ if ((serverName = regions.get(region)) == null) {
{code}
Can we move:
{code}
+ ServerName serverName = null;
{code}
Inside the synchronized.
> AssignmentManager does not write the correct server name into Zookeeper when
> unassign region
> --------------------------------------------------------------------------------------------
>
> Key: HBASE-13814
> URL: https://issues.apache.org/jira/browse/HBASE-13814
> Project: HBase
> Issue Type: Bug
> Components: Region Assignment
> Affects Versions: 0.94.27
> Reporter: cuijianwei
> Priority: Minor
> Attachments: HBASE-13814-0.94-v1.patch
>
>
> When moving region, the region will firstly be unassigned from corresponding
> region server by the method AssignmentManager#unassign(). AssignmentManager
> will write the region info and the server name into Zookeeper by the
> following code:
> {code}
> versionOfClosingNode = ZKAssign.createNodeClosing(
> master.getZooKeeper(), region, master.getServerName());
> {code}
> It seems that the AssignmentManager misuses the master's name as the server
> name. If the ROOT region is being moved and the region server holding the
> ROOT region is just crashed. The Master will try to start a
> MetaServerShutdownHandler if the server is judged as holding meta region. The
> judgment will be done by the method AssignmentManager#isCarryingRegion, and
> the method will firstly check the server name in Zookeeper:
> {code}
> ServerName addressFromZK = (data != null && data.getOrigin() != null) ?
> data.getOrigin() : null;
> if (addressFromZK != null) {
> // if we get something from ZK, we will use the data
> boolean matchZK = (addressFromZK != null &&
> addressFromZK.equals(serverName));
> {code}
> The wrong server name from Zookeeper will make the server not be judged as
> holding the ROOT region. Then, the master will start a ServerShutdownHandler.
> Unlike MetaServerShutdownHandler, the ServerShutdownHandler won't assign ROOT
> region firstly, making the ROOT region won't be assigned forever. In our test
> environment, we encounter this problem when moving ROOT region and stopping
> the region server concurrently.
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