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https://issues.apache.org/jira/browse/HBASE-22031?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16803304#comment-16803304
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Xu Cang commented on HBASE-22031:
---------------------------------
There are 2 ways can possibly cause issues.
Original holder of this object modifies the 'tables' or new object who is
pointing to the shared object can modify it.
I am still open to discuss this with you, waiting for your new review as you
mentioned above. Thanks.
> Provide RSGroupInfo with a new constructor using shallow copy
> -------------------------------------------------------------
>
> Key: HBASE-22031
> URL: https://issues.apache.org/jira/browse/HBASE-22031
> Project: HBase
> Issue Type: Improvement
> Components: rsgroup
> Reporter: Xiang Li
> Assignee: Xiang Li
> Priority: Minor
> Attachments: HBASE-22031.master.000.patch,
> HBASE-22031.master.001.patch, HBASE-22031.master.002.patch
>
>
> As for org.apache.hadoop.hbase.rsgroup.RSGroupInfo, the following constructor
> performs deep copies on both servers and tables inputed.
> {code:title=hbase-common/src/main/java/org/apache/hadoop/hbase/rsgroup/RSGroupInfo.java.java|borderStyle=solid}
> RSGroupInfo(String name, SortedSet<Address> servers, SortedSet<TableName>
> tables) {
> this.name = name;
> this.servers = (servers == null) ? new TreeSet<>() : new TreeSet<>(servers);
> this.tables = (tables == null) ? new TreeSet<>() : new TreeSet<>(tables);
> }
> {code}
> The constructor of TreeSet is heavy and I think it is better to have a new
> constructor with shallow copy and it could be used at least in
> {code:title=hbase-rsgroup/src/main/java/org/apache/hadoop/hbase/rsgroup/RSGroupInfoManagerImpl.java|borderStyle=solid}
> private synchronized void refresh(boolean forceOnline) throws IOException {
> ...
> groupList.add(new RSGroupInfo(RSGroupInfo.DEFAULT_GROUP,
> getDefaultServers(), orphanTables));
> ...
> {code}
> It is not needed to allocate new TreeSet to deep copy the output of
> getDefaultServers() and orphanTables, both of which are allocated in the near
> context and not updated in the code followed. So it is safe to make a shadow
> copy here.
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