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From "Chris Nauroth (JIRA)" <j...@apache.org>
Subject [jira] [Commented] (HADOOP-12529) UserGroupInformation equals method depend on the subject object address
Date Fri, 30 Oct 2015 17:04:27 GMT

    [ https://issues.apache.org/jira/browse/HADOOP-12529?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14982884#comment-14982884
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Chris Nauroth commented on HADOOP-12529:
----------------------------------------

[~vinayrpet], unfortunately, we cannot switch UGI to use value equality instead of reference
equality.  The current behavior is by design as per HADOOP-6670.  Since UGI is mutable, use
of value equality on the {{Subject}} had been causing other problems for the caches that use
UGI as a part of the key.

Looking more closely at HADOOP-6670, I also see that tests were written as part of that patch,
and those tests assert the current behavior.  I expect the changes proposed here would cause
those tests to fail.

> UserGroupInformation equals method depend on the subject object address
> -----------------------------------------------------------------------
>
>                 Key: HADOOP-12529
>                 URL: https://issues.apache.org/jira/browse/HADOOP-12529
>             Project: Hadoop Common
>          Issue Type: Bug
>          Components: security
>    Affects Versions: 2.7.1
>            Reporter: wangwenli
>
>  my question is    why UserGroupInformation equals method depend on the subject object?
>        try below code which is extract from HiveMetaStore:
> {code:title=TestUgi.java|borderStyle=solid}
> UserGroupInformation clientUgi = null;
> UserGroupInformation clientUgi2 = null;
> try {
> clientUgi = UserGroupInformation.createProxyUser("user2", UserGroupInformation.getLoginUser());
> clientUgi2 = UserGroupInformation.createProxyUser("user2", UserGroupInformation.getLoginUser());
> if (clientUgi.equals(clientUgi2)) {
> System.out.println("==");
> } else {
> System.out.println("!=");           //  strangely  this will be hit
> }
> } catch (IOException e1) {
> e1.printStackTrace();
> }
> {code}
>       i found that it is because the equal method from UserGroupInformation is compare
on subject object ref : subject == ((UserGroupInformation) o).subject;  .    
>      as you know,   ipc.Client connect to namenode,   connections.get(ConnectionId) 
  this code will try to reuse the same socket to namenode, but because of ConnectionId's equal
depend on ugi equal, which will cause connections.get(ConnectionId) cann't get the same socket,
  suppose many connect to HiveMetaStore, then many connection to Namenode will established.
>       so my doubts is why UserGroupInformation is compare on subject object ref : subject
== ((UserGroupInformation) o).subject,   it should compare on subject's principal,  am i right?



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