[jira] [Commented] (HADOOP-12529) UserGroupInformation equals method depend on the subject object address

["Vinayakumar B (JIRA)" <ji...@apache.org>]

    [ https://issues.apache.org/jira/browse/HADOOP-12529?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=14984628#comment-14984628 ] 

Vinayakumar B commented on HADOOP-12529:
----------------------------------------

I understand it.

bq. This might imply that caching of proxy users is better handled as an application-specific concern, where that application knows the full lifecycle and usage of those instances, instead of at the core where we don't have that knowledge.
So you mean to say, We leave the current behavior as is, in UGI, let the application cache the instance of proxy user if they want to re-use, based on their usecase. Right.?

> 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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