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https://issues.apache.org/jira/browse/HDFS-4222?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Xiaobo Peng updated HDFS-4222:
------------------------------

    Attachment: hdfs-4222-release-1.0.3.patch
                hdfs-4222-branch-0.23.3.patch

I manually tested the patch on release-1.0.3. Looks like we have some perf gain 
also.

I will test hdfs-4222-branch-0.23.3.patch soon.
                
> NN is unresponsive and lose heartbeats of DNs when Hadoop is configured to 
> use LDAP and LDAP has issues
> -------------------------------------------------------------------------------------------------------
>
>                 Key: HDFS-4222
>                 URL: https://issues.apache.org/jira/browse/HDFS-4222
>             Project: Hadoop HDFS
>          Issue Type: Bug
>          Components: namenode
>    Affects Versions: 0.23.3
>            Reporter: Xiaobo Peng
>            Assignee: Xiaobo Peng
>            Priority: Minor
>         Attachments: hdfs-4222-branch-0.23.3.patch, 
> hdfs-4222-release-1.0.3.patch
>
>
> For Hadoop clusters configured to access directory information by LDAP, the 
> FSNamesystem calls on behave of DFS clients might hang due to LDAP issues 
> (including LDAP access issues caused by networking issues) while holding the 
> single lock of FSNamesystem. That will result in the NN unresponsive and loss 
> of the heartbeats from DNs.
> The places LDAP got accessed by FSNamesystem calls are the instantiation of 
> FSPermissionChecker, which could be moved out of the lock scope since the 
> instantiation does not need the FSNamesystem lock. After the move, a DFS 
> client hang will not affect other threads by hogging the single lock. This is 
> especially helpful when we use separate RPC servers for ClientProtocol and 
> DatanodeProtocol since the calls for DatanodeProtocol do not need to access 
> LDAP. So even if DFS clients hang due to LDAP issues, the NN will still be 
> able to process the requests (including heartbeats) from DNs.

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