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From "Suresh Srinivas (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (HDFS-4222) NN is unresponsive and lose heartbeats of DNs when Hadoop is configured to use LDAP and LDAP has issues
Date Wed, 20 Feb 2013 01:24:12 GMT

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

Suresh Srinivas updated HDFS-4222:
----------------------------------

    Attachment: HDFS-4222.patch

Changes in this patch:
# Introduced {{FSNamesystem#fsOwnerShortUserName}} to avoid getting short username from a
UGI {{FSNamesystem#fsOwner}} every time {{FSPermissionChecker}} is used.
# Made changes to create FSPermissionChecker outside the FSNamesystem read and write lock.
This is along the lines of the work Xiaobo has done.
# Documented the synchronization semantics in FSPermissionChecker and made some members final.

                
> 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.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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