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https://issues.apache.org/jira/browse/HDFS-4222?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13576388#comment-13576388
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Xiaobo Peng commented on HDFS-4222:
-----------------------------------
Please review my patches. hdfs-4222-branch-0.23.3.patch should be easier to
review. hdfs-4222-release-1.0.3.patch is messy since moving synchronized scopes
result in reformatting.
I think we should enclose all FSPermissionChecker instantiations in "if
(isPermissionEnabled)" blocks as follows,
FSPermissionChecker pc = null;
if (isPermissionEnabled) {
pc = new FSPermissionChecker(fsOwner.getShortUserName(), supergroup);
}
But I have not done so because I want to limit the impact of this changes. If
you know it is totally safe to do such changes, please let me know. Thanks a
lot.
> 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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