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https://issues.apache.org/jira/browse/HDFS-5587?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13837413#comment-13837413
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Jing Zhao commented on HDFS-5587:
---------------------------------
The patch looks good overall. Some comments:
# When we have duplicated user/group names, instead of terminating the whole
process, I think it will be better to rethrow the IOException and let
upper-level application handle the exception.
{code}
+ LOG.fatal("Can't update maps:" + e);
+ terminate(1, e);
{code}
# We can check the detailed exception message after catching the exception in
the following code:
{code}
+ try {
+ IdUserGroup.updateMapInternal(uMap, "user", GET_ALL_USERS_CMD, ":");
+ fail("didn't detect the duplicate name");
+ } catch (IOException e) {
+ }
{code}
> add debug information when NFS fails to start with duplicate user or group
> names
> --------------------------------------------------------------------------------
>
> Key: HDFS-5587
> URL: https://issues.apache.org/jira/browse/HDFS-5587
> Project: Hadoop HDFS
> Issue Type: Improvement
> Components: nfs
> Reporter: Brandon Li
> Assignee: Brandon Li
> Priority: Minor
> Attachments: HDFS-5587.001.patch
>
>
> When the host provides duplicate user or group names, NFS will not start and
> print errors like the following:
> {noformat}
> ... ...
> 13/11/25 18:11:52 INFO nfs3.Nfs3Base: registered UNIX signal handlers for
> [TERM, HUP, INT]
> Exception in thread "main" java.lang.IllegalArgumentException: value already
> present: s-iss
> at com.google.common.base.Preconditions.checkArgument(Preconditions.java:115)
> at
> com.google.common.collect.AbstractBiMap.putInBothMaps(AbstractBiMap.java:112)
> at com.google.common.collect.AbstractBiMap.put(AbstractBiMap.java:96)
> at com.google.common.collect.HashBiMap.put(HashBiMap.java:85)
> at
> org.apache.hadoop.nfs.nfs3.IdUserGroup.updateMapInternal(IdUserGroup.java:85)
> at org.apache.hadoop.nfs.nfs3.IdUserGroup.updateMaps(IdUserGroup.java:110)
> at org.apache.hadoop.nfs.nfs3.IdUserGroup.<init>(IdUserGroup.java:54)
> at
> org.apache.hadoop.hdfs.nfs.nfs3.RpcProgramNfs3.<init>(RpcProgramNfs3.java:172)
> at
> org.apache.hadoop.hdfs.nfs.nfs3.RpcProgramNfs3.<init>(RpcProgramNfs3.java:164)
> at org.apache.hadoop.hdfs.nfs.nfs3.Nfs3.<init>(Nfs3.java:41)
> at org.apache.hadoop.hdfs.nfs.nfs3.Nfs3.main(Nfs3.java:52)
> 13/11/25 18:11:54 INFO nfs3.Nfs3Base: SHUTDOWN_MSG:
> ... ...
> {noformat}
> The reason NFS should not start is that, HDFS (non-kerberos cluster) uses
> name as the only way to identify a user. On some linux box, it could have two
> users with the same name but different user IDs. Linux might be able to work
> fine with that most of the time. However, when NFS gateway talks to HDFS,
> HDFS accepts only user name. That is, from HDFS' point of view, these two
> different users are the same user even though they are different on the Linux
> box.
> The duplicate names on Linux systems sometimes is because of some legacy
> system configurations, or combined name services.
> Regardless, NFS gateway should print some help information so the user can
> understand the error and the remove the duplicated names before NFS restart.
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