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https://issues.apache.org/jira/browse/HDFS-17232?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17786498#comment-17786498
]
ASF GitHub Bot commented on HDFS-17232:
---------------------------------------
simbadzina commented on code in PR #6208:
URL: https://github.com/apache/hadoop/pull/6208#discussion_r1394785317
##########
hadoop-hdfs-project/hadoop-hdfs-rbf/src/test/java/org/apache/hadoop/hdfs/server/federation/MiniRouterDFSCluster.java:
##########
@@ -253,6 +253,19 @@ public FileSystem
getFileSystemWithObserverReadProxyProvider() throws IOExceptio
return DistributedFileSystem.get(observerReadConf);
}
+ public FileSystem getFileSystemWithConfiguredFailoverProxyProvider()
throws IOException {
+ conf.set(DFS_NAMESERVICES,
+ conf.get(DFS_NAMESERVICES)+ ",router-service");
+ conf.set(DFS_HA_NAMENODES_KEY_PREFIX + ".router-service", "router1");
+ conf.set(DFS_NAMENODE_RPC_ADDRESS_KEY+ ".router-service.router1",
+ getFileSystemURI().toString());
+ conf.set(HdfsClientConfigKeys.Failover.PROXY_PROVIDER_KEY_PREFIX
+ + "." + "router-service",
ConfiguredFailoverProxyProvider.class.getName());
+ DistributedFileSystem.setDefaultUri(conf, "hdfs://router-service");
+
+ return DistributedFileSystem.get(conf);
+ }
Review Comment:
`getFileSystemWithConfiguredFailoverProxyProvider` and
`getFileSystemWithObserverReadProxyProvider()` share the same configuration,
beside the proxy provider. You can separate shared config these one into a
separate function, then just set the proxy provider.
> RBF: Fix NoNamenodesAvailableException for a long time, when use observer
> -------------------------------------------------------------------------
>
> Key: HDFS-17232
> URL: https://issues.apache.org/jira/browse/HDFS-17232
> Project: Hadoop HDFS
> Issue Type: Bug
> Reporter: Jian Zhang
> Assignee: Jian Zhang
> Priority: Major
> Labels: pull-request-available
> Attachments: HDFS-17232.001.patch
>
>
> *Describe*
> I solved the NoNamenodesAvailableException for a long time, when failover
> without using observer, but when using observer, there are still many
> problems.
> # When the observer fails and there is no active namenode at this time,
> even if we can rotate the cache, the next request will shuffle the observer
> namenode to the front of the cache due to the use of the observer, so retry
> will still send the request to the failed observer node.
> # If there are multiple observers, and an exception occurs when accessing an
> observer and there is no active namenode at this time, a
> NoNamenodesAvailableException will be caused and the server will try again.
> However, since using the observer will put the observer node at the front of
> the cache, it may still fail.
> # When there are multiple observers, one of which is unavailable and there
> is no active namenode at this time, we should continue to try the next
> observer, so that the currently unavailable observer can be marked as
> unavailable, and subsequent requests can avoid the unavailable observer.
> # If it is due to an illegal operation, that is, even if the operation is
> sent to the active namenode, an exception will occur, resulting in
> NoNamenodesAvailableException. If the cache is rotated at this time, the next
> normal request will be sent to the namenode that is indeed the standby,
> causing an error in the legal request. , so illegal operations should not
> rotate the cache.
>
> Detailed bug description: HDFS-17166
>
> - *case 1:*
> * router's cache : [ observer-1(problematic), standby-2, standby-3(actually
> active) ]
> * client read -> observer-1 throw NoNamenodesAvailableException ->
> rotate the cache -> [ standby-2, standby-3(actually
> active),observer-1(problematic) ]
> * client retry read -> shuffleObserverNN -> [ observer-1(problematic),
> standby-2, standby-3(actually active) ] -> observer-1 throw
> NoNamenodesAvailableException -> rotate the cache -> [ standby-2,
> standby-3(actually active),observer-1(problematic) ]
> * *.....*
> * client (reties > max.attempts ) -> Read failed
>
> - *case 2:*
> * router's cache : [ observer-1(problematic), observer-2, standby-3,
> standby-4(actually active) ]
> * client read -> observer-1 throw NoNamenodesAvailableException ->
> rotate the cache -> [ observer-2, standby-3, standby-4(actually
> active),observer-1(problematic) ]
> * client retry read -> shuffleObserverNN -> [ observer-1(problematic),
> observer-2, standby-3, standby-4(actually active) ] (may happen) ->
> observer-1 throw NoNamenodesAvailableException -> rotate the cache -> [
> observer-2, standby-3, standby-4(actually active),observer-1(problematic) ]
> * *.....*
> * client may (reties > max.attempts ) -> Read failed
> - *case 3:*
> * router's cache : [ standby-1, standby-2(actually active) ]
> * client request -> standby-1 throw NoNamenodesAvailableException ->
> rotate the cache -> [ standby-2(actually active),standby-1 ]
> * client retry request -> standby-2(actually active) success
> * client Illegal request -> standby-2(actually active) throw
> NoNamenodesAvailableException -> rotate the cache -> [standby1,
> standby-2(actually active) ]
> * client legal request -> standby1 throw NoNamenodesAvailableException
> failed
> *How to reproduce*
> I have provided unit tests:TestNoNamenodesAvailableLongTime
> You can use the original code and run my new unit tests to reproduce the
> above problems.
>
>
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