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https://issues.apache.org/jira/browse/HDFS-17156?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17755265#comment-17755265
]
ASF GitHub Bot commented on HDFS-17156:
---------------------------------------
simbadzina commented on PR #5951:
URL: https://github.com/apache/hadoop/pull/5951#issuecomment-1681305358
I've created a unit test here:
https://github.com/simbadzina/hadoop/pull/1/commits/d216bfe8c5f506f08263cf490479a0398b097f05
```
/**
* Verify that stateID is received into call before
* call is notified.
* @throws IOException
*/
@Test(timeout=60000)
public void testReceiveStateBeforeCallerNotification() throws IOException {
AtomicBoolean stateReceived = new AtomicBoolean(false);
AlignmentContext alignmentContext = Mockito.mock(AlignmentContext.class);
Mockito.doAnswer((Answer<Void>) invocation -> {
Thread.sleep(1000);
stateReceived.set(true);
return null;
}).when(alignmentContext)
.receiveResponseState(any(RpcHeaderProtos.RpcResponseHeaderProto.class));
final Client client = Mockito.spy(new Client(LongWritable.class, conf));
final TestServer server = new TestServer(1, false);
try {
InetSocketAddress addr = NetUtils.getConnectAddress(server);
server.start();
call(client, new LongWritable(RANDOM.nextLong()), addr,
0, conf, alignmentContext);
Assert.assertTrue(stateReceived.get());
} finally {
client.stop();
server.stop();
}
}
```
> mapreduce job encounters java.io.IOException
> --------------------------------------------
>
> Key: HDFS-17156
> URL: https://issues.apache.org/jira/browse/HDFS-17156
> Project: Hadoop HDFS
> Issue Type: Bug
> Components: rbf
> Reporter: Chunyi Yang
> Assignee: Chunyi Yang
> Priority: Minor
> Labels: Observer, RBF, pull-request-available
>
> While executing a mapreduce job in an environment utilizing Router-Based
> Federation with Observer read enabled, there is an estimated 1% chance of
> encountering the following error.
> {code:java}
> "java.io.IOException: Resource
> hdfs://XXXX/user/XXXX/.staging/job_XXXXXX/.tez/application_XXXXXX/tez-conf.pb
> changed on src filesystem - expected: \"2023-07-07T12:41:16.801+0900\", was:
> \"2023-07-07T12:41:16.822+0900\", current time:
> \"2023-07-07T12:41:22.386+0900\"",
> {code}
> This error happens in function verifyAndCopy inside FSDownload.java when
> nodemanager tries to download a file right after the file has been written to
> the HDFS. The write operation runs on active namenode and read operation runs
> on observer namenode as expected.
> The edits file and hdfs-audit files indicate that the expected timestamp
> mentioned in the error message aligns with the OP_CLOSE MTIME of the
> 'tez-conf.pb' file (which is correct). However, the actual timestamp
> retrieved from the read operation corresponds to the OP_ADD MTIME of the
> target 'tez-conf.pf' file (which is incorrect). This inconsistency suggests
> that the observer namenode responds to the client before its edits file is
> updated with the latest stateId.
> Further troubleshooting has revealed that during write operations, the router
> responds to the client before receiving the latest stateId from the active
> namenode. Consequently, the outdated stateId is then used in the subsequent
> read operation on the observer namenode, leading to inaccuracies in the
> information provided by the observer namenode.
> To resolve this issue, it is essential to ensure that the router sends a
> response to the client only after receiving the latest stateId from the
> active namenode.
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