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https://issues.apache.org/jira/browse/HDFS-15651?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
Wei-Chiu Chuang updated HDFS-15651:
-----------------------------------
Fix Version/s: 3.3.1
> Client could not obtain block when DN CommandProcessingThread exit
> ------------------------------------------------------------------
>
> Key: HDFS-15651
> URL: https://issues.apache.org/jira/browse/HDFS-15651
> Project: Hadoop HDFS
> Issue Type: Bug
> Reporter: Yiqun Lin
> Assignee: Aiphago
> Priority: Major
> Fix For: 3.3.1, 3.4.0
>
> Attachments: HDFS-15651.001.patch, HDFS-15651.002.patch,
> HDFS-15651.patch
>
>
> In our cluster, we applied the HDFS-14997 improvement.
> We find one case that CommandProcessingThread will exit due to OOM error.
> OOM error was caused by our one abnormal application that running on this DN
> node.
> {noformat}
> 2020-10-18 10:27:12,604 ERROR
> org.apache.hadoop.hdfs.server.datanode.DataNode: Command processor
> encountered fatal exception and exit.
> java.lang.OutOfMemoryError: unable to create new native thread
> at java.lang.Thread.start0(Native Method)
> at java.lang.Thread.start(Thread.java:717)
> at
> java.util.concurrent.ThreadPoolExecutor.addWorker(ThreadPoolExecutor.java:957)
> at
> java.util.concurrent.ThreadPoolExecutor.execute(ThreadPoolExecutor.java:1367)
> at
> org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetAsyncDiskService.execute(FsDatasetAsyncDiskService.java:173)
> at
> org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetAsyncDiskService.deleteAsync(FsDatasetAsyncDiskService.java:222)
> at
> org.apache.hadoop.hdfs.server.datanode.fsdataset.impl.FsDatasetImpl.invalidate(FsDatasetImpl.java:2005)
> at
> org.apache.hadoop.hdfs.server.datanode.BPOfferService.processCommandFromActive(BPOfferService.java:671)
> at
> org.apache.hadoop.hdfs.server.datanode.BPOfferService.processCommandFromActor(BPOfferService.java:617)
> at
> org.apache.hadoop.hdfs.server.datanode.BPServiceActor$CommandProcessingThread.processCommand(BPServiceActor.java:1247)
> at
> org.apache.hadoop.hdfs.server.datanode.BPServiceActor$CommandProcessingThread.access$1000(BPServiceActor.java:1194)
> at
> org.apache.hadoop.hdfs.server.datanode.BPServiceActor$CommandProcessingThread$3.run(BPServiceActor.java:1299)
> at
> org.apache.hadoop.hdfs.server.datanode.BPServiceActor$CommandProcessingThread.processQueue(BPServiceActor.java:1221)
> at
> org.apache.hadoop.hdfs.server.datanode.BPServiceActor$CommandProcessingThread.run(BPServiceActor.java:1208)
> {noformat}
> Here the main point is that CommandProcessingThread crashed will lead a very
> bad impact. All the NN response commands will not be processed by DN side.
> We enabled the block token to access the data, but here the DN command
> DNA_ACCESSKEYUPDATE is not processed on time by DN. And then we see lots of
> Sasl error due to key expiration in DN log:
> {noformat}
> javax.security.sasl.SaslException: DIGEST-MD5: IO error acquiring password
> [Caused by org.apache.hadoop.security.token.SecretManager$InvalidToken: Can't
> re-compute password for block_token_identifier (expiryDate=xxx, keyId=xx,
> userId=xxx, blockPoolId=xxxx, blockId=xxx, access modes=[READ]), since the
> required block key (keyID=xxx) doesn't exist.]
> {noformat}
>
> For the impact in client side, our users receive lots of 'could not obtain
> block' error with BlockMissingException.
> CommandProcessingThread is a critical thread, it should always be running.
> {code:java}
> /**
> * CommandProcessingThread that process commands asynchronously.
> */
> class CommandProcessingThread extends Thread {
> private final BPServiceActor actor;
> private final BlockingQueue<Runnable> queue;
> ...
> @Override
> public void run() {
> try {
> processQueue();
> } catch (Throwable t) {
> LOG.error("{} encountered fatal exception and exit.", getName(), t);
> <=== should not exit this thread
> }
> }
> {code}
> Once a unexpected error happened, a better handing should be:
> * catch the exception, appropriately deal with the error and let
> processQueue continue to run
> or
> * exit the DN process to let admin user investigate this
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