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ASF GitHub Bot commented on HDFS-17488: --------------------------------------- kokonguyen191 commented on code in PR #6759: URL: https://github.com/apache/hadoop/pull/6759#discussion_r1575867553 ########## hadoop-hdfs-project/hadoop-hdfs/src/main/java/org/apache/hadoop/hdfs/server/datanode/IncrementalBlockReportManager.java: ########## @@ -169,11 +169,17 @@ private synchronized StorageReceivedDeletedBlocks[] generateIBRs() { : pendingIBRs.entrySet()) { final PerStorageIBR perStorage = entry.getValue(); - // Send newly-received and deleted blockids to namenode + // Send newly-received and deleted blockids to namenode final ReceivedDeletedBlockInfo[] rdbi = perStorage.removeAll(); - if (rdbi != null) { - reports.add(new StorageReceivedDeletedBlocks(entry.getKey(), rdbi)); + if (rdbi == null) { Review Comment: I intentionally put it like this to reduce nesting and make the logic a bit easier to read > DN can fail IBRs with NPE when a volume is removed > -------------------------------------------------- > > Key: HDFS-17488 > URL: https://issues.apache.org/jira/browse/HDFS-17488 > Project: Hadoop HDFS > Issue Type: Bug > Components: hdfs > Reporter: Felix N > Assignee: Felix N > Priority: Major > Labels: pull-request-available > > > Error logs > {code:java} > 2024-04-22 15:46:33,422 [BP-1842952724-10.22.68.249-1713771988830 > heartbeating to localhost/127.0.0.1:64977] ERROR datanode.DataNode > (BPServiceActor.java:run(922)) - Exception in BPOfferService for Block pool > BP-1842952724-10.22.68.249-1713771988830 (Datanode Uuid > 1659ffaf-1a80-4a8e-a542-643f6bd97ed4) service to localhost/127.0.0.1:64977 > java.lang.NullPointerException > at > org.apache.hadoop.hdfs.protocolPB.DatanodeProtocolClientSideTranslatorPB.blockReceivedAndDeleted(DatanodeProtocolClientSideTranslatorPB.java:246) > at > org.apache.hadoop.hdfs.server.datanode.IncrementalBlockReportManager.sendIBRs(IncrementalBlockReportManager.java:218) > at > org.apache.hadoop.hdfs.server.datanode.BPServiceActor.offerService(BPServiceActor.java:749) > at > org.apache.hadoop.hdfs.server.datanode.BPServiceActor.run(BPServiceActor.java:920) > at java.lang.Thread.run(Thread.java:748) {code} > The root cause is in BPOfferService#notifyNamenodeBlock, happens when it's > called on a block belonging to a volume already removed prior. Because the > volume was already removed > > {code:java} > private void notifyNamenodeBlock(ExtendedBlock block, BlockStatus status, > String delHint, String storageUuid, boolean isOnTransientStorage) { > checkBlock(block); > final ReceivedDeletedBlockInfo info = new ReceivedDeletedBlockInfo( > block.getLocalBlock(), status, delHint); > final DatanodeStorage storage = dn.getFSDataset().getStorage(storageUuid); > > // storage == null here because it's already removed earlier. > for (BPServiceActor actor : bpServices) { > actor.getIbrManager().notifyNamenodeBlock(info, storage, > isOnTransientStorage); > } > } {code} > so IBRs with a null storage are now pending. > The reason why notifyNamenodeBlock can trigger on such blocks is up in > DirectoryScanner#reconcile > {code:java} > public void reconcile() throws IOException { > LOG.debug("reconcile start DirectoryScanning"); > scan(); > // If a volume is removed here after scan() already finished running, > // diffs is stale and checkAndUpdate will run on a removed volume > // HDFS-14476: run checkAndUpdate with batch to avoid holding the lock too > // long > int loopCount = 0; > synchronized (diffs) { > for (final Map.Entry<String, ScanInfo> entry : diffs.getEntries()) { > dataset.checkAndUpdate(entry.getKey(), entry.getValue()); > ... > } {code} > Inside checkAndUpdate, memBlockInfo is null because all the block meta in > memory is removed during the volume removal, but diskFile still exists. Then > DataNode#notifyNamenodeDeletedBlock (and further down the line, > notifyNamenodeBlock) is called on this block. > -- This message was sent by Atlassian Jira (v8.20.10#820010) --------------------------------------------------------------------- To unsubscribe, e-mail: hdfs-issues-unsubscr...@hadoop.apache.org For additional commands, e-mail: hdfs-issues-h...@hadoop.apache.org