[HDFS-9052] deleteSnapshot runs into AssertionError

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Duplicate
• Assignee: Unassigned
• Reporter: Alex Ivanov
• Created: 10/Sep/15 21:20
• Updated: 16/Sep/15 18:23
• Resolved: 16/Sep/15 18:23

Description

CDH 5.0.5 upgraded from CDH 5.0.0 (Hadoop 2.3)

Upon deleting a snapshot, we run into the following assertion error. The scenario is as follows:
1. We have a program that deletes snapshots in reverse chronological order.
2. The program deletes a couple of hundred snapshots successfully but runs into the following exception:
java.lang.AssertionError: Element already exists: element=useraction.log.crypto, DELETED=[useraction.log.crypto]
3. There seems to be an issue with that snapshot, which causes a file, which normally gets overwritten in every snapshot to be added to the SnapshotDiff delete queue twice.
4. Once the deleteSnapshot is run on the problematic snapshot, if the Namenode is restarted, it cannot be started again until the transaction is removed from the EditLog.
5. Sometimes the bad snapshot can be deleted but the prior snapshot seems to "inherit" the same issue.
6. The error below is from Namenode starting when the DELETE_SNAPSHOT transaction is replayed from the EditLog.

2015-09-01 22:59:59,140 INFO [IPC Server handler 0 on 8022] BlockStateChange (BlockManager.java:logAddStoredBlock(2342)) - BLOCK* addStoredBlock: blockMap updated: 10.52.209.77:1004 is added to blk_1080833995_7093259

{blockUCState=UNDER_CONSTRUCTION, primaryNodeIndex=-1, replicas=[ReplicaUnderConstruction[[DISK]DS-16de62e5-f6e2-4ea7-aad9-f8567bded7d7:NORMAL|FINALIZED]]}

size 0
2015-09-01 22:59:59,140 INFO [IPC Server handler 0 on 8022] BlockStateChange (BlockManager.java:logAddStoredBlock(2342)) - BLOCK* addStoredBlock: blockMap updated: 10.52.209.77:1004 is added to blk_1080833996_7093260

{blockUCState=UNDER_CONSTRUCTION, primaryNodeIndex=-1, replicas=[ReplicaUnderConstruction[[DISK]DS-1def2b07-d87f-49dd-b14f-ef230342088d:NORMAL|FINALIZED]]}

size 0
2015-09-01 22:59:59,141 ERROR [IPC Server handler 0 on 8022] namenode.FSEditLogLoader (FSEditLogLoader.java:loadEditRecords(232)) - Encountered exception on operation DeleteSnapshotOp [snapshotRoot=/data/tenants/pdx-svt.baseline84/wddata, snapshotName=s2015022614_maintainer_soft_del, RpcClientId=7942c957-a7cf-44c1-880d-6eea690e1b19, RpcCallId=1]
2015-09-01 22:59:59,141 ERROR [IPC Server handler 0 on 8022] namenode.FSEditLogLoader (FSEditLogLoader.java:loadEditRecords(232)) - Encountered exception on operation DeleteSnapshotOp [snapshotRoot=/data/tenants/pdx-svt.baseline84/wddata, snapshotName=s2015022614_maintainer_soft_del, RpcClientId=7942c957-a7cf-44c1-880d-6eea690e1b19, RpcCallId=1]
java.lang.AssertionError: Element already exists: element=useraction.log.crypto, DELETED=[useraction.log.crypto]
at org.apache.hadoop.hdfs.util.Diff.insert(Diff.java:193)
at org.apache.hadoop.hdfs.util.Diff.delete(Diff.java:239)
at org.apache.hadoop.hdfs.util.Diff.combinePosterior(Diff.java:462)
at org.apache.hadoop.hdfs.server.namenode.snapshot.DirectoryWithSnapshotFeature$DirectoryDiff$2.initChildren(DirectoryWithSnapshotFeature.java:293)
at org.apache.hadoop.hdfs.server.namenode.snapshot.DirectoryWithSnapshotFeature$DirectoryDiff$2.iterator(DirectoryWithSnapshotFeature.java:303)
at org.apache.hadoop.hdfs.server.namenode.snapshot.DirectoryWithSnapshotFeature.cleanDeletedINode(DirectoryWithSnapshotFeature.java:531)
at org.apache.hadoop.hdfs.server.namenode.snapshot.DirectoryWithSnapshotFeature.cleanDirectory(DirectoryWithSnapshotFeature.java:823)
at org.apache.hadoop.hdfs.server.namenode.INodeDirectory.cleanSubtree(INodeDirectory.java:714)
at org.apache.hadoop.hdfs.server.namenode.INodeDirectory.cleanSubtreeRecursively(INodeDirectory.java:684)
at org.apache.hadoop.hdfs.server.namenode.snapshot.DirectoryWithSnapshotFeature.cleanDirectory(DirectoryWithSnapshotFeature.java:830)
at org.apache.hadoop.hdfs.server.namenode.INodeDirectory.cleanSubtree(INodeDirectory.java:714)
at org.apache.hadoop.hdfs.server.namenode.snapshot.INodeDirectorySnapshottable.removeSnapshot(INodeDirectorySnapshottable.java:341)
at org.apache.hadoop.hdfs.server.namenode.snapshot.SnapshotManager.deleteSnapshot(SnapshotManager.java:238)
at org.apache.hadoop.hdfs.server.namenode.FSEditLogLoader.applyEditLogOp(FSEditLogLoader.java:667)
at org.apache.hadoop.hdfs.server.namenode.FSEditLogLoader.loadEditRecords(FSEditLogLoader.java:224)
at org.apache.hadoop.hdfs.server.namenode.FSEditLogLoader.loadFSEdits(FSEditLogLoader.java:133)
at org.apache.hadoop.hdfs.server.namenode.FSImage.loadEdits(FSImage.java:802)
at org.apache.hadoop.hdfs.server.namenode.FSImage.loadEdits(FSImage.java:783)

Issue Links

• duplicates: HDFS-6908 incorrect snapshot directory diff generated by snapshot deletion