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Kihwal Lee commented on HDFS-10763: ----------------------------------- Other tests run fine, except {{TestDataNodeVolumeFailure}}. But it also fails without all changes from this jira. > Open files can leak permanently due to inconsistent lease update > ---------------------------------------------------------------- > > Key: HDFS-10763 > URL: https://issues.apache.org/jira/browse/HDFS-10763 > Project: Hadoop HDFS > Issue Type: Bug > Affects Versions: 2.7.3, 2.6.4 > Reporter: Kihwal Lee > Assignee: Kihwal Lee > Priority: Critical > Fix For: 2.7.4, 3.0.0-alpha2 > > Attachments: HDFS-10763.br27.patch, > HDFS-10763.branch-2.7.supplement.patch, HDFS-10763.patch > > > This can heppen during {{commitBlockSynchronization()}} or a client gives up > on closing a file after retries. > From {{finalizeINodeFileUnderConstruction()}}, the lease is removed first and > then the inode is turned into the closed state. But if any block is not in > COMPLETE state, > {{INodeFile#assertAllBlocksComplete()}} will throw an exception. This will > cause the lease is removed from the lease manager, but not from the inode. > Since the lease manager does not have a lease for the file, no lease recovery > will happen for this file. Moreover, this broken state is persisted and > reconstructed through saving and loading of fsimage. Since no replication is > scheduled for the blocks for the file, this can cause a data loss and also > block decommissioning of datanode. > The lease cannot be manually recovered either. It fails with > {noformat} > ...AlreadyBeingCreatedException): Failed to RECOVER_LEASE /xyz/xyz for user1 > on > 0.0.0.1 because the file is under construction but no leases found. > at > org.apache.hadoop.hdfs.server.namenode.FSNamesystem.recoverLeaseInternal(FSNamesystem.java:2950) > ... > {noformat} > When a client retries {{close()}}, the same inconsistent state is created, > but it can work in the next time since {{checkLease()}} only looks at the > inode, not the lease manager in this case. The close behavior is different if > HDFS-8999 is activated by setting > {{dfs.namenode.file.close.num-committed-allowed}} to 1 (unlikely) or 2 > (never). > In principle, the under-construction feature of an inode and the lease in the > lease manager should never go out of sync. The fix involves two parts. > 1) Prevent inconsistent lease updates. We can achieve this by calling > {{removeLease()}} after checking the block state. > 2) Avoid reconstructing inconsistent lease states from a fsimage. 1) alone > does not correct the existing inconsistencies surviving through fsimages. > This can be done during fsimage loading time by making sure a corresponding > lease exists for each inode that are with the underconstruction feature. -- This message was sent by Atlassian JIRA (v6.3.4#6332) --------------------------------------------------------------------- To unsubscribe, e-mail: hdfs-issues-unsubscr...@hadoop.apache.org For additional commands, e-mail: hdfs-issues-h...@hadoop.apache.org