[ https://issues.apache.org/jira/browse/HDFS-3519?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]
Ming Ma updated HDFS-3519: -------------------------- Attachment: HDFS-3519-branch-2.patch Thanks, Chris. Here is the patch for branch-2. > Checkpoint upload may interfere with a concurrent saveNamespace > --------------------------------------------------------------- > > Key: HDFS-3519 > URL: https://issues.apache.org/jira/browse/HDFS-3519 > Project: Hadoop HDFS > Issue Type: Bug > Components: namenode > Reporter: Todd Lipcon > Assignee: Ming Ma > Priority: Critical > Attachments: HDFS-3519-2.patch, HDFS-3519-3.patch, > HDFS-3519-branch-2.patch, HDFS-3519.patch, test-output.txt > > > TestStandbyCheckpoints failed in [precommit build > 2620|https://builds.apache.org/job/PreCommit-HDFS-Build/2620//testReport/] > due to the following issue: > - both nodes were in Standby state, and configured to checkpoint "as fast as > possible" > - NN1 starts to save its own namespace > - NN2 starts to upload a checkpoint for the same txid. So, both threads are > writing to the same file fsimage.ckpt_12, but the actual file contents > correspond to the uploading thread's data. > - NN1 finished its saveNamespace operation while NN2 was still uploading. So, > it renamed the ckpt file. However, the contents of the file are still empty > since NN2 hasn't sent any bytes > - NN2 finishes the upload, and the rename() call fails, which causes the > directory to be marked failed, etc. > The result is that there is a file fsimage_12 which appears to be a finalized > image but in fact is incompletely transferred. When the transfer completes, > the problem "heals itself" so there wouldn't be persistent corruption unless > the machine crashes at the same time. And even then, we'd still have the > earlier checkpoint to restore from. > This same race could occur in a non-HA setup if a user puts the NN in safe > mode and issues saveNamespace operations concurrent with a 2NN checkpointing, > I believe. -- This message was sent by Atlassian JIRA (v6.3.4#6332)