Ming Ma created HDFS-9313: ----------------------------- Summary: Possible NullPointerException in BlockManager if no excess replica can be chosen Key: HDFS-9313 URL: https://issues.apache.org/jira/browse/HDFS-9313 Project: Hadoop HDFS Issue Type: Bug Reporter: Ming Ma
HDFS-8647 makes it easier to reason about various block placement scenarios. Here is one possible case where BlockManager won't be able to find the excess replica to delete: when storage policy changes around the same time balancer moves the block. When this happens, it will cause NullPointerException. {noformat} java.lang.NullPointerException at org.apache.hadoop.hdfs.server.blockmanagement.BlockPlacementPolicy.adjustSetsWithChosenReplica(BlockPlacementPolicy.java:156) at org.apache.hadoop.hdfs.server.blockmanagement.BlockPlacementPolicyDefault.chooseReplicasToDelete(BlockPlacementPolicyDefault.java:978) {noformat} Note that it isn't found in any production clusters. Instead, it is found from new unit tests. In addition, the issue has been there before HDFS-8647. -- This message was sent by Atlassian JIRA (v6.3.4#6332)