He Xiaoqiao created HDFS-8993: --------------------------------- Summary: Balancer throws NPE Key: HDFS-8993 URL: https://issues.apache.org/jira/browse/HDFS-8993 Project: Hadoop HDFS Issue Type: Bug Components: balancer & mover Affects Versions: 2.4.1 Reporter: He Xiaoqiao
Balancer may throw NPE because the following {{if Statements}} {code:java|firstline=705} synchronized (block) { // update locations for (String datanodeUuid : blk.getDatanodeUuids()) { final BalancerDatanode d = datanodeMap.get(datanodeUuid); if (datanode != null) { // not an unknown datanode block.addLocation(d); } } } {code} Before moving block, Balancer divides into two step to get all DNs info & some blocks of DN from NN. Regarding one DN commission after {{getDatanodeReport}} then {{getBlockList}} and one block's target is above DN just right, It will throw NPE when dispatcher. -- This message was sent by Atlassian JIRA (v6.3.4#6332)