Vinay created HADOOP-9275: ----------------------------- Summary: ActiveStandbyElector can join election even before Service HEALTHY, and results in null data at ActiveBreadCrumb Key: HADOOP-9275 URL: https://issues.apache.org/jira/browse/HADOOP-9275 Project: Hadoop Common Issue Type: Bug Affects Versions: 2.0.2-alpha Reporter: Vinay Assignee: Vinay
ActiveStandbyElector can store null at ActiveBreadCrumb in the below race condition. At further all failovers will fail resulting NPE. 1. ZKFC restarted. 2. due to less machine busy, first zk connection is expired even before the health monitoring returned the status. 3. On re-establishment transitionToActive will be called, at this time appData will be null, 4. So now ActiveBreadCrumb will have null. 5. After this any failovers will fail throwing {noformat}java.lang.NullPointerException at org.apache.hadoop.util.StringUtils.byteToHexString(StringUtils.java:171) at org.apache.hadoop.ha.ActiveStandbyElector.fenceOldActive(ActiveStandbyElector.java:892) at org.apache.hadoop.ha.ActiveStandbyElector.becomeActive(ActiveStandbyElector.java:797) at org.apache.hadoop.ha.ActiveStandbyElector.processResult(ActiveStandbyElector.java:475) at org.apache.zookeeper.ClientCnxn$EventThread.processEvent(ClientCnxn.java:545) at org.apache.zookeeper.ClientCnxn$EventThread.run(ClientCnxn.java:497){noformat} Should not join the election before service is HEALTHY -- This message is automatically generated by JIRA. If you think it was sent incorrectly, please contact your JIRA administrators For more information on JIRA, see: http://www.atlassian.com/software/jira