NullPointerException in resetZooKeeperTrackers in HConnectionManager /
HConnectionImplementation
------------------------------------------------------------------------------------------------
Key: HBASE-5289
URL: https://issues.apache.org/jira/browse/HBASE-5289
Project: HBase
Issue Type: Bug
Components: client
Affects Versions: 0.90.5
Reporter: Krystian Nowak
This might happen on heavy load in case of lagging HBase when sharing one
HConnection by multiple threads:
{noformat}
2012-01-26 13:59:38,396 ERROR [http://*:8080-251-EventThread]
zookeeper.ClientCnxn$EventThread(532): Error while calling watcher
java.lang.NullPointerException
at
org.apache.hadoop.hbase.client.HConnectionManager$HConnectionImplementation.resetZooKeeperTrackers(HConnectionManager.java:533)
at
org.apache.hadoop.hbase.client.HConnectionManager$HConnectionImplementation.abort(HConnectionManager.java:1536)
at
org.apache.hadoop.hbase.zookeeper.ZooKeeperWatcher.connectionEvent(ZooKeeperWatcher.java:344)
at
org.apache.hadoop.hbase.zookeeper.ZooKeeperWatcher.process(ZooKeeperWatcher.java:262)
at
org.apache.zookeeper.ClientCnxn$EventThread.processEvent(ClientCnxn.java:530)
at org.apache.zookeeper.ClientCnxn$EventThread.run(ClientCnxn.java:506)
{noformat}
The following code is not protected against NPE:
{code}
private synchronized void resetZooKeeperTrackers()
throws ZooKeeperConnectionException {
LOG.info("Trying to reconnect to zookeeper");
masterAddressTracker.stop();
masterAddressTracker = null;
rootRegionTracker.stop();
rootRegionTracker = null;
clusterId = null;
this.zooKeeper = null;
setupZookeeperTrackers();
}
{code}
In some cases as proven by the log snippet above it might happen that either
masterAddressTracker or rootRegionTracker might be null.
Because of the NPE the code can't reach setupZookeeperTrackers() call.
This should be fixed at least the way as shown in one of the patches in
HBASE-5153
{code}
LOG.info("Trying to reconnect to zookeeper.");
if (this.masterAddressTracker != null) {
this.masterAddressTracker.stop();
this.masterAddressTracker = null;
}
if (this.rootRegionTracker != null) {
this.rootRegionTracker.stop();
this.rootRegionTracker = null;
}
{code}
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