[ZOOKEEPER-3579] handle NPE gracefully when the watch parameter of zookeeper java client is null

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 3.7.0
• Component/s: java client
• Labels: pull-request-available
• Assignee: Zili Chen
• Reporter: Ling Mao
• Created: 14/Oct/19 10:47
• Updated: 28/Mar/21 08:54
• Resolved: 16/Apr/20 10:52

Description

When we use the native java client

try {
  zk = new ZooKeeper(connectString, (int) sessionTimeout, null);
} catch (IOException e) {
  throw new DBException("Creating connection failed.");
}

We will get the following, this issue had existed in all the zookeeper releases for a long time

2019-10-14 18:41:49 ERROR ClientCnxn:537 - Error while calling watcher2019-10-14 18:41:49 ERROR ClientCnxn:537 - Error while calling watcherjava.lang.NullPointerException at org.apache.zookeeper.ClientCnxn$EventThread.processEvent(ClientCnxn.java:535) at org.apache.zookeeper.ClientCnxn$EventThread.run(ClientCnxn.java:510)2019-10-14 18:41:50 ERROR ClientCnxn:537 - Error while calling watcherjava.lang.NullPointerException at org.apache.zookeeper.ClientCnxn$EventThread.processEvent(ClientCnxn.java:535) at org.apache.zookeeper.ClientCnxn$EventThread.run(ClientCnxn.java:510)

Issue Links

• links to: GitHub Pull Request #1119
• links to: GitHub Pull Request #1120