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https://issues.apache.org/jira/browse/ZOOKEEPER-1875?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17518799#comment-17518799
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Mohammad Arshad edited comment on ZOOKEEPER-1875 at 4/7/22 11:15 AM:
---------------------------------------------------------------------
I think as proposed in the first patch we should skip the watcher processing if
either watcher or pair.event is null, but we should also add warning so in
future we can get better understanding of the use case from where problem is
coming.
{code:java}
if (watcher != null && pair.event != null) {
watcher.process(pair.event);
} else {
LOG.warn(
"Skipping watcher processing as watcher and pair.event cannot"
+ " be null. watcher={}, pair.event={}",
watcher == null ? "null" : watcher.getClass().getName(),
pair.event == null ? "null" : pair.event);
}
{code}
was (Author: arshad.mohammad):
I think as proposed in the first patch we should skip the watcher processing if
either watcher or pair.event is null, but we should also add warning so in
future we can get better understanding of the use case from where problem is
coming.
{code:java}
if (watcher != null && pair.event != null) {
watcher.process(pair.event);
} else {
LOG.warn(
"Skipping watcher processing as watcher or pair.event cannot"
+ " be null. watcher={}, pair.event={}",
watcher == null ? "null" : watcher.getClass().getName(),
pair.event == null ? "null" : pair.event);
}
{code}
> NullPointerException in ClientCnxn$EventThread.processEvent
> -----------------------------------------------------------
>
> Key: ZOOKEEPER-1875
> URL: https://issues.apache.org/jira/browse/ZOOKEEPER-1875
> Project: ZooKeeper
> Issue Type: Bug
> Components: java client
> Affects Versions: 3.4.5, 3.4.10
> Reporter: Jerry He
> Assignee: Jerry He
> Priority: Minor
> Attachments: ZOOKEEPER-1875-trunk.patch, ZOOKEEPER-1875.patch,
> ZOOKEEPER-1875.patch
>
>
> We've been seeing NullPointerException while working on HBase:
> {code}
> 14/01/30 22:15:25 INFO zookeeper.ZooKeeper: Client
> environment:user.dir=/home/biadmin/hbase-trunk
> 14/01/30 22:15:25 INFO zookeeper.ZooKeeper: Initiating client connection,
> connectString=hdtest009:2181 sessionTimeout=90000 watcher=null
> 14/01/30 22:15:25 INFO zookeeper.ClientCnxn: Opening socket connection to
> server hdtest009/9.30.194.18:2181. Will not attempt to authenticate using
> SASL (Unable to locate a login configuration)
> 14/01/30 22:15:25 INFO zookeeper.ClientCnxn: Socket connection established to
> hdtest009/9.30.194.18:2181, initiating session
> 14/01/30 22:15:25 INFO zookeeper.ClientCnxn: Session establishment complete
> on server hdtest009/9.30.194.18:2181, sessionid = 0x143986213e67e48,
> negotiated timeout = 60000
> 14/01/30 22:15:25 ERROR zookeeper.ClientCnxn: Error while calling watcher
> java.lang.NullPointerException
> at
> org.apache.zookeeper.ClientCnxn$EventThread.processEvent(ClientCnxn.java:519)
> at
> org.apache.zookeeper.ClientCnxn$EventThread.run(ClientCnxn.java:495)
> {code}
> The reason is the watcher is null in this part of the code:
> {code}
> private void processEvent(Object event) {
> try {
> if (event instanceof WatcherSetEventPair) {
> // each watcher will process the event
> WatcherSetEventPair pair = (WatcherSetEventPair) event;
> for (Watcher watcher : pair.watchers) {
> try {
> watcher.process(pair.event);
> } catch (Throwable t) {
> LOG.error("Error while calling watcher ", t);
> }
> }
> {code}
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