Thanks Jason! This exception is occurring mostly in pre-prod environment where we have more network blips. However, I expected that application should be back up gracefully and running. Requiring restarts is kind of bad. For now to handle this scenario, I plan to monitor the zk connection timely and kill & re-create a new one if required, but it is little ugly solution.
Having a patch/solution will be great as it would help everybody including those who have not still faced this problem. -----Original Message----- From: Jason Gustafson [mailto:ja...@confluent.io] Sent: Thursday, September 24, 2015 1:35 PM To: users@kafka.apache.org Subject: Re: ZkClient throwing NPEs Hey Hema, I'm a little surprised you're seeing this so frequently. Do you know why the zookeeper connection is so unstable? If not, then it might be worthwhile investigating a little bit to see if there are other ways to mitigate the problem. Other than that, maybe we can give the ZkClient devs a little time to investigate the issue and work on a solution. If we don't hear anything, I may be able to help with a patch since I think I have an idea how to fix the problem. -Jason On Thu, Sep 24, 2015 at 12:39 PM, Hema Bhatia <hema.bha...@apollo.edu> wrote: > Thanks Jason. > > So what is the temporary workaround for this until its fixed? For now, > we just restart the app server having this issue, but we keep seeing > this issue time and again. > > > -----Original Message----- > From: Jason Gustafson [mailto:ja...@confluent.io] > Sent: Thursday, September 24, 2015 12:21 PM > To: users@kafka.apache.org > Subject: Re: ZkClient throwing NPEs > > Hey Hema, > > I'm not too familiar with ZkClient, but I took a look at the code and > it seems like there may still be a race condition around reconnects > which could cause the NPE you're seeing. I left a comment on the > github issue on the slim chance I'm not wrong: > https://github.com/sgroschupf/zkclient/issues/25. > > -Jason > > On Thu, Sep 24, 2015 at 10:09 AM, Hema Bhatia <hema.bha...@apollo.edu> > wrote: > > > Can anyone help with the below issue... > > Thanks. > > > > -----Original Message----- > > From: Hema Bhatia [mailto:hema.bha...@apollo.edu] > > Sent: Tuesday, September 22, 2015 12:57 PM > > To: users@kafka.apache.org > > Subject: ZkClient throwing NPEs > > > > Hi, > > > > I keep getting the below exception when Kafka tries to connect to > > zookeeper and zookeeper is momentarily not able to connect. After > > that, connection does not restore unless we restart the servers. > > > > This may be connected to this issue : > > https://issues.apache.org/jira/browse/KAFKA-824 But I am already > > using zkclient-0.5, and still seeing this issue. > > > > > > java.lang.NullPointerException: null > > > > at > > org.I0Itec.zkclient.ZkConnection.exists(ZkConnection.java:107) > > ~[zkclient-0.5.jar:0.5] > > > > at > > org.I0Itec.zkclient.ZkClient$3.call(ZkClient.java:631) > > ~[zkclient-0.5.jar:0.5] > > > > at > > org.I0Itec.zkclient.ZkClient$3.call(ZkClient.java:628) > > ~[zkclient-0.5.jar:0.5] > > > > at > > org.I0Itec.zkclient.ZkClient.retryUntilConnected(ZkClient.java:883) > > ~[zkclient-0.5.jar:0.5] > > > > at > > org.I0Itec.zkclient.ZkClient.exists(ZkClient.java:628) > > ~[zkclient-0.5.jar:0.5] > > > > at > > org.I0Itec.zkclient.ZkClient.exists(ZkClient.java:637) > > ~[zkclient-0.5.jar:0.5] > > > > at > > kafka.admin.AdminUtils$.topicExists(AdminUtils.scala:163) > > ~[kafka_2.10-0.8.2.0.jar:na] > > > > at > > kafka.admin.AdminUtils.topicExists(AdminUtils.scala) > > ~[kafka_2.10-0.8.2.0.jar:na] > > > > Any ideas of how to solve this issue? > > > > Thanks, > > Hema > > > > >
