I am on Kafka 0.8.2.1 (Java 8) and have happened to run into this same
issue where the KafkaServer (broker) goes into a indefinite while loop
writing out this message:
[2015-08-04 15:45:12,350] INFO conflict in /brokers/ids/0 data:
{"jmx_port":-1,"timestamp":"1438661432074","host":"foo-bar","version":1,"port":9092}
stored data:
{"jmx_port":-1,"timestamp":"1438661429589","host":"foo-bar","version":1,"port":9092}
(kafka.utils.ZkUtils$)
[2015-08-04 15:45:12,352] INFO I wrote this conflicted ephemeral node
[{"jmx_port":-1,"timestamp":"1438661432074","host":"foo-bar","version":1,"port":9092}]
at /brokers/ids/0 a while back in a different session, hence I will
backoff for this node to be deleted by Zookeeper and retry
(kafka.utils.ZkUtils$)
These above 2 lines have been repeating continuously every few seconds
for the past 20 odd hours on this broker and this broker has been
rendered useless and is contributing to high CPU usage.
As a result the consumers have gone into a state where they no longer
consume the messages. Furthermore, this continuous looping has put Kafka
process on top of the CPU usage. I understand that bouncing the consumer
is an option and probably will "fix" this, but in our real production
environments, we won't be able to bounce the consumers. I currently have
access to logs (some of which has been pasted here). Is there any chance
these logs help in narrowing down the issue and fixing the root cause.
Can we also please add a retry max limit kind of thing in this Zookeeper
node creation logic instead of going into a indefinite while loop?
I have maintained the original timestamps in the logs so as to help
narrow down the issue. The 1438661432074 (milli second) in the log
translates to Aug 03 2015 21:10:32 (PDT) and 1438661429589 translates to
Aug 03 2015 21:10:30 (PDT). I have included that part of the log snippet
from the server.log of the broker (10.95.100.31).
[2015-08-03 21:10:29,805] ERROR Closing socket for /10.95.100.31 because
of error (kafka.network.Processor)
java.io.IOException: Broken pipe
at sun.nio.ch.FileDispatcherImpl.write0(Native Method)
at sun.nio.ch.SocketDispatcher.write(SocketDispatcher.java:47)
at sun.nio.ch.IOUtil.writeFromNativeBuffer(IOUtil.java:93)
at sun.nio.ch.IOUtil.write(IOUtil.java:65)
at sun.nio.ch.SocketChannelImpl.write(SocketChannelImpl.java:471)
at kafka.api.TopicDataSend.writeTo(FetchResponse.scala:123)
at kafka.network.MultiSend.writeTo(Transmission.scala:101)
at kafka.api.FetchResponseSend.writeTo(FetchResponse.scala:231)
at kafka.network.Processor.write(SocketServer.scala:472)
at kafka.network.Processor.run(SocketServer.scala:342)
at java.lang.Thread.run(Thread.java:745)
[2015-08-03 21:10:29,938] ERROR Closing socket for /10.95.100.31 because
of error (kafka.network.Processor)
java.io.IOException: Connection reset by peer
at sun.nio.ch.FileDispatcherImpl.read0(Native Method)
at sun.nio.ch.SocketDispatcher.read(SocketDispatcher.java:39)
at sun.nio.ch.IOUtil.readIntoNativeBuffer(IOUtil.java:223)
at sun.nio.ch.IOUtil.read(IOUtil.java:197)
at sun.nio.ch.SocketChannelImpl.read(SocketChannelImpl.java:380)
at kafka.utils.Utils$.read(Utils.scala:380)
at
kafka.network.BoundedByteBufferReceive.readFrom(BoundedByteBufferReceive.scala:54)
at kafka.network.Processor.read(SocketServer.scala:444)
at kafka.network.Processor.run(SocketServer.scala:340)
at java.lang.Thread.run(Thread.java:745)
[2015-08-03 21:10:30,045] ERROR Closing socket for /10.95.100.31 because
of error (kafka.network.Processor)
java.io.IOException: Broken pipe
at sun.nio.ch.FileDispatcherImpl.write0(Native Method)
at sun.nio.ch.SocketDispatcher.write(SocketDispatcher.java:47)
at sun.nio.ch.IOUtil.writeFromNativeBuffer(IOUtil.java:93)
at sun.nio.ch.IOUtil.write(IOUtil.java:65)
at sun.nio.ch.SocketChannelImpl.write(SocketChannelImpl.java:471)
at kafka.api.TopicDataSend.writeTo(FetchResponse.scala:123)
at kafka.network.MultiSend.writeTo(Transmission.scala:101)
at kafka.api.FetchResponseSend.writeTo(FetchResponse.scala:231)
at kafka.network.Processor.write(SocketServer.scala:472)
at kafka.network.Processor.run(SocketServer.scala:342)
at java.lang.Thread.run(Thread.java:745)
<<< a lot more similar exceptions >>>
[2015-08-03 21:10:31,304] INFO Closing socket connection to
/10.95.100.31. (kafka.network.Processor)
[2015-08-03 21:10:31,397] INFO Closing socket connection to
/10.95.100.31. (kafka.network.Processor)
[2015-08-03 21:10:31,399] INFO Closing socket connection to
/10.95.100.31. (kafka.network.Processor)
[2015-08-03 21:10:31,445] INFO Closing socket connection to
/10.95.100.31. (kafka.network.Processor)
....
<<<< bunch of similar logs as above >>>>
[2015-08-03 21:10:31,784] INFO [ReplicaFetcherManager on broker 0]
Removed fetcher for partitions [<partition list>]
(kafka.server.ReplicaFetcherManager)
[2015-08-03 21:10:31,860] INFO Closing socket connection to
/10.95.100.31. (kafka.network.Processor)
[2015-08-03 21:10:31,861] INFO 0 successfully elected as leader
(kafka.server.ZookeeperLeaderElector)
[2015-08-03 21:10:32,072] INFO Closing socket connection to
/10.95.100.31. (kafka.network.Processor)
[2015-08-03 21:10:32,074] INFO re-registering broker info in ZK for
broker 0 (kafka.server.KafkaHealthcheck)
[2015-08-03 21:10:32,103] INFO conflict in /brokers/ids/0 data:
{"jmx_port":-1,"timestamp":"1438661432074","host":"foo-bar","version":1,"port":9092}
stored data:
{"jmx_port":-1,"timestamp":"1438661429589","host":"foo-bar","version":1,"port":9092}
(kafka.utils.ZkUtils$)
[2015-08-03 21:10:32,104] INFO I wrote this conflicted ephemeral node
[{"jmx_port":-1,"timestamp":"1438661432074","host":"foo-bar","version":1,"port":9092}]
at /brokers/ids/0 a while back in a different session, hence I will
backoff for this node to be deleted by Zookeeper and retry
(kafka.utils.ZkUtils$)
[2015-08-03 21:10:38,107] INFO conflict in /brokers/ids/0 data:
{"jmx_port":-1,"timestamp":"1438661432074","host":"foo-bar","version":1,"port":9092}
stored data:
{"jmx_port":-1,"timestamp":"1438661429589","host":"foo-bar","version":1,"port":9092}
(kafka.utils.ZkUtils$)
[2015-08-03 21:10:38,109] INFO I wrote this conflicted ephemeral node
[{"jmx_port":-1,"timestamp":"1438661432074","host":"foo-bar","version":1,"port":9092}]
at /brokers/ids/0 a while back in a different session, hence I will
backoff for this node to be deleted by Zookeeper and retry
(kafka.utils.ZkUtils$)
[2015-08-03 21:10:44,118] INFO conflict in /brokers/ids/0 data:
{"jmx_port":-1,"timestamp":"1438661432074","host":"foo-bar","version":1,"port":9092}
stored data:
{"jmx_port":-1,"timestamp":"1438661429589","host":"foo-bar","version":1,"port":9092}
(kafka.utils.ZkUtils$)
[2015-08-03 21:10:44,120] INFO I wrote this conflicted ephemeral node
[{"jmx_port":-1,"timestamp":"1438661432074","host":"foo-bar","version":1,"port":9092}]
at /brokers/ids/0 a while back in a different session, hence I will
backoff for this node to be deleted by Zookeeper and retry
(kafka.utils.ZkUtils$)
[2015-08-03 21:10:50,123] INFO conflict in /brokers/ids/0 data:
{"jmx_port":-1,"timestamp":"1438661432074","host":"foo-bar","version":1,"port":9092}
stored data:
{"jmx_port":-1,"timestamp":"1438661429589","host":"foo-bar","version":1,"port":9092}
(kafka.utils.ZkUtils$)
<<< these above couple of lines continue for around 20 odd hours now >>>
I could probably get more logs if needed, assuming the VM isn't shutdown
by then.
-Jaikiran
On Monday 13 July 2015 10:34 AM, tao xiao wrote:
Finding out root cause is definitely something we should do and I hope the
new Java consumer API will not have such issues anymore. Here are my
observation of the issue: the zk retry was caused by session timeout. In
theory the ephemeral node should be removed after the session is terminated
by zk but in fact the node still presented after the session was gone. I
saw lots of slow fsync warning in zk log like below but I am not sure if
the warning has anything to do with the error I encountered.
2015-07-12 22:01:21,195 [myid:2] - WARN [SyncThread:2:FileTxnLog@334] -
fsync-ing the write ahead log in SyncThread:2 took 1023ms which will
adversely effect operation latency. See the ZooKeeper troubleshooting guide
I know in Linkedin ZK is installed on SSD does it help with this?
On Mon, 13 Jul 2015 at 12:50 Mayuresh Gharat <gharatmayures...@gmail.com>
wrote:
That would solve this. But it looks like a work around. We need to check
why this happens exactly and get to the root cause. What do you think?
Getting to the root cause of this might be really useful.
Thanks,
Mayuresh
On Sun, Jul 12, 2015 at 8:45 PM, tao xiao <xiaotao...@gmail.com> wrote:
Restart the consumers does fix the issue. But since the zk retry is
wrapped
in an infinite loop it doesn't give a chance to consumer to respond it
until some one notices and restarts. Why I suggest to have a maximum
retry
policy is if max retry is reached it can invoke a customer handler which
I
can then inject a restart call so that it can remedy itself without
people's attention.
On Mon, 13 Jul 2015 at 11:36 Jiangjie Qin <j...@linkedin.com.invalid>
wrote:
Hi Tao,
We see this error from time to time but did not think of this as a big
issue. Any reason it bothers you much?
I¹m not sure if throwing exception to user on this exception is a good
handling or not. What are user supposed to do in that case other than
retry?
Thanks,
Jiangjie (Becket) Qin
On 7/12/15, 7:16 PM, "tao xiao" <xiaotao...@gmail.com> wrote:
We saw the error again in our cluster. Anyone has the same issue
before?
On Fri, 10 Jul 2015 at 13:26 tao xiao <xiaotao...@gmail.com> wrote:
Bump the thread. Any help would be appreciated.
On Wed, 8 Jul 2015 at 20:09 tao xiao <xiaotao...@gmail.com> wrote:
Additional info
Kafka version: 0.8.2.1
zookeeper: 3.4.6
On Wed, 8 Jul 2015 at 20:07 tao xiao <xiaotao...@gmail.com> wrote:
Hi team,
I have 10 high level consumers connecting to Kafka and one of them
kept
complaining "conflicted ephemeral node" for about 8 hours. The log
was
filled with below exception
[2015-07-07 14:03:51,615] INFO conflict in
/consumers/group/ids/test-1435856975563-9a9fdc6c data:
{"version":1,"subscription":{"test.*":1},"pattern":"white_list","timest
amp":"1436275631510"}
stored data:
{"version":1,"subscription":{"test.*":1},"pattern":"white_list","timest
amp":"1436275558570"}
(kafka.utils.ZkUtils$)
[2015-07-07 14:03:51,616] INFO I wrote this conflicted ephemeral
node
[{"version":1,"subscription":{"test.*":1},"pattern":"white_list","times
tamp":"1436275631510"}]
at /consumers/group/ids/test-1435856975563-9a9fdc6c a while back
in
a
different session, hence I will backoff for this node to be
deleted
by
Zookeeper and retry (kafka.utils.ZkUtils$)
In the meantime zookeeper reported below exception for the same
time
span
2015-07-07 22:45:09,687 [myid:3] - INFO [ProcessThread(sid:3
cport:-1)::PrepRequestProcessor@645] - Got user-level
KeeperException
when processing sessionid:0x44e657ff19c0019 type:create
cxid:0x7a26
zxid:0x3015f6e77 txntype:-1 reqpath:n/a Error
Path:/consumers/group/ids/test-1435856975563-9a9fdc6c
Error:KeeperErrorCode
= NodeExists for /consumers/group/ids/test-1435856975563-9a9fdc6c
At the end zookeeper timed out the session and consumers triggered
rebalance.
I know that conflicted ephemeral node warning is to handle a
zookeeper
bug that session expiration and ephemeral node deletion are not
done
atomically but as indicated from zookeeper log the zookeeper never
got a
chance to delete the ephemeral node which made me think that the
session
was not expired at that time. And for some reason zookeeper fired
session
expire event which subsequently invoked ZKSessionExpireListener.
I
was
just wondering if anyone have ever encountered similar issue
before
and
what I can do at zookeeper side to prevent this?
Another problem is that
createEphemeralPathExpectConflictHandleZKBug
call is wrapped in a while(true) loop which runs forever until the
ephemeral node is created. Would it be better that we can employ
an
exponential retry policy with a max number of retries so that it
has a
chance to re-throw the exception back to caller and let caller
handle
it in
situation like above?
--
-Regards,
Mayuresh R. Gharat
(862) 250-7125
