Thanks Jonathan, I didn't spot that JIRA.

Phil

-----Original Message-----
From: Jonathan Bond [mailto:jb...@netflix.com.INVALID] 
Sent: 12 April 2016 14:08
To: users@kafka.apache.org
Subject: Re: KafkaProducer 0.9.0.1 continually sends metadata requests

Phil,
In our case this bug placed significant load on our brokers. We raised a bug  
https://issues.apache.org/jira/browse/KAFKA-3358 to get this resolved.

On Tue, Apr 12, 2016 at 5:39 AM Phil Luckhurst <phil.luckhu...@encycle.com>
wrote:

> With debug logging turned on we've sometimes seen our logs filling up 
> with the kafka producer sending metadata requests every 100ms e.g.
>
> 2016-04-08 10:39:33,592 DEBUG [kafka-producer-network-thread | 
> phil-pa-1]
> org.apache.kafka.clients.NetworkClient: Sending metadata request 
> ClientRequest(expectResponse=true, callback=null, 
> request=RequestSend(header={api_key=3,api_version=0,correlation_id=249
> ,client_id=phil-pa-1}, body={topics=[phil-pa-1-device-update]}), 
> isInitiatedByNetworkClient, createdTimeMs=1460108373592, sendTimeMs=0) 
> to node 0
> 2016-04-08 10:39:33,592 DEBUG [kafka-producer-network-thread | 
> phil-pa-1]
> org.apache.kafka.clients.Metadata: Updated cluster metadata version 
> 248 to Cluster(nodes = [Node(0, ta-eng-kafka2, 9092)], partitions = 
> [Partition(topic = phil-pa-1-device-update, partition = 0, leader = 0, 
> replicas = [0,], isr = [0,]])
> 2016-04-08 10:39:33,698 DEBUG [kafka-producer-network-thread | 
> phil-pa-1]
> org.apache.kafka.clients.NetworkClient: Sending metadata request 
> ClientRequest(expectResponse=true, callback=null, 
> request=RequestSend(header={api_key=3,api_version=0,correlation_id=250
> ,client_id=phil-pa-1}, body={topics=[phil-pa-1-device-update]}), 
> isInitiatedByNetworkClient, createdTimeMs=1460108373698, sendTimeMs=0) 
> to node 0
> 2016-04-08 10:39:33,698 DEBUG [kafka-producer-network-thread | 
> phil-pa-1]
> org.apache.kafka.clients.Metadata: Updated cluster metadata version 
> 249 to Cluster(nodes = [Node(0, ta-eng-kafka2, 9092)], partitions = 
> [Partition(topic = phil-pa-1-device-update, partition = 0, leader = 0, 
> replicas = [0,], isr = [0,]])
>
> These metadata requests continue to be sent every 100ms 
> (retry.backoff.ms) until we stop the process.
>
> This only seems to happen if the KafkaProducer instance is created but 
> not used to publish a message for 5 minutes. After 5 minutes (
> metadata.max.age.ms) the producer thread sends a metadata request to 
> the server that has an empty topics list and the server responds with 
> the partition information for *all* topics hosted on the server.
>
> 2016-04-11 14:16:39,320 DEBUG [kafka-producer-network-thread | 
> phil-pa-1]
> org.apache.kafka.clients.NetworkClient: Sending metadata request 
> ClientRequest(expectResponse=true, callback=null, 
> request=RequestSend(header={api_key=3,api_version=0,correlation_id=0,c
> lient_id=phil-pa-1}, body={topics=[]}), isInitiatedByNetworkClient, 
> createdTimeMs=1460380599289,
> sendTimeMs=0) to node -1
>
> If we then use that KafkaProducer instance to send a message the next 
> 'Sending meta request' will just be for the topic we have sent the 
> message to and this then triggers the flood of retry requests as noted above.
>
> If we ensure we send the first message within the time set by 
> metadata.max.age.ms (default 5 minutes) then everything works as 
> expected and the metadata requests do not continually get retried.
>
> In many cases I can understand that creating a KafkaProducer and then 
> not using it within 5 minutes is not usual but in our case we're 
> creating it when our REST based application starts up and we can't 
> guarantee that a message will be published within that time. To get 
> around this we are currently posting a test message to the topic right 
> after creating the KafkaProducer prevents it happening.
>
> I'm not sure if this is worthy of a fix but I thought I'd post it here 
> in case someone else hits the same problem.
>
> Regards,
> Phil Luckhurst
>

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