[jira] [Created] (KAFKA-4951) KafkaProducer may writes duplicated message sometimes

["cuiyang (JIRA)" <ji...@apache.org>]

cuiyang created KAFKA-4951:
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             Summary: KafkaProducer may writes duplicated message sometimes
                 Key: KAFKA-4951
                 URL: https://issues.apache.org/jira/browse/KAFKA-4951
             Project: Kafka
          Issue Type: Bug
    Affects Versions: 0.9.0.1
            Reporter: cuiyang


I foud that KafkaProducer may writes duplicated message sometimes, which is happend when:
     In Sender thread:
     NetworkClient::poll()
         -> this.selector.poll()    //write the message, such as "abc";
         -> handleTimedOutRequests(responses,updatedNow);  //Judge whether the message  "abc" which is sent above is expired or timeout,  and the judge is  based on the parameter  this.requestTimeoutMs and updatedNow;  
         -> response.request().callback().onComplete()
             -> completeBatch(batch,Errors.NETWORK_EXCEPTION,-1L,correlationId,now);   //If themessage was judged as expired, then it will be reenqueued and send repeatly next loop;
                 -> this.accumulator.reenqueue(batch,now);
The problem comes out:  If the message "abc" is sent successfully to broker, but it may be judged to expired, so the message will be sent repeately next loop, which make the message duplicated.

I can reproduce this scenario normally.
In my opinion, I think Send::handleTimedOutRequests() is not much useful, because the response of sending request from broker is succesfully and has no error. And this function  will induce to the duplicated message problems.




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