KAFKA-1387: Kafka getting stuck creating ephemeral node it has already created when two zookeeper sessions are established in a very short period of time

[fpj]

This is a patch to get around the problem discussed in the KAFKA-1387 jira. The tests are not passing in my box when I run them all, but they do pass when I run them individually, which indicates that there is something leaking from a test to the next. I still need to work this out and also work on further testing this. I wanted to open this PR now so that it can start getting reviewed.

[fpj]

Need to remove this commented code.

[asfbot]

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[guozhangwang]

@fpj Is this ready for review? Could you rebase?

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[fpj]

@guozhangwang you can start reviewing if you have time. I'm primarily interested in your opinion about the approach of using a zk handle directly to solve this. I think it is ok, but creates some redudancy in ZkUtils.

Things that I'm not entirely happy with about the patch:
1- Upon a connectionloss event, it'd be better to wait until a connected event before retrying. The way it is isn't wrong, but it will be looping until it reconnects.
2- The current tests cover a lot of the functionality, so I think it is not worse compared to the existing trunk code, but I want to spend a bit more time thinking about test coverage.
3- I'm thinking that we should remove ZkUtils.createEphemeralPathExpectConflictHandleZKBug.

[junrao]

It doesn't seem that we need timeout any more. We will also need to remove it from the javadoc.

[fpj]

Removed.

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[fpj]

Test failures don't seem to be related to this patch:

kafka.consumer.MetricsTest > testMetricsLeak FAILED
kafka.api.ProducerBounceTest > testBrokerFailure FAILED
kafka.producer.ProducerTest > testSendWithDeadBroker FAILED

[junrao]

space after first comma

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[junrao]

Thanks for the patch. LGTM.