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https://issues.apache.org/jira/browse/KAFKA-749?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13571067#comment-13571067
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Sriram Subramanian commented on KAFKA-749:
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Took a look at this.
1. This adds another layer of locking to the Request queue which in itself is a
Blocking queue implementation. This does not seem very efficient. Either we
implement our blocking queue or use the api.
2. Having said that, it seems a lot easier to just purge the queue. Is this not
an option?
3. If 2 is not possible, a more elegant way is to use the poison pill approach.
We shutdown the socket server, and enqueue a shutdown request to the queue.
Each request handler thread dequeues the request, checks it is is shutdown
request, if so re-queues it and exits.
> Bug in socket server shutdown logic makes the broker hang on shutdown until
> it has to be killed
> -----------------------------------------------------------------------------------------------
>
> Key: KAFKA-749
> URL: https://issues.apache.org/jira/browse/KAFKA-749
> Project: Kafka
> Issue Type: Bug
> Components: network
> Affects Versions: 0.8
> Reporter: Neha Narkhede
> Assignee: Neha Narkhede
> Priority: Blocker
> Labels: bugs, p1
> Attachments: kafka-749-v1.patch
>
> Original Estimate: 24h
> Remaining Estimate: 24h
>
> The current shutdown logic of the server shuts down the io threads first,
> followed by acceptor and finally processor threads. The shutdown API of io
> threads enqueues a special AllDone command into the common request queue. It
> shuts down the io thread when it dequeues this special all done command. What
> can happen is that while this shutdown command processing is happening on the
> io threads, the network/processor threads can still accept new connections
> and requests and will add those new requests to the request queue. That
> means, more requests can be enqueued after the AllDone command. What happens
> is that after the io threads have shutdown, there is no thread available to
> dequeue from the request queue. So the processor threads can hang while
> adding new requests to a full request queue, thereby blocking the server from
> shutting down.
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