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https://issues.apache.org/jira/browse/KAFKA-749?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13571425#comment-13571425
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Neha Narkhede commented on KAFKA-749:
-------------------------------------
Is this the logic for the shutdown() API in KafkaRequestHandler ? If yes, then
I don't think we can keep clearing the queue in a loop. What can happen is that
AllDone requests for the rest of the request handlers might still be in the
queue. If we clear those, then request handlers won't shutdown and some of the
request handlers will just busy wait trying to clear and offer AllDone in a
loop.
I'm thinking an easier solution might be to just require the request queue size
as large as the number of io threads. This makes sense so that io threads are
never underutilized and there is space for one request per io thread in the
request queue. Thoughts ?
> 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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