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Date: Tue, 5 Feb 2013 17:58:11 +0000 (UTC)
From: "Sriram Subramanian (JIRA)" <jira@apache.org>
To: dev@kafka.apache.org
Message-ID: <JIRA.12630779.1360019643616.247617.1360087091008@arcas>
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Subject: [jira] [Commented] (KAFKA-749) Bug in socket server shutdown logic
 makes the broker hang on shutdown until it has to be killed
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    [ https://issues.apache.org/jira/browse/KAFKA-749?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13571511#comment-13571511 ] 

Sriram Subramanian commented on KAFKA-749:
------------------------------------------

If that works fine. But it looks like there really is a solution that does not need any constraints. 

1. SocketServer on shutdown closes the acceptor and processor threads. It can then add a alldone request to the queue.
2. Each requesthandler thread just dequeues from the request queue. If it is alldone, it just re-enqueues it and exits.
3. requesthandler shutdown just waits for all threads to exit (this is same as today).

Will this not work? 
                
> 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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