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From "Jay Shrauner (JIRA)" <j...@apache.org>
Subject [jira] [Updated] (ZOOKEEPER-1504) Multi-thread NIOServerCnxn
Date Mon, 09 Jul 2012 16:21:35 GMT

     [ https://issues.apache.org/jira/browse/ZOOKEEPER-1504?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel

Jay Shrauner updated ZOOKEEPER-1504:

    Attachment:     (was: ZOOKEEPER-1504.patch)
> Multi-thread NIOServerCnxn
> --------------------------
>                 Key: ZOOKEEPER-1504
>                 URL: https://issues.apache.org/jira/browse/ZOOKEEPER-1504
>             Project: ZooKeeper
>          Issue Type: Improvement
>          Components: server
>    Affects Versions: 3.4.3, 3.4.4, 3.5.0
>            Reporter: Jay Shrauner
>            Assignee: Jay Shrauner
>              Labels: performance, scaling
>             Fix For: 3.5.0
> NIOServerCnxnFactory is single threaded, which doesn't scale well to large numbers of
clients. This is particularly noticeable when thousands of clients connect. I propose multi-threading
this code as follows:
> - 1   acceptor thread, for accepting new connections
> - 1-N selector threads
> - 0-M I/O worker threads
> Numbers of threads are configurable, with defaults scaling according to number of cores.
Communication with the selector threads is handled via LinkedBlockingQueues, and connections
are permanently assigned to a particular selector thread so that all potentially blocking
SelectionKey operations can be performed solely by the selector thread. An ExecutorService
is used for the worker threads.
> On a 32 core machine running Linux 2.6.38, achieved best performance with 4 selector
threads and 64 worker threads for a 70% +/- 5% improvement in throughput.
> This patch incorporates and supersedes the patches for
> https://issues.apache.org/jira/browse/ZOOKEEPER-517
> https://issues.apache.org/jira/browse/ZOOKEEPER-1444
> New classes introduced in this patch are:
>   - ExpiryQueue (from ZOOKEEPER-1444): factor out the logic from SessionTrackerImpl used
to expire sessions so that the same logic can be used to expire connections
>   - RateLogger (from ZOOKEEPER-517): rate limit error message logging, currently only
used to throttle rate of logging "out of file descriptors" errors
>   - WorkerService (also in ZOOKEEPER-1505): ExecutorService wrapper that makes worker
threads daemon threads and names then in an easily debuggable manner. Supports assignable
threads (as used by CommitProcessor) and non-assignable threads (as used here).

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