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https://issues.apache.org/jira/browse/ZOOKEEPER-1504?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13555686#comment-13555686
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Thawan Kooburat commented on ZOOKEEPER-1504:
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For AcceptThread, you add a flag so that it will exit after select() return.
Then you can wakeup the selector using wakeupSelector() and close the selector
or, according to Java doc, selector.close() will wakeup the blocking select()
and close the selector.
> 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
>
> Attachments: ZOOKEEPER-1504.patch, ZOOKEEPER-1504.patch,
> ZOOKEEPER-1504.patch, ZOOKEEPER-1504.patch, ZOOKEEPER-1504.patch,
> ZOOKEEPER-1504.patch
>
>
> 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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