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https://issues.apache.org/jira/browse/ZOOKEEPER-1504?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
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Jay Shrauner updated ZOOKEEPER-1504:
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Attachment: ZOOKEEPER-1504.patch
Split connection expiration out into separate thread.
> 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
>
>
> 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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