Matteo Merli 3a96e7373b Added option to do busy-wait on epoll (#8267)
Motivation:

Add an option (through a SelectStrategy return code) to have the Netty event loop thread to do busy-wait on the epoll.

The reason for this change is to avoid the context switch cost that comes when the event loop thread is blocked on the epoll_wait() call.

On average, the context switch has a penalty of ~13usec.

This benefits both:

The latency when reading from a socket
Scheduling tasks to be executed on the event loop thread.
The tradeoff, when enabling this feature, is that the event loop thread will be using 100% cpu, even when inactive.

Modification:

Added SelectStrategy option to return BUSY_WAIT
Epoll loop will do a epoll_wait() with no timeout
Use pause instruction to hint to processor that we're in a busy loop
Result:

When enabled, minimizes impact of context switch in the critical path
2018-09-28 22:52:00 +02:00
2009-03-04 10:33:09 +00:00
2018-05-15 10:39:14 +02:00
2009-08-28 07:15:49 +00:00

Netty Project

Netty is an asynchronous event-driven network application framework for rapid development of maintainable high performance protocol servers & clients.

How to build

For the detailed information about building and developing Netty, please visit the developer guide. This page only gives very basic information.

You require the following to build Netty:

Note that this is build-time requirement. JDK 5 (for 3.x) or 6 (for 4.0+) is enough to run your Netty-based application.

Branches to look

Development of all versions takes place in each branch whose name is identical to <majorVersion>.<minorVersion>. For example, the development of 3.9 and 4.0 resides in the branch '3.9' and the branch '4.0' respectively.

Usage with JDK 9

Netty can be used in modular JDK9 applications as a collection of automatic modules. The module names follow the reverse-DNS style, and are derived from subproject names rather than root packages due to historical reasons. They are listed below:

  • io.netty.all
  • io.netty.buffer
  • io.netty.codec
  • io.netty.codec.dns
  • io.netty.codec.haproxy
  • io.netty.codec.http
  • io.netty.codec.http2
  • io.netty.codec.memcache
  • io.netty.codec.mqtt
  • io.netty.codec.redis
  • io.netty.codec.smtp
  • io.netty.codec.socks
  • io.netty.codec.stomp
  • io.netty.codec.xml
  • io.netty.common
  • io.netty.handler
  • io.netty.handler.proxy
  • io.netty.resolver
  • io.netty.resolver.dns
  • io.netty.transport
  • io.netty.transport.epoll (native omitted - reserved keyword in Java)
  • io.netty.transport.kqueue (native omitted - reserved keyword in Java)
  • io.netty.transport.unix.common (native omitted - reserved keyword in Java)
  • io.netty.transport.rxtx
  • io.netty.transport.sctp
  • io.netty.transport.udt

Automatic modules do not provide any means to declare dependencies, so you need to list each used module separately in your module-info file.

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