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Nick Hill 166caf96ef Avoid unnecessary epoll event loop wake-ups (#9605)
Motivation

The recently-introduced event loop scheduling hooks can be exploited by
the epoll transport to avoid waking the event loop when scheduling
future tasks if there is a timer already set to wake up sooner.

There is also a "default" timeout which will wake the event
loop after 1 second if there are no pending future tasks. The
performance impact of these wakeups themselves is likely negligible but
there's significant overhead in having to re-arm the timer every time
the event loop goes to sleep (see #7816). It's not 100% clear why this
timeout was there originally but we're sure it's no longer needed.

Modification

Combine the existing volatile wakenUp and non-volatile prevDeadlineNanos
fields into a single AtomicLong that stores the next scheduled wakeup
time while the event loop is in epoll_wait, and is -1 while it is awake.

Use this as a guard to debounce wakeups from both immediate scheduled
tasks and future scheduled tasks, the latter using the new
before/afterScheduledTaskSubmitted overrides and based on whether the
new deadline occurs prior to an already-scheduled timer.

A similar optimization was already added to NioEventLoop, but it still
uses two separate volatiles. We should consider similar streamlining of
that in a future update.

Result

Fewer event loop wakeups when scheduling future tasks, greatly reduced
overhead when no future tasks are scheduled.
2019-10-12 20:16:16 +02:00
.github Change the netty.io homepage scheme(http -> https) (#9344) 2019-07-09 21:09:42 +02:00
.mvn support publishing snapshots from docker based ci (#8634) 2018-12-07 05:43:06 +01:00
all [maven-release-plugin] prepare for next development iteration 2019-09-25 06:15:31 +00:00
bom [maven-release-plugin] prepare for next development iteration 2019-09-25 06:15:31 +00:00
buffer [maven-release-plugin] prepare for next development iteration 2019-09-25 06:15:31 +00:00
codec Fixes validation of input bytes in the Base64 decoder (#9623) 2019-10-10 20:46:39 +02:00
codec-dns [maven-release-plugin] prepare for next development iteration 2019-09-25 06:15:31 +00:00
codec-haproxy Fix typos in javadocs (#9527) 2019-10-09 17:12:52 +04:00
codec-http [DOC] Add CWE-113 warning to DefaultHttpHeaders constructor (#9646) 2019-10-10 22:47:28 +04:00
codec-http2 Fix typos in javadocs (#9527) 2019-10-09 17:12:52 +04:00
codec-memcache [maven-release-plugin] prepare for next development iteration 2019-09-25 06:15:31 +00:00
codec-mqtt [maven-release-plugin] prepare for next development iteration 2019-09-25 06:15:31 +00:00
codec-redis [maven-release-plugin] prepare for next development iteration 2019-09-25 06:15:31 +00:00
codec-smtp [maven-release-plugin] prepare for next development iteration 2019-09-25 06:15:31 +00:00
codec-socks [maven-release-plugin] prepare for next development iteration 2019-09-25 06:15:31 +00:00
codec-stomp [maven-release-plugin] prepare for next development iteration 2019-09-25 06:15:31 +00:00
codec-xml [maven-release-plugin] prepare for next development iteration 2019-09-25 06:15:31 +00:00
common Fix event loop shutdown timing fragility (#9616) 2019-10-07 11:06:01 +04:00
dev-tools [maven-release-plugin] prepare for next development iteration 2019-09-25 06:15:31 +00:00
docker Use adopt@1.13.0-0 when building with Java 13 (#9641) 2019-10-09 17:10:37 +04:00
example Fix typos in javadocs (#9527) 2019-10-09 17:12:52 +04:00
handler Do not mandate direct bytes in SslHandler queue (#9656) 2019-10-12 20:12:12 +02:00
handler-proxy [maven-release-plugin] prepare for next development iteration 2019-09-25 06:15:31 +00:00
license Use Table lookup for HPACK decoder (#9307) 2019-07-02 20:09:44 +02:00
microbench Fix typos in javadocs (#9527) 2019-10-09 17:12:52 +04:00
resolver [maven-release-plugin] prepare for next development iteration 2019-09-25 06:15:31 +00:00
resolver-dns Make some inner classes static (#9624) 2019-10-07 08:14:02 +02:00
tarball [maven-release-plugin] prepare for next development iteration 2019-09-25 06:15:31 +00:00
testsuite Fix NioEventLoopTest#testChannelsRegistered flakiness (#9650) 2019-10-09 16:57:54 +04:00
testsuite-autobahn [maven-release-plugin] prepare for next development iteration 2019-09-25 06:15:31 +00:00
testsuite-http2 Fix typos in javadocs (#9527) 2019-10-09 17:12:52 +04:00
testsuite-native-image [maven-release-plugin] prepare for next development iteration 2019-09-25 06:15:31 +00:00
testsuite-osgi [maven-release-plugin] prepare for next development iteration 2019-09-25 06:15:31 +00:00
testsuite-shading [maven-release-plugin] prepare for next development iteration 2019-09-25 06:15:31 +00:00
transport Fix NioEventLoopTest#testChannelsRegistered flakiness (#9650) 2019-10-09 16:57:54 +04:00
transport-native-epoll Avoid unnecessary epoll event loop wake-ups (#9605) 2019-10-12 20:16:16 +02:00
transport-native-kqueue Fix event loop shutdown timing fragility (#9616) 2019-10-07 11:06:01 +04:00
transport-native-unix-common Enable Netty on a big endian platform 2019-09-27 12:27:37 +02:00
transport-native-unix-common-tests [maven-release-plugin] prepare for next development iteration 2019-09-25 06:15:31 +00:00
transport-rxtx [maven-release-plugin] prepare for next development iteration 2019-09-25 06:15:31 +00:00
transport-sctp [maven-release-plugin] prepare for next development iteration 2019-09-25 06:15:31 +00:00
transport-udt [maven-release-plugin] prepare for next development iteration 2019-09-25 06:15:31 +00:00
.fbprefs Updated Find Bugs configuration 2009-03-04 10:33:09 +00:00
.gitattributes Include mvn wrapper to make setup of development env easier 2018-01-26 08:13:17 +01:00
.gitignore Add vscode specific files / directory to .gitignore (#9652) 2019-10-10 09:35:08 +04:00
CONTRIBUTING.md Change the netty.io homepage scheme(http -> https) (#9344) 2019-07-09 21:09:42 +02:00
LICENSE.txt Relicensed to Apache License v2 2009-08-28 07:15:49 +00:00
mvnw Include mvn wrapper to make setup of development env easier 2018-01-26 08:13:17 +01:00
mvnw.cmd Include mvn wrapper to make setup of development env easier 2018-01-26 08:13:17 +01:00
NOTICE.txt Change the netty.io homepage scheme(http -> https) (#9344) 2019-07-09 21:09:42 +02:00
pom.xml Update commons-compress dependency (#9657) 2019-10-12 20:10:59 +02:00
README.md Change the netty.io homepage scheme(http -> https) (#9344) 2019-07-09 21:09:42 +02:00
run-example.sh Add UptimeServer and adjust UptimeClient's code style. 2017-04-28 07:41:07 +02:00

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.