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Nick Hill fedf3ccecb Harden ref-counting concurrency semantics (#8583)
Motivation

#8563 highlighted race conditions introduced by the prior optimistic
update optimization in 83a19d5650. These
were known at the time but considered acceptable given the perf
benefit in high contention scenarios.

This PR proposes a modified approach which provides roughly half the
gains but stronger concurrency semantics. Race conditions still exist
but their scope is narrowed to much less likely cases (releases
coinciding with retain overflow), and even in those
cases certain guarantees are still assured. Once release() returns true,
all subsequent release/retains are guaranteed to throw, and in
particular deallocate will be called at most once.

Modifications

- Use even numbers internally (including -ve) for live refcounts
- "Final" release changes to odd number (equivalent to refcount 0)
- Retain still uses faster getAndAdd, release uses CAS loop
- First CAS attempt uses non-volatile read
- Thread.yield() after a failed CAS provides a net gain

Result

More (though not completely) robust concurrency semantics for ref
counting; increased latency under high contention, but still roughly
twice as fast as the original logic. Bench results to follow
2018-11-29 08:32:32 +01:00
.github Use GitHub Issue/PR Template Feature 2016-12-07 11:40:26 -08:00
.mvn/wrapper Include mvn wrapper to make setup of development env easier 2018-01-26 08:13:17 +01:00
all [maven-release-plugin] prepare for next development iteration 2018-10-29 15:38:51 +00:00
bom [maven-release-plugin] prepare for next development iteration 2018-10-29 15:38:51 +00:00
buffer Harden ref-counting concurrency semantics (#8583) 2018-11-29 08:32:32 +01:00
codec Don't swallow intermediate write failures in MessageToMessageEncoder (#8454) 2018-11-03 10:36:26 +01:00
codec-dns [maven-release-plugin] prepare for next development iteration 2018-10-29 15:38:51 +00:00
codec-haproxy [maven-release-plugin] prepare for next development iteration 2018-10-29 15:38:51 +00:00
codec-http [maven-release-plugin] prepare for next development iteration 2018-10-29 15:38:51 +00:00
codec-http2 Defer HTTP/2 stream transition state on initial write until headers are written (#8471) 2018-11-14 08:17:43 +01:00
codec-memcache [maven-release-plugin] prepare for next development iteration 2018-10-29 15:38:51 +00:00
codec-mqtt [maven-release-plugin] prepare for next development iteration 2018-10-29 15:38:51 +00:00
codec-redis [maven-release-plugin] prepare for next development iteration 2018-10-29 15:38:51 +00:00
codec-smtp [maven-release-plugin] prepare for next development iteration 2018-10-29 15:38:51 +00:00
codec-socks [maven-release-plugin] prepare for next development iteration 2018-10-29 15:38:51 +00:00
codec-stomp [maven-release-plugin] prepare for next development iteration 2018-10-29 15:38:51 +00:00
codec-xml [maven-release-plugin] prepare for next development iteration 2018-10-29 15:38:51 +00:00
common Harden ref-counting concurrency semantics (#8583) 2018-11-29 08:32:32 +01:00
dev-tools [maven-release-plugin] prepare for next development iteration 2018-10-29 15:38:51 +00:00
docker Update to openjdk 12ea19 (#8487) 2018-11-09 16:50:58 +01:00
example Remove transitive dependency on slf4j in example (#8582) 2018-11-21 06:39:28 +01:00
handler Fix test that assumed detection of peer supported algs is not supported in BoringSSL. (#8573) 2018-11-19 12:13:05 +01:00
handler-proxy [maven-release-plugin] prepare for next development iteration 2018-10-29 15:38:51 +00:00
license Add the NOTICE of the forked portion of Apache Harmony 2018-01-30 11:22:51 +01:00
microbench Streamline CompositeByteBuf internals (#8437) 2018-11-03 10:37:07 +01:00
resolver [maven-release-plugin] prepare for next development iteration 2018-10-29 15:38:51 +00:00
resolver-dns Combine flushes in DnsNameResolver to allow usage of sendmmsg to reduce syscall costs (#8470) 2018-11-21 06:42:40 +01:00
tarball [maven-release-plugin] prepare for next development iteration 2018-10-29 15:38:51 +00:00
testsuite [maven-release-plugin] prepare for next development iteration 2018-10-29 15:38:51 +00:00
testsuite-autobahn [maven-release-plugin] prepare for next development iteration 2018-10-29 15:38:51 +00:00
testsuite-http2 [maven-release-plugin] prepare for next development iteration 2018-10-29 15:38:51 +00:00
testsuite-osgi [maven-release-plugin] prepare for next development iteration 2018-10-29 15:38:51 +00:00
testsuite-shading Include correct dependencies for testsuite-shading on windows. (#8491) 2018-11-12 20:59:44 +01:00
transport Factor out less common code-path into own method to allow inlining. (#8590) 2018-11-25 21:46:14 +01:00
transport-native-epoll Add testcase for epollWait(...) with negative timerfd values. (#8447) 2018-10-30 19:38:02 +01:00
transport-native-kqueue [maven-release-plugin] prepare for next development iteration 2018-10-29 15:38:51 +00:00
transport-native-unix-common [maven-release-plugin] prepare for next development iteration 2018-10-29 15:38:51 +00:00
transport-native-unix-common-tests [maven-release-plugin] prepare for next development iteration 2018-10-29 15:38:51 +00:00
transport-rxtx [maven-release-plugin] prepare for next development iteration 2018-10-29 15:38:51 +00:00
transport-sctp Remove @Deprecated from package-info.java file (#8591) 2018-11-23 17:03:29 +01:00
transport-udt [maven-release-plugin] prepare for next development iteration 2018-10-29 15:38:51 +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 Exclude mainframer related files from git 2018-10-14 13:20:18 +02:00
CONTRIBUTING.md Move the pull request guide to the developer guide 2014-03-12 13:13:58 +09:00
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 Add the NOTICE of the forked portion of Apache Harmony 2018-01-30 11:22:51 +01:00
pom.xml Update to netty-tcnative 2.0.20.Final (#8561) 2018-11-15 18:05:15 +01:00
README.md Provide an Automatic-Module-Name for the netty-all artifact fixes #7644 2018-01-27 20:31:16 +01:00
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.