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Norman Maurer ab7accb2de Don't try to put back MemoryRegionCache.Entry objects into the Recycler when recycled because of a finalizer. (#8955)
Motivation:

In MemoryRegionCache.Entry we use the Recycler to reduce GC pressure and churn. The problem is that these will also be recycled when the PoolThreadCache is collected and finalize() is called. This then can have the effect that we try to load class but the WebApp is already stoped.

This will produce an stacktrace like this on Tomcat:

```
19-Mar-2019 15:53:21.351 INFO [Finalizer] org.apache.catalina.loader.WebappClassLoaderBase.checkStateForResourceLoading Illegal access: this web application instance has been stopped already. Could not load [java.util.WeakHashMap]. The following stack trace is thrown for debugging purposes as well as to attempt to terminate the thread which caused the illegal access.
 java.lang.IllegalStateException: Illegal access: this web application instance has been stopped already. Could not load [java.util.WeakHashMap]. The following stack trace is thrown for debugging purposes as well as to attempt to terminate the thread which caused the illegal access.
	at org.apache.catalina.loader.WebappClassLoaderBase.checkStateForResourceLoading(WebappClassLoaderBase.java:1383)
	at org.apache.catalina.loader.WebappClassLoaderBase.checkStateForClassLoading(WebappClassLoaderBase.java:1371)
	at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1224)
	at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1186)
	at io.netty.util.Recycler$3.initialValue(Recycler.java:233)
	at io.netty.util.Recycler$3.initialValue(Recycler.java:230)
	at io.netty.util.concurrent.FastThreadLocal.initialize(FastThreadLocal.java:188)
	at io.netty.util.concurrent.FastThreadLocal.get(FastThreadLocal.java:142)
	at io.netty.util.Recycler$Stack.pushLater(Recycler.java:624)
	at io.netty.util.Recycler$Stack.push(Recycler.java:597)
	at io.netty.util.Recycler$DefaultHandle.recycle(Recycler.java:225)
	at io.netty.buffer.PoolThreadCache$MemoryRegionCache$Entry.recycle(PoolThreadCache.java:478)
	at io.netty.buffer.PoolThreadCache$MemoryRegionCache.freeEntry(PoolThreadCache.java:459)
	at io.netty.buffer.PoolThreadCache$MemoryRegionCache.free(PoolThreadCache.java:430)
	at io.netty.buffer.PoolThreadCache$MemoryRegionCache.free(PoolThreadCache.java:422)
	at io.netty.buffer.PoolThreadCache.free(PoolThreadCache.java:279)
	at io.netty.buffer.PoolThreadCache.free(PoolThreadCache.java:270)
	at io.netty.buffer.PoolThreadCache.free(PoolThreadCache.java:241)
	at io.netty.buffer.PoolThreadCache.finalize(PoolThreadCache.java:230)
	at java.lang.System$2.invokeFinalize(System.java:1270)
	at java.lang.ref.Finalizer.runFinalizer(Finalizer.java:102)
	at java.lang.ref.Finalizer.access$100(Finalizer.java:34)
	at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:217)
```

Beside this we also need to ensure we not try to lazy load SizeClass when the finalizer is used as it may not be present anymore if the ClassLoader is already destroyed.

This would produce an error like:

```
20-Mar-2019 11:26:35.254 INFO [Finalizer] org.apache.catalina.loader.WebappClassLoaderBase.checkStateForResourceLoading Illegal access: this web application instance has been stopped already. Could not load [io.netty.buffer.PoolArena$1]. The following stack trace is thrown for debugging purposes as well as to attempt to terminate the thread which caused the illegal access.
 java.lang.IllegalStateException: Illegal access: this web application instance has been stopped already. Could not load [io.netty.buffer.PoolArena$1]. The following stack trace is thrown for debugging purposes as well as to attempt to terminate the thread which caused the illegal access.
	at org.apache.catalina.loader.WebappClassLoaderBase.checkStateForResourceLoading(WebappClassLoaderBase.java:1383)
	at org.apache.catalina.loader.WebappClassLoaderBase.checkStateForClassLoading(WebappClassLoaderBase.java:1371)
	at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1224)
	at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1186)
	at io.netty.buffer.PoolArena.freeChunk(PoolArena.java:287)
	at io.netty.buffer.PoolThreadCache$MemoryRegionCache.freeEntry(PoolThreadCache.java:464)
	at io.netty.buffer.PoolThreadCache$MemoryRegionCache.free(PoolThreadCache.java:429)
	at io.netty.buffer.PoolThreadCache$MemoryRegionCache.free(PoolThreadCache.java:421)
	at io.netty.buffer.PoolThreadCache.free(PoolThreadCache.java:278)
	at io.netty.buffer.PoolThreadCache.free(PoolThreadCache.java:269)
	at io.netty.buffer.PoolThreadCache.free(PoolThreadCache.java:240)
	at io.netty.buffer.PoolThreadCache.finalize(PoolThreadCache.java:229)
	at java.lang.System$2.invokeFinalize(System.java:1270)
	at java.lang.ref.Finalizer.runFinalizer(Finalizer.java:102)
	at java.lang.ref.Finalizer.access$100(Finalizer.java:34)
	at java.lang.ref.Finalizer$FinalizerThread.run(Finalizer.java:217)
```

Modifications:

- Only try to put the Entry back into the Recycler if the PoolThredCache is not destroyed because of the finalizer.
- Only try to access SizeClass if not triggered by finalizer.

Result:

No IllegalStateException anymoe when a webapp is reloaded in Tomcat that uses netty and uses the PooledByteBufAllocator.
2019-03-22 12:16:53 +01:00
.github Use GitHub Issue/PR Template Feature 2016-12-07 11:40:26 -08:00
.mvn support publishing snapshots from docker based ci (#8634) 2018-12-07 06:16:39 +01:00
all Use maven plugin to prevent API/ABI breakage as part of build process (#8904) 2019-03-01 19:48:29 +01:00
bom Remove OIO transport (and transports that depend on it). (#8580) 2018-11-21 15:23:18 +01:00
buffer Don't try to put back MemoryRegionCache.Entry objects into the Recycler when recycled because of a finalizer. (#8955) 2019-03-22 12:16:53 +01:00
codec Deprecate ChannelInboundHandlerAdapter and ChannelOutboundHandlerAdapter (#8929) 2019-03-13 09:46:10 +01:00
codec-dns use checkPositive/checkPositiveOrZero (#8835) 2019-02-04 15:55:07 +01:00
codec-haproxy migrate java8: use requireNonNull (#8840) 2019-02-04 10:32:25 +01:00
codec-http Fix HttpUtil.isKeepAlive to behave correctly when Connection is a comma separated list (#8924) 2019-03-13 14:30:46 +01:00
codec-http2 Deprecate ChannelInboundHandlerAdapter and ChannelOutboundHandlerAdapter (#8929) 2019-03-13 09:46:10 +01:00
codec-memcache use checkPositive/checkPositiveOrZero (#8835) 2019-02-04 15:55:07 +01:00
codec-mqtt migrate java8: use requireNonNull (#8840) 2019-02-04 10:32:25 +01:00
codec-redis migrate java8: use requireNonNull (#8840) 2019-02-04 10:32:25 +01:00
codec-smtp migrate java8: use requireNonNull (#8840) 2019-02-04 10:32:25 +01:00
codec-socks migrate java8: use requireNonNull (#8840) 2019-02-04 10:32:25 +01:00
codec-stomp use checkPositive/checkPositiveOrZero (#8835) 2019-02-04 15:55:07 +01:00
codec-xml Update to new checkstyle plugin (#8777) 2019-01-24 16:24:19 +01:00
common Allow to automatically trim the PoolThreadCache in a timely interval (#8941) 2019-03-22 11:17:40 +01:00
dev-tools Update version number to start working on Netty 5 2018-11-20 15:49:57 +01:00
docker Add docker-sync config to step up docker-usage on macOS. (#8948) 2019-03-19 08:36:07 +01:00
example Deprecate ChannelInboundHandlerAdapter and ChannelOutboundHandlerAdapter (#8929) 2019-03-13 09:46:10 +01:00
handler Correctly produce ssl alert when certificate validation fails on the client-side when using native SSL implementation. (#8949) 2019-03-18 18:51:35 +01:00
handler-proxy Deprecate ChannelInboundHandlerAdapter and ChannelOutboundHandlerAdapter (#8929) 2019-03-13 09:46:10 +01:00
license Add the NOTICE of the forked portion of Apache Harmony 2018-01-30 11:22:51 +01:00
microbench Deprecate ChannelInboundHandlerAdapter and ChannelOutboundHandlerAdapter (#8929) 2019-03-13 09:46:10 +01:00
resolver migrate java8: use requireNonNull (#8840) 2019-02-04 10:32:25 +01:00
resolver-dns Deprecate ChannelInboundHandlerAdapter and ChannelOutboundHandlerAdapter (#8929) 2019-03-13 09:46:10 +01:00
tarball Update version number to start working on Netty 5 2018-11-20 15:49:57 +01:00
testsuite Support ALLOW_HALF_CLOSURE channel option on Unix domain socket. (#8932) 2019-03-19 11:37:54 +01:00
testsuite-autobahn Deprecate ChannelInboundHandlerAdapter and ChannelOutboundHandlerAdapter (#8929) 2019-03-13 09:46:10 +01:00
testsuite-http2 Deprecate ChannelInboundHandlerAdapter and ChannelOutboundHandlerAdapter (#8929) 2019-03-13 09:46:10 +01:00
testsuite-osgi Adjust testsuite-osgi to resolve bundles from local build (#8944) 2019-03-18 09:56:08 +01:00
testsuite-shading Use maven plugin to prevent API/ABI breakage as part of build process (#8904) 2019-03-01 19:48:29 +01:00
transport DefaultChannelHandlerContext doesn't need to extend DefaultAttributeMap (#8960) 2019-03-21 08:55:54 +01:00
transport-native-epoll Support ALLOW_HALF_CLOSURE channel option on Unix domain socket. (#8932) 2019-03-19 11:37:54 +01:00
transport-native-kqueue Support ALLOW_HALF_CLOSURE channel option on Unix domain socket. (#8932) 2019-03-19 11:37:54 +01:00
transport-native-unix-common Do not use GetPrimitiveArrayCritical(...) due multiple not-fixed bugsā€¦ (#8921) 2019-03-07 10:31:20 +01:00
transport-native-unix-common-tests Deprecate ChannelInboundHandlerAdapter and ChannelOutboundHandlerAdapter (#8929) 2019-03-13 09:46:10 +01:00
transport-sctp Deprecate ChannelInboundHandlerAdapter and ChannelOutboundHandlerAdapter (#8929) 2019-03-13 09:46:10 +01:00
.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 .gitignore for docker-sync stuff 2019-03-19 14:04:21 +01:00
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 new netty-build version to be able to correctly detect copyright header in property files. (#8967) 2019-03-22 11:11:23 +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 Drop SPDY support (#8845) 2019-02-07 09:25:31 +01:00

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.