b4dcd18427
Motivation:
A race detector discovered a data race in GlobalEventExecutor present in
netty 4.1.51.Final:
```
Write of size 4 at 0x0000cea08774 by thread T103:
#0 io.netty.util.internal.DefaultPriorityQueue.poll()Lio/netty/util/internal/PriorityQueueNode; DefaultPriorityQueue.java:113
#1 io.netty.util.internal.DefaultPriorityQueue.poll()Ljava/lang/Object; DefaultPriorityQueue.java:31
#2 java.util.AbstractQueue.remove()Ljava/lang/Object; AbstractQueue.java:113
#3 io.netty.util.concurrent.AbstractScheduledEventExecutor.pollScheduledTask(J)Ljava/lang/Runnable; AbstractScheduledEventExecutor.java:133
#4 io.netty.util.concurrent.GlobalEventExecutor.fetchFromScheduledTaskQueue()V GlobalEventExecutor.java:119
#5 io.netty.util.concurrent.GlobalEventExecutor.takeTask()Ljava/lang/Runnable; GlobalEventExecutor.java:106
#6 io.netty.util.concurrent.GlobalEventExecutor$TaskRunner.run()V GlobalEventExecutor.java:240
#7 io.netty.util.internal.ThreadExecutorMap$2.run()V ThreadExecutorMap.java:74
#8 io.netty.util.concurrent.FastThreadLocalRunnable.run()V FastThreadLocalRunnable.java:30
#9 java.lang.Thread.run()V Thread.java:835
#10 (Generated Stub) <null>
Previous read of size 4 at 0x0000cea08774 by thread T110:
#0 io.netty.util.internal.DefaultPriorityQueue.size()I DefaultPriorityQueue.java:46
#1 io.netty.util.concurrent.GlobalEventExecutor$TaskRunner.run()V GlobalEventExecutor.java:263
#2 io.netty.util.internal.ThreadExecutorMap$2.run()V ThreadExecutorMap.java:74
#3 io.netty.util.concurrent.FastThreadLocalRunnable.run()V FastThreadLocalRunnable.java:30
#4 java.lang.Thread.run()V Thread.java:835
#5 (Generated Stub) <null>
```
The race is legit, but benign. To trigger it requires a TaskRunner to
begin exiting and set 'started' to false, more work to be scheduled
which starts a new TaskRunner, that work then needs to schedule
additional work which modifies 'scheduledTaskQueue', and then the
original TaskRunner checks 'scheduledTaskQueue'. But there is no danger
to this race as it can only produce a false negative in the condition
which causes the code to CAS 'started' which is thread-safe.
Modifications:
Delete problematic references to scheduledTaskQueue. The only way
scheduledTaskQueue could be modified since the last check is if another
TaskRunner is running, in which case the current TaskRunner doesn't
care.
Result:
Data-race free code, and a bit less code to boot.
|
||
|---|---|---|
| .github | ||
| .mvn | ||
| all | ||
| bom | ||
| buffer | ||
| codec | ||
| codec-dns | ||
| codec-haproxy | ||
| codec-http | ||
| codec-http2 | ||
| codec-memcache | ||
| codec-mqtt | ||
| codec-redis | ||
| codec-smtp | ||
| codec-socks | ||
| codec-stomp | ||
| codec-xml | ||
| common | ||
| dev-tools | ||
| docker | ||
| example | ||
| handler | ||
| handler-proxy | ||
| license | ||
| microbench | ||
| resolver | ||
| resolver-dns | ||
| resolver-dns-native-macos | ||
| tarball | ||
| testsuite | ||
| testsuite-autobahn | ||
| testsuite-http2 | ||
| testsuite-native-image | ||
| testsuite-native-image-client | ||
| testsuite-native-image-client-runtime-init | ||
| testsuite-osgi | ||
| testsuite-shading | ||
| transport | ||
| transport-blockhound-tests | ||
| transport-native-epoll | ||
| transport-native-kqueue | ||
| transport-native-unix-common | ||
| transport-native-unix-common-tests | ||
| transport-sctp | ||
| transport-udt/lib/bin/lib/x86_64-MacOSX-gpp/jni | ||
| .fbprefs | ||
| .gitattributes | ||
| .gitignore | ||
| .lgtm.yml | ||
| CONTRIBUTING.md | ||
| LICENSE.txt | ||
| mvnw | ||
| mvnw.cmd | ||
| nohttp-checkstyle-suppressions.xml | ||
| nohttp-checkstyle.xml | ||
| NOTICE.txt | ||
| pom.xml | ||
| README.md | ||
| run-example.sh | ||
| SECURITY.md | ||
Netty Project
Netty is an asynchronous event-driven network application framework for rapid development of maintainable high performance protocol servers & clients.
Links
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:
- Latest stable Oracle JDK 7
- Latest stable Apache Maven
- If you are on Linux, you need additional development packages installed on your system, because you'll build the native transport.
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.allio.netty.bufferio.netty.codecio.netty.codec.dnsio.netty.codec.haproxyio.netty.codec.httpio.netty.codec.http2io.netty.codec.memcacheio.netty.codec.mqttio.netty.codec.redisio.netty.codec.smtpio.netty.codec.socksio.netty.codec.stompio.netty.codec.xmlio.netty.commonio.netty.handlerio.netty.handler.proxyio.netty.resolverio.netty.resolver.dnsio.netty.transportio.netty.transport.epoll(nativeomitted - reserved keyword in Java)io.netty.transport.kqueue(nativeomitted - reserved keyword in Java)io.netty.transport.unix.common(nativeomitted - reserved keyword in Java)io.netty.transport.rxtxio.netty.transport.sctpio.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.