[笔记]netty随笔

记录使用过程中偶然发现的一些关键逻辑。先做记录，以后netty知识有一定体系再做整理

childGroup

服务器中有俩group，一个是parentGroup，负责处理链接请求，一个是childGroup，负责业务逻辑。

channelActive是在childGroup中触发的。

新建立链接后会触发channelActive这个事件，parent会将此事件打包成任务放到child的taskqueue中
offerTask:353, SingleThreadEventExecutor (io.netty.util.concurrent)
addTask:344, SingleThreadEventExecutor (io.netty.util.concurrent)
execute:836, SingleThreadEventExecutor (io.netty.util.concurrent)
execute0:827, SingleThreadEventExecutor (io.netty.util.concurrent)
execute:817, SingleThreadEventExecutor (io.netty.util.concurrent)
register:483, AbstractChannel$AbstractUnsafe (io.netty.channel)
register:89, SingleThreadEventLoop (io.netty.channel)
register:83, SingleThreadEventLoop (io.netty.channel)
register:86, MultithreadEventLoopGroup (io.netty.channel)
channelRead:215, ServerBootstrap$ServerBootstrapAcceptor (io.netty.bootstrap)
invokeChannelRead:444, AbstractChannelHandlerContext (io.netty.channel)
invokeChannelRead:420, AbstractChannelHandlerContext (io.netty.channel)
fireChannelRead:412, AbstractChannelHandlerContext (io.netty.channel)
channelRead:1410, DefaultChannelPipeline$HeadContext (io.netty.channel)
invokeChannelRead:440, AbstractChannelHandlerContext (io.netty.channel)
invokeChannelRead:420, AbstractChannelHandlerContext (io.netty.channel)
fireChannelRead:919, DefaultChannelPipeline (io.netty.channel)
read:97, AbstractNioMessageChannel$NioMessageUnsafe (io.netty.channel.nio)
processSelectedKey:788, NioEventLoop (io.netty.channel.nio)
processSelectedKeysOptimized:724, NioEventLoop (io.netty.channel.nio)
processSelectedKeys:650, NioEventLoop (io.netty.channel.nio)
run:562, NioEventLoop (io.netty.channel.nio)
run:997, SingleThreadEventExecutor$4 (io.netty.util.concurrent)
run:74, ThreadExecutorMap$2 (io.netty.util.internal)
run:30, FastThreadLocalRunnable (io.netty.util.concurrent)
run:842, Thread (java.lang)

child执行任务
channelActive:41, NettyHandler (com.example.demo.demos.service)
invokeChannelActive:262, AbstractChannelHandlerContext (io.netty.channel)
invokeChannelActive:238, AbstractChannelHandlerContext (io.netty.channel)
fireChannelActive:231, AbstractChannelHandlerContext (io.netty.channel)
channelActive:1398, DefaultChannelPipeline$HeadContext (io.netty.channel)
invokeChannelActive:258, AbstractChannelHandlerContext (io.netty.channel)
invokeChannelActive:238, AbstractChannelHandlerContext (io.netty.channel)
fireChannelActive:895, DefaultChannelPipeline (io.netty.channel)
register0:522, AbstractChannel$AbstractUnsafe (io.netty.channel)
access$200:429, AbstractChannel$AbstractUnsafe (io.netty.channel)
run:486, AbstractChannel$AbstractUnsafe$1 (io.netty.channel)
runTask:174, AbstractEventExecutor (io.netty.util.concurrent)
safeExecute:167, AbstractEventExecutor (io.netty.util.concurrent)
runAllTasks:470, SingleThreadEventExecutor (io.netty.util.concurrent)
run:569, NioEventLoop (io.netty.channel.nio)
run:997, SingleThreadEventExecutor$4 (io.netty.util.concurrent)
run:74, ThreadExecutorMap$2 (io.netty.util.internal)
run:30, FastThreadLocalRunnable (io.netty.util.concurrent)
run:842, Thread (java.lang)

从哪获取child？
ServerBootstrapAcceptor中会存储childGroup，通过这个childGroup以轮询这种负载均衡算法将任务设置到group中的一个loop里

ServerBootstrapAcceptor.childGroup何时何地设置？

<init>:186, ServerBootstrap$ServerBootstrapAcceptor (io.netty.bootstrap)
run:154, ServerBootstrap$1$1 (io.netty.bootstrap)
runTask:174, AbstractEventExecutor (io.netty.util.concurrent)
safeExecute:167, AbstractEventExecutor (io.netty.util.concurrent)
runAllTasks:470, SingleThreadEventExecutor (io.netty.util.concurrent)
run:569, NioEventLoop (io.netty.channel.nio)
run:997, SingleThreadEventExecutor$4 (io.netty.util.concurrent)
run:74, ThreadExecutorMap$2 (io.netty.util.internal)
run:30, FastThreadLocalRunnable (io.netty.util.concurrent)
run:842, Thread (java.lang)

child和parent为一个loop时，如何更换pipeline？
pipeline跟channel绑定，而不是与loop绑定

parent在那里将channel移交给child的selector？

bossGroup设置为1就行了？
貌似只有一个channel在处理accept请求(如果服务端只开了一个端口监听服务)，bossGroup设置多了也只会用一个loop。
这个观点还有待进一步验证