dubbo通过配置threadpool来配置线程池的类型：
fixed 固定大小线程池，启动时建立线程，不关闭，一直持有(缺省)
cached 缓存线程池，空闲一分钟自动删除，需要时重建
limited 可伸缩线程池，但池中的线程数只会增长不会收缩(为避免收缩时突然来了大流量引起的性能问题)
默认是固定大小线程池，如果服务消费者太多时会出现等待，甚至超时：
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Caused by: com.alibaba.dubbo.remoting.TimeoutException: Waiting server-side response timeout by scan timer. start
time
: 2016-04-22 10:36:58.471, end
time
: 2016-04-22 10:37:18.535, client elapsed: 342 ms, server elapsed: 19722 ms, timeout: 20000 ms, request: Request [
id
=178, version=2.0.0, twoway=
true
, event=
false
, broken=
false
, data=RpcInvocation [methodName=
install
, parameterTypes=[class com.acgist.Demo, class java.lang.String], arguments=[com.acgist.Demo@7fe5c339, ], attachments={path=com.acgist.IDemo, interface=com.acgist.IDemo, timeout=20000, version=0.0.0}]], channel:
/169
.254.183.37:60024 ->
/169
.254.183.37:20882
at com.alibaba.dubbo.remoting.exchange.support.DefaultFuture.returnFromResponse(DefaultFuture.java:188)
at com.alibaba.dubbo.remoting.exchange.support.DefaultFuture.get(DefaultFuture.java:110)
at com.alibaba.dubbo.remoting.exchange.support.DefaultFuture.get(DefaultFuture.java:84)
at com.alibaba.dubbo.rpc.protocol.dubbo.DubboInvoker.doInvoke(DubboInvoker.java:96)
at com.alibaba.dubbo.rpc.protocol.AbstractInvoker.invoke(AbstractInvoker.java:144)
at com.alibaba.dubbo.rpc.listener.ListenerInvokerWrapper.invoke(ListenerInvokerWrapper.java:74)
at com.alibaba.dubbo.monitor.support.MonitorFilter.invoke(MonitorFilter.java:75)
at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:91)
at com.alibaba.dubbo.rpc.protocol.dubbo.filter.FutureFilter.invoke(FutureFilter.java:53)
at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:91)
at com.alibaba.dubbo.rpc.filter.ConsumerContextFilter.invoke(ConsumerContextFilter.java:48)
at com.alibaba.dubbo.rpc.protocol.ProtocolFilterWrapper$1.invoke(ProtocolFilterWrapper.java:91)
at com.alibaba.dubbo.rpc.protocol.InvokerWrapper.invoke(InvokerWrapper.java:53)
at com.alibaba.dubbo.rpc.cluster.support.FailoverClusterInvoker.doInvoke(FailoverClusterInvoker.java:77)
... 5
more
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服务端提示繁忙：
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com.alibaba.dubbo.remoting.ExecutionException: class com.alibaba.dubbo.remoting.transport.dispatcher.all.AllChannelHandler error when process caught event .
at com.alibaba.dubbo.remoting.transport.dispatcher.all.AllChannelHandler.caught(AllChannelHandler.java:67)
at com.alibaba.dubbo.remoting.transport.AbstractChannelHandlerDelegate.caught(AbstractChannelHandlerDelegate.java:44)
at com.alibaba.dubbo.remoting.transport.AbstractChannelHandlerDelegate.caught(AbstractChannelHandlerDelegate.java:44)
at com.alibaba.dubbo.remoting.transport.AbstractPeer.caught(AbstractPeer.java:127)
at com.alibaba.dubbo.remoting.transport.netty.NettyHandler.exceptionCaught(NettyHandler.java:112)
at com.alibaba.dubbo.remoting.transport.netty.NettyCodecAdapter$InternalDecoder.exceptionCaught(NettyCodecAdapter.java:165)
at org.jboss.netty.channel.Channels.fireExceptionCaught(Channels.java:432)
at org.jboss.netty.channel.AbstractChannelSink.exceptionCaught(AbstractChannelSink.java:52)
at org.jboss.netty.channel.Channels.fireMessageReceived(Channels.java:302)
at com.alibaba.dubbo.remoting.transport.netty.NettyCodecAdapter$InternalDecoder.messageReceived(NettyCodecAdapter.java:148)
at org.jboss.netty.channel.Channels.fireMessageReceived(Channels.java:274)
at org.jboss.netty.channel.Channels.fireMessageReceived(Channels.java:261)
at org.jboss.netty.channel.socket.nio.NioWorker.
read
(NioWorker.java:349)
at org.jboss.netty.channel.socket.nio.NioWorker.processSelectedKeys(NioWorker.java:280)
at org.jboss.netty.channel.socket.nio.NioWorker.run(NioWorker.java:200)
at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:895)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:918)
at java.lang.Thread.run(Thread.java:662)
Caused by: java.util.concurrent.RejectedExecutionException: Thread pool is EXHAUSTED! Thread Name: DubboServerHandler-169.254.183.37:20882, Pool Size: 200 (active: 200, core: 200, max: 200, largest: 200), Task: 1108 (completed: 908), Executor status:(isShutdown:
false
, isTerminated:
false
, isTerminating:
false
),
in
dubbo:
//169
.254.183.37:20882!
at com.alibaba.dubbo.common.threadpool.support.AbortPolicyWithReport.rejectedExecution(AbortPolicyWithReport.java:53)
at java.util.concurrent.ThreadPoolExecutor.reject(ThreadPoolExecutor.java:768)
at java.util.concurrent.ThreadPoolExecutor.execute(ThreadPoolExecutor.java:656)
at com.alibaba.dubbo.remoting.transport.dispatcher.all.AllChannelHandler.caught(AllChannelHandler.java:65)
... 17
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这时可以两种选择，增加线程的数量或者修改线程池为缓存线程池。不过我推荐第二种。
http://www.acgist.com/article/348.html