记一次生产Dubbo线程池耗尽的问题排查处理

        运维的某一系统，技术架构采用Dubbo + SSM(Spring + SpringMVC + Mybatis)开发，项目拆分成N个大模块，分布式部署在N台服务器上，注册中心采用zookeeper。该系统在交付使用一段时间后，随着用户量和请求数的不断增加，出现了系统性能的瓶颈。因此需要系统治疗师给它压脉诊断，找出病端，提升性能。系统在交付之初是初始化配置的，并没有做针对性的优化。这不，初出茅庐的Dubbo项目这就刚刚经历了它的第一次考验。

Caused by: java.util.concurrent.RejectedExecutionException: Thread pool is EXHAUSTED! 
Thread Name: DubboServerHandler-10.0.11.155:20884, Pool Size: 200 (active: 200, core: 200, max: 200, largest: 200), 
Task: 750989 (completed: 750789), Executor status:(isShutdown:false, isTerminated:false, isTerminating:false), in dubbo://10.0.11.155:20884!
 at com.alibaba.dubbo.common.threadpool.support.AbortPolicyWithReport.rejectedExecution(AbortPolicyWithReport.java:53)
 at java.util.concurrent.ThreadPoolExecutor.reject(ThreadPoolExecutor.java:821)
 at java.util.concurrent.ThreadPoolExecutor.execute(ThreadPoolExecutor.java:1372)
 at com.alibaba.dubbo.remoting.transport.dispatcher.all.AllChannelHandler.received(AllChannelHandler.