tomcat 运行错误

过mod_jk来实现apache和tomcat, tomcat 在运行一段时间后。catalina.out 日志里面包错
严重: Error registering Catalina:type=RequestProcessor,worker=jk-8009,name=JkRequest1794
javax.management.InstanceAlreadyExistsException: Catalina:type=RequestProcessor,worker=jk-8009,name=JkRequest1794
        at com.sun.jmx.mbeanserver.RepositorySupport.addMBean(RepositorySupport.java:452)
        at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.internal_addObject(DefaultMBeanServerInterceptor.java:1410)
        at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.registerObject(DefaultMBeanServerInterceptor.java:936)
        at com.sun.jmx.interceptor.DefaultMBeanServerInterceptor.registerMBean(DefaultMBeanServerInterceptor.java:337)
        at com.sun.jmx.mbeanserver.JmxMBeanServer.registerMBean(JmxMBeanServer.java:497)
        at org.apache.commons.modeler.Registry.registerComponent(Registry.java:871)
        at org.apache.jk.common.ChannelSocket.registerRequest(ChannelSocket.java:436)
        at org.apache.jk.common.HandlerRequest.decodeRequest(HandlerRequest.java:443)
        at org.apache.jk.common.HandlerRequest.invoke(HandlerRequest.java:352)
        at org.apache.jk.common.ChannelSocket.invoke(ChannelSocket.java:743)
        at org.apache.jk.common.ChannelSocket.processConnection(ChannelSocket.java:675)
        at org.apache.jk.common.SocketConnection.runIt(ChannelSocket.java:866)
        at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:683)
        at java.lang.Thread.run(Thread.java:595)
2008-4-27 0:30:26 org.apache.jk.common.ChannelSocket registerRequest
警告: Error registering request

有时候web页面会访问不了.不知道是何原因?