tomcat服务启动，应用程序无法访问的异常，请各位高手帮忙解决。

Question

tomcat下部署了3个应用，有2个没有问题，有一个用久了，就感觉是自动挂掉了，tomcat是启动的，就是程序访问不了，程序下面无异常记录，下面是tomcat下的日志记录：
ERROR main org.apache.catalina.startup.Catalina - Catalina.stop: 
java.net.ConnectException: Connection refused: connect
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:333)
at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:195)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:182)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:366)
at java.net.Socket.connect(Socket.java:516)
at java.net.Socket.connect(Socket.java:466)
at java.net.Socket.<init>(Socket.java:366)
at java.net.Socket.<init>(Socket.java:179)
at org.apache.catalina.startup.Catalina.stopServer(Catalina.java:395)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.apache.catalina.startup.Bootstrap.stopServer(Bootstrap.java:344)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:435)
ERROR Thread-36 org.apache.catalina.connector.Connector - Protocol handler pause failed
java.net.ConnectException: Connection refused: connect
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:333)
at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:195)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:182)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:366)
at java.net.Socket.connect(Socket.java:516)
at java.net.Socket.connect(Socket.java:466)
at java.net.Socket.<init>(Socket.java:366)
at java.net.Socket.<init>(Socket.java:208)
at org.apache.jk.common.ChannelSocket.unLockSocket(ChannelSocket.java:492)
at org.apache.jk.common.ChannelSocket.pause(ChannelSocket.java:289)
at org.apache.jk.server.JkMain.pause(JkMain.java:681)
at org.apache.jk.server.JkCoyoteHandler.pause(JkCoyoteHandler.java:163)
at org.apache.catalina.connector.Connector.pause(Connector.java:1032)
at org.apache.catalina.core.StandardService.stop(StandardService.java:489)
at org.apache.catalina.core.StandardServer.stop(StandardServer.java:734)
at org.apache.catalina.startup.Catalina.stop(Catalina.java:602)
at org.apache.catalina.startup.Catalina$CatalinaShutdownHook.run(Catalina.java:645)
ERROR main org.apache.catalina.startup.Catalina - Catalina.stop: 
java.net.ConnectException: Connection refused: connect
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:333)
at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:195)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:182)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:366)
at java.net.Socket.connect(Socket.java:516)
at java.net.Socket.connect(Socket.java:466)
at java.net.Socket.<init>(Socket.java:366)
at java.net.Socket.<init>(Socket.java:179)
at org.apache.catalina.startup.Catalina.stopServer(Catalina.java:395)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.apache.catalina.startup.Bootstrap.stopServer(Bootstrap.java:344)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:435)

Answer 1

ERROR Thread-36 org.apache.catalina.connector.Connector - Protocol handler pause failed
java.net.ConnectException: Connection refused: connect
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:333)
at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:195)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:182)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:366)
at java.net.Socket.connect(Socket.java:516)
at java.net.Socket.connect(Socket.java:466)
at java.net.Socket.<init>(Socket.java:366)
at java.net.Socket.<init>(Socket.java:208)
at org.apache.jk.common.ChannelSocket.unLockSocket(ChannelSocket.java:492)
at org.apache.jk.common.ChannelSocket.pause(ChannelSocket.java:289)
at org.apache.jk.server.JkMain.pause(JkMain.java:681)
at org.apache.jk.server.JkCoyoteHandler.pause(JkCoyoteHandler.java:163)
at org.apache.catalina.connector.Connector.pause(Connector.java:1032)
at org.apache.catalina.core.StandardService.stop(StandardService.java:489)
at org.apache.catalina.core.StandardServer.stop(StandardServer.java:734)
at org.apache.catalina.startup.Catalina.stop(Catalina.java:602)
at org.apache.catalina.startup.Catalina$CatalinaShutdownHook.run(Catalina.java:645)
ERROR http-80-Processor43 org.apache.tomcat.util.threads.ThreadPool - Caught exception (java.lang.OutOfMemoryError: PermGen space) executing org.apache.tomcat.util.net.LeaderFollowerWorkerThread@102b0cf, terminating thread
ERROR main org.apache.catalina.startup.Catalina - Catalina.stop: 
java.net.ConnectException: Connection refused: connect
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:333)
at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:195)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:182)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:366)
at java.net.Socket.connect(Socket.java:516)
at java.net.Socket.connect(Socket.java:466)
at java.net.Socket.<init>(Socket.java:366)
at java.net.Socket.<init>(Socket.java:179)
at org.apache.catalina.startup.Catalina.stopServer(Catalina.java:395)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.apache.catalina.startup.Bootstrap.stopServer(Bootstrap.java:344)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:435)

Answer 2

ERROR ContainerBackgroundProcessor[StandardEngine[Catalina]] org.apache.catalina.core.StandardContext - Error reading tld listeners java.lang.NullPointerException
java.lang.NullPointerException
at org.apache.log4j.Category.isEnabledFor(Category.java:746)
at org.apache.commons.logging.impl.Log4JLogger.isTraceEnabled(Log4JLogger.java:327)
at org.apache.catalina.startup.TldConfig.tldScanResourcePaths(TldConfig.java:581)
at org.apache.catalina.startup.TldConfig.execute(TldConfig.java:282)
at org.apache.catalina.core.StandardContext.processTlds(StandardContext.java:4307)
at org.apache.catalina.core.StandardContext.start(StandardContext.java:4144)
at org.apache.catalina.core.StandardContext.reload(StandardContext.java:3025)
at org.apache.catalina.loader.WebappLoader.backgroundProcess(WebappLoader.java:432)
at org.apache.catalina.core.ContainerBase.backgroundProcess(ContainerBase.java:1278)
at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1570)
at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1579)
at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.processChildren(ContainerBase.java:1579)
at org.apache.catalina.core.ContainerBase$ContainerBackgroundProcessor.run(ContainerBase.java:1559)
at java.lang.Thread.run(Thread.java:595)
ERROR ContainerBackgroundProcessor[StandardEngine[Catalina]] org.apache.catalina.core.StandardContext - Error listenerStart
ERROR ContainerBackgroundProcessor[StandardEngine[Catalina]] org.apache.catalina.core.StandardContext - Context [/back] startup failed due to previous errors
ERROR http-80-Processor14 org.apache.catalina.connector.CoyoteAdapter - An exception or error occurred in the container during the request processing
java.lang.OutOfMemoryError: PermGen space
ERROR http-80-Processor46 org.apache.catalina.connector.CoyoteAdapter - An exception or error occurred in the container during the request processing
java.lang.OutOfMemoryError: PermGen space
ERROR http-80-Processor48 org.apache.catalina.connector.CoyoteAdapter - An exception or error occurred in the container during the request processing
java.lang.OutOfMemoryError: PermGen space
ERROR http-80-Processor14 org.apache.catalina.connector.CoyoteAdapter - An exception or error occurred in the container during the request processing
java.lang.OutOfMemoryError: PermGen space
ERROR http-80-Processor5 org.apache.catalina.connector.CoyoteAdapter - An exception or error occurred in the container during the request processing
java.lang.OutOfMemoryError: PermGen space
ERROR Thread-44 org.apache.catalina.connector.Connector - Protocol handler pause failed
java.net.ConnectException: Connection refused: connect
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:333)
at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:195)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:182)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:366)
at java.net.Socket.connect(Socket.java:516)
at java.net.Socket.connect(Socket.java:466)
at java.net.Socket.<init>(Socket.java:366)
at java.net.Socket.<init>(Socket.java:208)
at org.apache.jk.common.ChannelSocket.unLockSocket(ChannelSocket.java:492)
at org.apache.jk.common.ChannelSocket.pause(ChannelSocket.java:289)
at org.apache.jk.server.JkMain.pause(JkMain.java:681)
at org.apache.jk.server.JkCoyoteHandler.pause(JkCoyoteHandler.java:163)
at org.apache.catalina.connector.Connector.pause(Connector.java:1032)
at org.apache.catalina.core.StandardService.stop(StandardService.java:489)
at org.apache.catalina.core.StandardServer.stop(StandardServer.java:734)
at org.apache.catalina.startup.Catalina.stop(Catalina.java:602)
at org.apache.catalina.startup.Catalina$CatalinaShutdownHook.run(Catalina.java:645)
ERROR main org.apache.catalina.startup.Catalina - Catalina.stop: 
java.net.ConnectException: Connection refused: connect
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:333)
at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:195)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:182)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:366)
at java.net.Socket.connect(Socket.java:516)
at java.net.Socket.connect(Socket.java:466)
at java.net.Socket.<init>(Socket.java:366)
at java.net.Socket.<init>(Socket.java:179)
at org.apache.catalina.startup.Catalina.stopServer(Catalina.java:395)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.apache.catalina.startup.Bootstrap.stopServer(Bootstrap.java:344)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:435)
ERROR Thread-44 org.apache.catalina.connector.Connector - Protocol handler pause failed
java.net.ConnectException: Connection refused: connect
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:333)
at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:195)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:182)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:366)
at java.net.Socket.connect(Socket.java:516)
at java.net.Socket.connect(Socket.java:466)
at java.net.Socket.<init>(Socket.java:366)
at java.net.Socket.<init>(Socket.java:208)
at org.apache.jk.common.ChannelSocket.unLockSocket(ChannelSocket.java:492)
at org.apache.jk.common.ChannelSocket.pause(ChannelSocket.java:289)
at org.apache.jk.server.JkMain.pause(JkMain.java:681)
at org.apache.jk.server.JkCoyoteHandler.pause(JkCoyoteHandler.java:163)
at org.apache.catalina.connector.Connector.pause(Connector.java:1032)
at org.apache.catalina.core.StandardService.stop(StandardService.java:489)
at org.apache.catalina.core.StandardServer.stop(StandardServer.java:734)
at org.apache.catalina.startup.Catalina.stop(Catalina.java:602)
at org.apache.catalina.startup.Catalina$CatalinaShutdownHook.run(Catalina.java:645)
ERROR main org.apache.catalina.startup.Catalina - Catalina.stop: 
java.net.ConnectException: Connection refused: connect
at java.net.PlainSocketImpl.socketConnect(Native Method)
at java.net.PlainSocketImpl.doConnect(PlainSocketImpl.java:333)
at java.net.PlainSocketImpl.connectToAddress(PlainSocketImpl.java:195)
at java.net.PlainSocketImpl.connect(PlainSocketImpl.java:182)
at java.net.SocksSocketImpl.connect(SocksSocketImpl.java:366)
at java.net.Socket.connect(Socket.java:516)
at java.net.Socket.connect(Socket.java:466)
at java.net.Socket.<init>(Socket.java:366)
at java.net.Socket.<init>(Socket.java:179)
at org.apache.catalina.startup.Catalina.stopServer(Catalina.java:395)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at org.apache.catalina.startup.Bootstrap.stopServer(Bootstrap.java:344)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:435)

Answer 3

重起tomcat就可以正常使用了，我看了大概意思是：内存溢出，但我不知道该从哪里下手。
程序是用SSH框架，添加了DWR
数据库是：Oacle