We have two servers (jboss5.2 with jbossesb4.9) running in cluster(Round Robin algorithm). Randomly we are able to see the below exception and ESB becoming unresponsive. After servers restarted everything works fine.

2014-07-31 00:27:49,720 ERROR [org.apache.juddi.v3.client.transport.wrapper.RequestHandler] Can+not+read+response+from+server.+Expected+to+read+4+bytes%2C+read+0+bytes+before+connection+was+unexpectedly+lost.
2014-07-31 00:27:50,231 ERROR [org.apache.juddi.v3.client.transport.wrapper.RequestHandler] Can+not+read+response+from+server.+Expected+to+read+4+bytes%2C+read+0+bytes+before+connection+was+unexpectedly+lost.
2014-07-31 00:27:50,742 ERROR [org.apache.juddi.v3.client.transport.wrapper.RequestHandler] Can+not+read+response+from+server.+Expected+to+read+4+bytes%2C+read+0+bytes+before+connection+was+unexpectedly+lost.
2014-07-31 00:27:51,252 ERROR [org.apache.juddi.v3.client.transport.wrapper.RequestHandler] Can+not+read+response+from+server.+Expected+to+read+4+bytes%2C+read+0+bytes+before+connection+was+unexpectedly+lost.
2014-07-31 00:27:51,763 ERROR [org.apache.juddi.v3.client.transport.wrapper.RequestHandler] Can+not+read+response+from+server.+Expected+to+read+4+bytes%2C+read+0+bytes+before+connection+was+unexpectedly+lost.
2014-07-31 00:27:52,265 ERROR [STDERR] org.jboss.soa.esb.listeners.message.MessageDeliverException: org.apache.ws.scout.transport.TransportException: java.lang.NullPointerException
2014-07-31 00:27:52,265 ERROR [STDERR] at org.jboss.soa.esb.client.ServiceInvoker.loadServiceClusterInfo(ServiceInvoker.java:545)
2014-07-31 00:27:52,265 ERROR [STDERR] at org.jboss.soa.esb.client.ServiceInvoker.<init>(ServiceInvoker.java:174)
2014-07-31 00:27:52,265 ERROR [STDERR] at org.jboss.soa.esb.client.ServiceInvoker.<init>(ServiceInvoker.java:155)
2014-07-31 00:27:52,265 ERROR [STDERR] at org.jboss.soa.esb.client.ServiceInvoker.<init>(ServiceInvoker.java:197)
2014-07-31 00:27:52,266 ERROR [STDERR] at com.hcl.sdp.esb.disti.ws.DistiProxyServiceImpl.checkStockAvailability(DistiProxyServiceImpl.java:31)
2014-07-31 00:27:52,266 ERROR [STDERR] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
2014-07-31 00:27:52,266 ERROR [STDERR] at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
2014-07-31 00:27:52,266 ERROR [STDERR] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
2014-07-31 00:27:52,266 ERROR [STDERR] at java.lang.reflect.Method.invoke(Method.java:597)
2014-07-31 00:27:52,266 ERROR [STDERR] at org.jboss.wsf.container.jboss50.invocation.AbstractInvocationHandlerJSE.invoke(AbstractInvocationHandlerJSE.java:102)
2014-07-31 00:27:52,266 ERROR [STDERR] at org.jboss.ws.core.server.ServiceEndpointInvoker.invoke(ServiceEndpointInvoker.java:241)
2014-07-31 00:27:52,266 ERROR [STDERR] at org.jboss.wsf.stack.jbws.RequestHandlerImpl.processRequest(RequestHandlerImpl.java:470)
2014-07-31 00:27:52,266 ERROR [STDERR] at org.jboss.wsf.stack.jbws.RequestHandlerImpl.handleRequest(RequestHandlerImpl.java:294)
2014-07-31 00:27:52,266 ERROR [STDERR] at org.jboss.wsf.stack.jbws.RequestHandlerImpl.doPost(RequestHandlerImpl.java:203)
2014-07-31 00:27:52,266 ERROR [STDERR] at org.jboss.wsf.stack.jbws.RequestHandlerImpl.handleHttpRequest(RequestHandlerImpl.java:129)
2014-07-31 00:27:52,266 ERROR [STDERR] at org.jboss.wsf.common.servlet.AbstractEndpointServlet.service(AbstractEndpointServlet.java:85)
2014-07-31 00:27:52,266 ERROR [STDERR] at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
2014-07-31 00:27:52,266 ERROR [STDERR] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
2014-07-31 00:27:52,266 ERROR [STDERR] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
2014-07-31 00:27:52,266 ERROR [STDERR] at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)
2014-07-31 00:27:52,266 ERROR [STDERR] at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
2014-07-31 00:27:52,266 ERROR [STDERR] at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
2014-07-31 00:27:52,266 ERROR [STDERR] at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:235)
2014-07-31 00:27:52,266 ERROR [STDERR] at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
2014-07-31 00:27:52,266 ERROR [STDERR] at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:183)
2014-07-31 00:27:52,266 ERROR [STDERR] at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:95)
2014-07-31 00:27:52,266 ERROR [STDERR] at org.jboss.web.tomcat.security.SecurityContextEstablishmentValve.process(SecurityContextEstablishmentValve.java:126)
2014-07-31 00:27:52,266 ERROR [STDERR] at org.jboss.web.tomcat.security.SecurityContextEstablishmentValve.invoke(SecurityContextEstablishmentValve.java:70)
2014-07-31 00:27:52,266 ERROR [STDERR] at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
2014-07-31 00:27:52,266 ERROR [STDERR] at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
2014-07-31 00:27:52,266 ERROR [STDERR] at org.jboss.web.tomcat.service.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:158)
2014-07-31 00:27:52,266 ERROR [STDERR] at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
2014-07-31 00:27:52,266 ERROR [STDERR] at org.jboss.web.tomcat.service.request.ActiveRequestResponseCacheValve.internalProcess(ActiveRequestResponseCacheValve.java:74)
2014-07-31 00:27:52,266 ERROR [STDERR] at org.jboss.web.tomcat.service.request.ActiveRequestResponseCacheValve.invoke(ActiveRequestResponseCacheValve.java:47)
2014-07-31 00:27:52,266 ERROR [STDERR] at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:330)
2014-07-31 00:27:52,266 ERROR [STDERR] at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:829)
2014-07-31 00:27:52,266 ERROR [STDERR] at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:599)
2014-07-31 00:27:52,266 ERROR [STDERR] at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:451)
2014-07-31 00:27:52,266 ERROR [STDERR] at java.lang.Thread.run(Thread.java:662)
2014-07-31 00:27:52,267 ERROR [STDERR] Caused by: org.jboss.soa.esb.services.registry.RegistryException: org.apache.ws.scout.transport.TransportException: java.lang.NullPointerException
2014-07-31 00:27:52,267 ERROR [STDERR] at org.jboss.internal.soa.esb.services.registry.JAXRRegistryImpl.findEPRs(JAXRRegistryImpl.java:334)
2014-07-31 00:27:52,267 ERROR [STDERR] at sun.reflect.GeneratedMethodAccessor1171.invoke(Unknown Source)
2014-07-31 00:27:52,267 ERROR [STDERR] at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
2014-07-31 00:27:52,267 ERROR [STDERR] at java.lang.reflect.Method.invoke(Method.java:597)
2014-07-31 00:27:52,267 ERROR [STDERR] at org.jboss.internal.soa.esb.services.registry.RegistryService$1.invoke(RegistryService.java:61)
2014-07-31 00:27:52,267 ERROR [STDERR] at $Proxy291.findEPRs(Unknown Source)
2014-07-31 00:27:52,267 ERROR [STDERR] at org.jboss.internal.soa.esb.services.registry.CachingRegistryInterceptor.getEPRs(CachingRegistryInterceptor.java:348)
2014-07-31 00:27:52,267 ERROR [STDERR] at org.jboss.internal.soa.esb.services.registry.CachingRegistryInterceptor.findEPRs(CachingRegistryInterceptor.java:137)
2014-07-31 00:27:52,267 ERROR [STDERR] at org.jboss.internal.soa.esb.services.registry.InVMRegistryInterceptor.findEPRs(InVMRegistryInterceptor.java:88)
2014-07-31 00:27:52,267 ERROR [STDERR] at org.jboss.soa.esb.services.registry.RegistryFactory$HeadRegistryInterceptor.findEPRs(RegistryFactory.java:229)
2014-07-31 00:27:52,267 ERROR [STDERR] at org.jboss.soa.esb.listeners.RegistryUtil.getEprs(RegistryUtil.java:226)
2014-07-31 00:27:52,267 ERROR [STDERR] at org.jboss.soa.esb.client.ServiceInvoker.loadServiceClusterInfo(ServiceInvoker.java:532)
2014-07-31 00:27:52,267 ERROR [STDERR] ... 38 more
2014-07-31 00:27:52,267 ERROR [STDERR] Caused by: javax.xml.registry.JAXRException: org.apache.ws.scout.transport.TransportException: java.lang.NullPointerException
2014-07-31 00:27:52,267 ERROR [STDERR] at org.apache.ws.scout.registry.BusinessQueryManagerV3Impl.findServices(BusinessQueryManagerV3Impl.java:663)
2014-07-31 00:27:52,267 ERROR [STDERR] at org.jboss.internal.soa.esb.services.registry.JAXRRegistryImpl.findService(JAXRRegistryImpl.java:480)
2014-07-31 00:27:52,267 ERROR [STDERR] at org.jboss.internal.soa.esb.services.registry.JAXRRegistryImpl.findEPRs(JAXRRegistryImpl.java:305)
2014-07-31 00:27:52,267 ERROR [STDERR] ... 49 more