SpagoBI Socket connection error at cockpit widget creation

I have installed SpagoBI 5.1 with java version as 1.8.0_121.
I tried to create a new cockpit and add new widget. But getting following error:

Impossible to load dataset [XXXXXX] due to the following service errors:socket creation error;

Below is stacktrace from catalina.out:

it.eng.spagobi.rest.interceptors.RestExceptionMapper.toResponseFromGenericException: Catched service error:it.eng.spagobi.utilities.exceptions.SpagoBIServiceException: An unexpected error occured while executing service
        at it.eng.spagobi.api.DataSetResource.getDataStore(DataSetResource.java:241)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)
        at org.jboss.resteasy.core.MethodInjectorImpl.invoke(MethodInjectorImpl.java:167)
        at org.jboss.resteasy.core.ResourceMethod.invokeOnTarget(ResourceMethod.java:257)
        at org.jboss.resteasy.core.ResourceMethod.invoke(ResourceMethod.java:222)
        at org.jboss.resteasy.core.ResourceMethod.invoke(ResourceMethod.java:211)
        at org.jboss.resteasy.core.SynchronousDispatcher.getResponse(SynchronousDispatcher.java:542)
        at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:524)
        at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:126)
        at org.jboss.resteasy.plugins.server.servlet.ServletContainerDispatcher.service(ServletContainerDispatcher.java:208)
        at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.service(HttpServletDispatcher.java:55)
        at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.service(HttpServletDispatcher.java:50)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
        at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
        at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
        at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953)
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
        at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1041)
        at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:603)
        at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at java.lang.Thread.run(Thread.java:745) Caused by: java.lang.RuntimeException: An unexpected error occured while executing method
        at it.eng.spagobi.tools.dataset.DatasetManagementAPI.getDataStore(DatasetManagementAPI.java:401)
        at it.eng.spagobi.api.DataSetResource.getDataStore(DataSetResource.java:224)
        ... 34 more Caused by: it.eng.spagobi.tools.dataset.cache.CacheException: An unexpected error occured while initializing cache
        at it.eng.spagobi.tools.dataset.cache.SpagoBICacheManager.initializeCache(SpagoBICacheManager.java:76)
        at it.eng.spagobi.tools.dataset.cache.SpagoBICacheManager.getCache(SpagoBICacheManager.java:59)
        at it.eng.spagobi.tools.dataset.DatasetManagementAPI.getDataStore(DatasetManagementAPI.java:377)
        ... 35 more it.eng.spagobi.rest.interceptors.RestExceptionMapper.toResponseFromGenericException: Catched service error: it.eng.spagobi.utilities.exceptions.SpagoBIServiceException: An unexpected error occured while executing service
        at it.eng.spagobi.api.DataSetResource.getDataStore(DataSetResource.java:241)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:498)
        at org.jboss.resteasy.core.MethodInjectorImpl.invoke(MethodInjectorImpl.java:167)
        at org.jboss.resteasy.core.ResourceMethod.invokeOnTarget(ResourceMethod.java:257)
        at org.jboss.resteasy.core.ResourceMethod.invoke(ResourceMethod.java:222)
        at org.jboss.resteasy.core.ResourceMethod.invoke(ResourceMethod.java:211)
        at org.jboss.resteasy.core.SynchronousDispatcher.getResponse(SynchronousDispatcher.java:542)
        at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:524)
        at org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:126)
        at org.jboss.resteasy.plugins.server.servlet.ServletContainerDispatcher.service(ServletContainerDispatcher.java:208)
        at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.service(HttpServletDispatcher.java:55)
        at org.jboss.resteasy.plugins.server.servlet.HttpServletDispatcher.service(HttpServletDispatcher.java:50)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
        at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:222)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:123)
        at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:502)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:171)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
        at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:953)
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
        at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1041)
        at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:603)
        at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:310)
        at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
        at java.lang.Thread.run(Thread.java:745) Caused by: java.lang.RuntimeException: An unexpected error occured while executing method
        at it.eng.spagobi.tools.dataset.DatasetManagementAPI.getDataStore(DatasetManagementAPI.java:401)
        at it.eng.spagobi.api.DataSetResource.getDataStore(DataSetResource.java:224)
        ... 34 more Caused by: it.eng.spagobi.tools.dataset.cache.CacheException: An unexpected error occured while initializing cache
        at it.eng.spagobi.tools.dataset.cache.SpagoBICacheManager.initializeCache(SpagoBICacheManager.java:76)
        at it.eng.spagobi.tools.dataset.cache.SpagoBICacheManager.getCache(SpagoBICacheManager.java:59)
        at it.eng.spagobi.tools.dataset.DatasetManagementAPI.getDataStore(DatasetManagementAPI.java:377)
        ... 35 more

I am running SpagoBI on Ubuntu 16.04(Linux) server. Following is output I am getting in terminal when SpagoBIStartup.sh is executed:

[Server@5451c3a8]: [Thread[main,5,main]]: checkRunning(false) entered
[Server@5451c3a8]: [Thread[main,5,main]]: checkRunning(false) exited
[Server@5451c3a8]: Startup sequence initiated from main() method
[Server@5451c3a8]: Loaded properties from [/var/www/html/[DIR_SPAGO]/database/server.properties]
[Server@5451c3a8]: Initiating startup sequence...
[Server@5451c3a8]: Server socket opened successfully in 7 ms.
[Server@5451c3a8]: [Thread[HSQLDB Server @5451c3a8,5,main]]: Database [index=0db=file:./foodmart, alias=foodmart] did not open: org.hsqldb.HsqlException: Out of Memory
[Server@5451c3a8]: [Thread[HSQLDB Server @5451c3a8,5,main]]: run()/openDatabases(): 
[Server@5451c3a8]: Initiating shutdown sequence...
[Server@5451c3a8]: Shutdown sequence completed in 1 ms.
[Server@5451c3a8]: 2017-01-27 07:33:12.852 SHUTDOWN : System.exit() is called next

Here is the screenshot: Any help is welcome !!!

It was memory issue.. Connection to Foodmart database was not getting opened.. We upgraded our server to server with bigger memory.. and this issue got resolved..