I installed tomcat 7 to upgraded my JIRA projeect version from 5.0 to 6. After I place the project folder in tomcat's webapps. I run this localhost:8080/jira after long time running, it throws some error message. Please help us to fix this problem thanks in advance

java.lang.RuntimeException: PermGen space
    at com.atlassian.event.internal.SingleParameterMethodListenerInvoker.invoke(SingleParameterMethodListenerInvoker.java:54)
    at com.atlassian.event.internal.AsynchronousAbleEventDispatcher$2.run(AsynchronousAbleEventDispatcher.java:66)
    at com.atlassian.event.internal.AsynchronousAbleEventDispatcher$1.execute(AsynchronousAbleEventDispatcher.java:32)
    at com.atlassian.event.internal.AsynchronousAbleEventDispatcher.dispatch(AsynchronousAbleEventDispatcher.java:60)
    at com.atlassian.event.internal.EventPublisherImpl.invokeListeners(EventPublisherImpl.java:160)
    at com.atlassian.event.internal.EventPublisherImpl.publish(EventPublisherImpl.java:79)
    at com.atlassian.plugin.event.impl.DefaultPluginEventManager.broadcast(DefaultPluginEventManager.java:84)
    at com.atlassian.plugin.manager.DefaultPluginManager.addPlugins(DefaultPluginManager.java:768)
    at com.atlassian.plugin.manager.DefaultPluginManager.init(DefaultPluginManager.java:200)
    at com.atlassian.jira.plugin.JiraPluginManager.start(JiraPluginManager.java:63)
    at com.atlassian.jira.ComponentManager$PluginSystem.start(ComponentManager.java:635)
    at com.atlassian.jira.ComponentManager.startJIRA(ComponentManager.java:214)
    at com.atlassian.jira.ComponentManager.quickStart(ComponentManager.java:208)
    at com.atlassian.jira.ComponentManager.start(ComponentManager.java:193)
    at com.atlassian.jira.upgrade.PluginSystemLauncher.start(PluginSystemLauncher.java:23)
    at com.atlassian.jira.startup.DefaultJiraLauncher$3.run(DefaultJiraLauncher.java:107)
    at com.atlassian.jira.config.database.DatabaseConfigurationManagerImpl.doNowOrEnqueue(DatabaseConfiguration
java tomcat tomcat7 jira jira-rest-java-api
Edit
Report