[gatein-issues] [JBoss JIRA] Work stopped: (GTNPORTAL-1545) Concurrency problem (HashMap used in class ConfigurationManager in multithreaded environment)

Concurrency problem (HashMap used in class ConfigurationManager in multithreaded environment) --------------------------------------------------------------------------------------------- Key: GTNPORTAL-1545 URL: https://jira.jboss.org/browse/GTNPORTAL-1545 Project: GateIn Portal Issue Type: Bug Security Level: Public(Everyone can see) Components: WebUI Affects Versions: 3.1.0-GA Environment: GateIn trunk (revision 4282) on EAP5 Reporter: Marek Posolda Assignee: Khoi Nguyen Attachments: exception-stacktrace.txt, GTNPORTAL-1545-20101025.patch Original Estimate: 6 hours Remaining Estimate: 6 hours Sometimes I can see exception during startup of performance. Exception is something like: java.lang.reflect.InvocationTargetException: ... Caused by: java.lang.Exception: Cannot find the configuration for the component org.exoplatform.portal.webui.container.UIContainerList, configId null at org.exoplatform.webui.application.WebuiApplication.createUIComponent(WebuiApplication.java:110) at org.exoplatform.webui.core.UIContainer.addChild(UIContainer.java:197) at org.exoplatform.portal.webui.portal.UIPortalComposer.<init>(UIPortalComposer.java:97) ... 71 more Whole stacktrace is attached. I am not seeing it in every test run, only sometimes. And usually the component is different in each case (sometimes it fails with different component that UIContainerList). After investigation, I founded that problem is in class org.exoplatform.webui.application.ConfigurationManager which is shared by more clients (threads) but it's using HashMap "configs_". This piece of code in ConfigurationManager.getComponentConfig(Class<?> type, String id) // Component config = configs_.get(key); if (config != null) { return config; } // process(type); // return configs_.get(key); is read component configuration (in case that this configuration is missing in map) and then it saves into HashMap and returns it. But in multithreaded environment, sometimes can still happen that this method returns null because "config_" HashMap is not thread-safe -> Exception is thrown in WebuiApplication.createUIComponent(WebuiApplication.java:110). See this article http://java.dzone.com/articles/concurrency-and-hashmap with nice simple example, which is doing very similar scenario as ConfigurationManager.