Re: when testing 20 users, I get a java.util.ConcurrentModificationException error

I recently did fixed some *major* memory leaks in the
VelocityMenuDisplayer - you might try building from CVS - or using the
attached struts-menu.jar.

Matt

On 3/3/06, Kevin Drennen ([email protected])
<[email protected]> wrote:
>
> We are doing testing in our application using the struts-menu implementation
> using the velocity templates rendering an Xtree (like this example:
> http://demo.raibledesigns.com/struts-menu/velocity-xtree.jsp).
> When we test simulating 20 concurrent users on the system we enounter a
> java.util.ConcurrentModificationException error (see
> below). Any thoughts on how to fix this?
>
>
>
> 2006-03-03 09:07:51,375 - VelocimacroProxy.render() : exception VM =
> #displayMenu() : java.util.ConcurrentModificationException
>
>             at
> java.util.AbstractList$Itr.checkForComodification(AbstractList.java(Inlined
> Compiled Code))
>
>             at java.util.AbstractList$Itr.next(AbstractList.java(Compiled
> Code))
>
>             at
> org.apache.velocity.runtime.directive.Foreach.render(Foreach.java:203)
>
>             at
> org.apache.velocity.runtime.parser.node.ASTDirective.render(ASTDirective.java:152)
>
>             at
> org.apache.velocity.runtime.parser.node.ASTBlock.render(ASTBlock.java(Compiled
> Code))
>
>             at
> org.apache.velocity.runtime.parser.node.ASTIfStatement.render(ASTIfStatement.java(Compiled
> Code))
>
>             at
> org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java(Compiled
> Code))
>
>             at
> org.apache.velocity.runtime.directive.VelocimacroProxy.render(VelocimacroProxy.java:210)
>
>             at
> org.apache.velocity.runtime.parser.node.ASTDirective.render(ASTDirective.java:152)
>
>             at
> org.apache.velocity.runtime.parser.node.SimpleNode.render(SimpleNode.java(Compiled
> Code))
>
>             at
> org.apache.velocity.Template.merge(Template.java(Compiled
> Code))
>
>             at
> net.sf.navigator.displayer.VelocityMenuDisplayer.displayComponents(VelocityMenuDisplayer.java(Compiled
> Code))
>
>             at
> net.sf.navigator.displayer.VelocityMenuDisplayer.display(VelocityMenuDisplayer.java:99)
>
>             at
> net.sf.navigator.taglib.DisplayMenuTag.doStartTag(DisplayMenuTag.java:130)
>
>             at
> com.ibm._jsp._side_5F_secure._jspx_meth_menu_displayMenu_3(_side_5F_secure.java:180)
>
>             at
> com.ibm._jsp._side_5F_secure._jspx_meth_menu_useMenuDisplayer_0(_side_5F_secure.java:230)
>
>             at
> com.ibm._jsp._side_5F_secure._jspService(_side_5F_secure.java:104)
>
>             at
> com.ibm.ws.jsp.runtime.HttpJspBase.service(HttpJspBase.java:88)
>
>             at
> javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
>
>             at
> com.ibm.ws.cache.servlet.ServletWrapper.serviceProxied(ServletWrapper.java:242)
>
>             at
> com.ibm.ws.cache.servlet.CacheHook.handleFragment(CacheHook.java:326)
>
>             at
> com.ibm.ws.cache.servlet.CacheHook.handleServlet(CacheHook.java:211)
>
>             at
> com.ibm.ws.cache.servlet.ServletWrapper.service(ServletWrapper.java:224)
>
>             at
> com.ibm.ws.webcontainer.servlet.ServletWrapper.service(ServletWrapper.java:1221)
>
>             at
> com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:630)
>
>             at
> com.ibm.wsspi.webcontainer.servlet.GenericServletWrapper.handleRequest(GenericServletWrapper.java:117)
>
>             at
> com.ibm.ws.jsp.webcontainerext.JSPExtensionServletWrapper.handleRequest(JSPExtensionServletWrapper.java:173)
>
>             at
> com.ibm.ws.webcontainer.webapp.WebAppRequestDispatcher.include(WebAppRequestDispatcher.java:579)
>
>             at
> org.apache.jasper.runtime.JspRuntimeLibrary.include(JspRuntimeLibrary.java:1034)
>
>             at
> org.apache.jasper.runtime.PageContextImpl.include(PageContextImpl.java:475)
>
>             at
> org.apache.struts.tiles.TilesUtilImpl.doInclude(TilesUtilImpl.java:101)
>
>             at
> org.apache.struts.tiles.TilesUtil.doInclude(TilesUtil.java:137)
>
>             at
> org.apache.struts.taglib.tiles.InsertTag.doInclude(InsertTag.java:758)
>
>             at
> org.apache.struts.taglib.tiles.InsertTag$InsertHandler.doEndTag(InsertTag.java:890)
>
>             at
> org.apache.struts.taglib.tiles.InsertTag.doEndTag(InsertTag.java:460)
>
>             at
> com.ibm._jsp._base_5F_summary._jspx_meth_tiles_get_2(_base_5F_summary.java:575)
>
>             at
> com.ibm._jsp._base_5F_summary._jspService(_base_5F_summary.java:292)
>
>             at
> com.ibm.ws.jsp.runtime.HttpJspBase.service(HttpJspBase.java:88)
>
>             at
> javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
>
>             at
> com.ibm.ws.cache.servlet.ServletWrapper.serviceProxied(ServletWrapper.java:242)
>
>             at
> com.ibm.ws.cache.servlet.CacheHook.handleFragment(CacheHook.java:326)
>
>             at
> com.ibm.ws.cache.servlet.CacheHook.handleServlet(CacheHook.java:211)
>
>             at
> com.ibm.ws.cache.servlet.ServletWrapper.service(ServletWrapper.java:224)
>
>             at
> com.ibm.ws.webcontainer.servlet.ServletWrapper.service(ServletWrapper.java:1221)
>
>             at
> com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:630)
>
>             at
> com.ibm.wsspi.webcontainer.servlet.GenericServletWrapper.handleRequest(GenericServletWrapper.java:117)
>
>             at
> com.ibm.ws.jsp.webcontainerext.JSPExtensionServletWrapper.handleRequest(JSPExtensionServletWrapper.java:173)
>
>             at
> com.ibm.ws.webcontainer.webapp.WebAppRequestDispatcher.forward(WebAppRequestDispatcher.java:262)
>
>             at
> org.apache.struts.action.RequestProcessor.doForward(RequestProcessor.java:1056)
>
>             at
> org.apache.struts.tiles.TilesRequestProcessor.doForward(TilesRequestProcessor.java:261)
>
>             at
> org.apache.struts.tiles.TilesRequestProcessor.processTilesDefinition(TilesRequestProcessor.java:237)
>
>             at
> org.apache.struts.tiles.TilesRequestProcessor.internalModuleRelativeForward(TilesRequestProcessor.java:339)
>
>             at
> org.apache.struts.action.RequestProcessor.processForward(RequestProcessor.java:553)
>
>             at
> org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:211)
>
>             at
> org.apache.struts.action.ActionServlet.process(ActionServlet.java:1164)
>
>             at
> org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:397)
>
>             at
> javax.servlet.http.HttpServlet.service(HttpServlet.java:743)
>
>             at
> javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
>
>             at
> com.ibm.ws.cache.servlet.ServletWrapper.serviceProxied(ServletWrapper.java:242)
>
>             at
> com.ibm.ws.cache.servlet.CacheHook.handleFragment(CacheHook.java:326)
>
>             at
> com.ibm.ws.cache.servlet.CacheHook.handleServlet(CacheHook.java:211)
>
>             at
> com.ibm.ws.cache.servlet.ServletWrapper.service(ServletWrapper.java:224)
>
>             at
> com.ibm.ws.webcontainer.servlet.ServletWrapper.service(ServletWrapper.java:1221)
>
>             at
> com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:630)
>
>             at
> com.ibm.ws.webcontainer.webapp.WebAppRequestDispatcher.forward(WebAppRequestDispatcher.java:262)
>
>             at
> org.apache.struts.action.RequestProcessor.doForward(RequestProcessor.java:1056)
>
>             at
> org.apache.struts.tiles.TilesRequestProcessor.doForward(TilesRequestProcessor.java:261)
>
>             at
> org.apache.struts.action.RequestProcessor.processForwardConfig(RequestProcessor.java:388)
>
>             at
> org.apache.struts.tiles.TilesRequestProcessor.processForwardConfig(TilesRequestProcessor.java:316)
>
>             at
> org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:231)
>
>             at
> org.apache.struts.action.ActionServlet.process(ActionServlet.java:1164)
>
>             at
> org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:397)
>
>             at
> javax.servlet.http.HttpServlet.service(HttpServlet.java:743)
>
>             at
> javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
>
>             at
> com.ibm.ws.cache.servlet.ServletWrapper.serviceProxied(ServletWrapper.java:242)
>
>             at
> com.ibm.ws.cache.servlet.CacheHook.handleFragment(CacheHook.java:326)
>
>             at
> com.ibm.ws.cache.servlet.CacheHook.handleServlet(CacheHook.java:211)
>
>             at
> com.ibm.ws.cache.servlet.ServletWrapper.service(ServletWrapper.java:224)
>
>             at
> com.ibm.ws.webcontainer.servlet.ServletWrapper.service(ServletWrapper.java:1221)
>
>             at
> com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:630)
>
>             at
> com.ibm.ws.webcontainer.webapp.WebApp.handleRequest(WebApp.java:2872)
>
>             at
> com.ibm.ws.webcontainer.webapp.WebGroup.handleRequest(WebGroup.java:220)
>
>             at
> com.ibm.ws.webcontainer.VirtualHost.handleRequest(VirtualHost.java:204)
>
>             at
> com.ibm.ws.webcontainer.WebContainer.handleRequest(WebContainer.java:1779)
>
>             at
> com.ibm.ws.webcontainer.channel.WCChannelLink.ready(WCChannelLink.java:77)
>
>             at
> com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleDiscrimination(HttpInboundLink.java:466)
>
>             at
> com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleNewInformation(HttpInboundLink.java:405)
>
>             at
> com.ibm.ws.http.channel.inbound.impl.HttpICLReadCallback.complete(HttpICLReadCallback.java:104)
>
>             at
> com.ibm.ws.tcp.channel.impl.WorkQueueManager.requestComplete(WorkQueueManager.java(Compiled
> Code))
>
>             at
> com.ibm.ws.tcp.channel.impl.WorkQueueManager.attemptIO(WorkQueueManager.java(Compiled
> Code))
>
>             at
> com.ibm.ws.tcp.channel.impl.WorkQueueManager.workerRun(WorkQueueManager.java:941)
>
>             at
> com.ibm.ws.tcp.channel.impl.WorkQueueManager$Worker.run(WorkQueueManager.java:1028)
>
>             at
> com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:1394)
>
>