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ConcurrentModificationException on DefaultConverterManager.getConverterAssignableFrom

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Parent Message unknown ConcurrentModificationException on DefaultConverterManager.getConverterAssignableFrom

by Fabio Collini :: Rate this Message:

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Hi, I am using dwr 2.0.2 in my web application on a websphere 6.1. Today I have this exception and I had to restart server to fix it:

org.directwebremoting.extend.MarshallException: Error marshalling it.omniagroup.lgi.filtri.model.beansext.Regola: concurrent access to HashMap attempted by Thread[WebContainer : 1,5,main]. See the logs for more details.
at org.directwebremoting.convert.BasicObjectConverter.convertOutbound(BasicObjectConverter.java:200)
at org.directwebremoting.dwrp.DefaultConverterManager.convertOutbound(DefaultConverterManager.java:192)
at org.directwebremoting.convert.BasicObjectConverter.convertOutbound(BasicObjectConverter.java:189)
at org.directwebremoting.dwrp.DefaultConverterManager.convertOutbound(DefaultConverterManager.java:192)
at org.directwebremoting.convert.CollectionConverter.convertOutbound(CollectionConverter.java:206)
at it.omniagroup.lgi.utilita.griglia.GrigliaModelPaginatoConverter.convertOutbound(GrigliaModelPaginatoConverter.java:69)
at org.directwebremoting.dwrp.DefaultConverterManager.convertOutbound(DefaultConverterManager.java:192)
at org.directwebremoting.convert.BasicObjectConverter.convertOutbound(BasicObjectConverter.java:189)
at org.directwebremoting.dwrp.DefaultConverterManager.convertOutbound(DefaultConverterManager.java:192)
at org.directwebremoting.convert.CollectionConverter.convertOutbound(CollectionConverter.java:206)
at it.omniagroup.lgi.utilita.griglia.GrigliaModelPaginatoConverter.convertOutbound(GrigliaModelPaginatoConverter.java:69)
at org.directwebremoting.dwrp.DefaultConverterManager.convertOutbound(DefaultConverterManager.java:192)
at org.directwebremoting.extend.ScriptBufferUtil.createOutput(ScriptBufferUtil.java:56)
at org.directwebremoting.dwrp.BaseCallMarshaller$CallScriptConduit.addScript(BaseCallMarshaller.java:512)
at org.directwebremoting.extend.EnginePrivate.remoteHandleCallback(EnginePrivate.java:56)
at org.directwebremoting.dwrp.BaseCallMarshaller.marshallOutbound(BaseCallMarshaller.java:330)
at org.directwebremoting.servlet.PlainCallHandler.handle(PlainCallHandler.java:53)
at org.directwebremoting.servlet.UrlProcessor.handle(UrlProcessor.java:101)
at org.directwebremoting.servlet.DwrServlet.doPost(DwrServlet.java:146)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:763)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
at com.ibm.ws.webcontainer.servlet.ServletWrapper.service(ServletWrapper.java:1095)
at com.ibm.ws.webcontainer.servlet.ServletWrapper.service(ServletWrapper.java:1036)
at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java:145)
at com.opensymphony.module.sitemesh.filter.PageFilter.parsePage(PageFilter.java:119)
at com.opensymphony.module.sitemesh.filter.PageFilter.doFilter(PageFilter.java:55)
at com.ibm.ws.webcontainer.filter.FilterInstanceWrapper.doFilter(FilterInstanceWrapper.java:190)
at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java:130)
at com.ibm.ws.webcontainer.filter.WebAppFilterChain._doFilter(WebAppFilterChain.java:87)
at com.ibm.ws.webcontainer.filter.WebAppFilterManager.doFilter(WebAppFilterManager.java:832)
at com.ibm.ws.webcontainer.filter.WebAppFilterManager.doFilter(WebAppFilterManager.java:679)
at com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:565)
at com.ibm.ws.wswebcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:478)
at com.ibm.ws.webcontainer.servlet.CacheServletWrapper.handleRequest(CacheServletWrapper.java:90)
at com.ibm.ws.webcontainer.WebContainer.handleRequest(WebContainer.java:748)
at com.ibm.ws.wswebcontainer.WebContainer.handleRequest(WebContainer.java:1461)
at com.ibm.ws.webcontainer.channel.WCChannelLink.ready(WCChannelLink.java:118)
at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleDiscrimination(HttpInboundLink.java:458)
at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleNewInformation(HttpInboundLink.java:387)
at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.ready(HttpInboundLink.java:267)
at com.ibm.ws.tcp.channel.impl.NewConnectionInitialReadCallback.sendToDiscriminators(NewConnectionInitialReadCallback.java:214)
at com.ibm.ws.tcp.channel.impl.NewConnectionInitialReadCallback.complete(NewConnectionInitialReadCallback.java:113)
at com.ibm.ws.tcp.channel.impl.AioReadCompletionListener.futureCompleted(AioReadCompletionListener.java:165)
at com.ibm.io.async.AbstractAsyncFuture.invokeCallback(AbstractAsyncFuture.java:217)
at com.ibm.io.async.AsyncChannelFuture.fireCompletionActions(AsyncChannelFuture.java:161)
at com.ibm.io.async.AsyncFuture.completed(AsyncFuture.java:136)
at com.ibm.io.async.ResultHandler.complete(ResultHandler.java:195)
at com.ibm.io.async.ResultHandler.runEventProcessingLoop(ResultHandler.java:743)
at com.ibm.io.async.ResultHandler$2.run(ResultHandler.java:873)
at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:1473)
Caused by: java.util.ConcurrentModificationException: concurrent access to HashMap attempted by Thread[WebContainer : 1,5,main]
at java.util.HashMap.onExit(HashMap.java:226)
at java.util.HashMap.transfer(HashMap.java:690)
at java.util.HashMap.resize(HashMap.java:676)
at java.util.HashMap.addEntry(HashMap.java:1049)
at java.util.HashMap.put(HashMap.java:561)
at org.directwebremoting.dwrp.DefaultConverterManager.getConverterAssignableFrom(DefaultConverterManager.java:406)
at org.directwebremoting.dwrp.DefaultConverterManager.getConverter(DefaultConverterManager.java:302)
at org.directwebremoting.dwrp.DefaultConverterManager.getConverter(DefaultConverterManager.java:234)
at org.directwebremoting.dwrp.DefaultConverterManager.convertOutbound(DefaultConverterManager.java:185)
at org.directwebremoting.convert.BasicObjectConverter.convertOutbound(BasicObjectConverter.java:189)
... 49 more

[10/23/09 7:44:12:338 CEST] 00000040 CollectionCon W org.directwebremoting.util.CommonsLoggingOutput warn Conversion error for it.omniagroup.lgi.utilita.griglia.GrigliaModelPaginato.
                                 org.directwebremoting.extend.MarshallException: Error marshalling it.omniagroup.lgi.filtri.model.beansext.Regola: concurrent access to HashMap attempted by Thread[WebContainer : 6,5,main]. See the logs for more details.
at org.directwebremoting.convert.BasicObjectConverter.convertOutbound(BasicObjectConverter.java:200)
at org.directwebremoting.dwrp.DefaultConverterManager.convertOutbound(DefaultConverterManager.java:192)
at org.directwebremoting.convert.BasicObjectConverter.convertOutbound(BasicObjectConverter.java:189)
at org.directwebremoting.dwrp.DefaultConverterManager.convertOutbound(DefaultConverterManager.java:192)
at org.directwebremoting.convert.CollectionConverter.convertOutbound(CollectionConverter.java:206)
at it.omniagroup.lgi.utilita.griglia.GrigliaModelPaginatoConverter.convertOutbound(GrigliaModelPaginatoConverter.java:69)
at org.directwebremoting.dwrp.DefaultConverterManager.convertOutbound(DefaultConverterManager.java:192)
at org.directwebremoting.convert.BasicObjectConverter.convertOutbound(BasicObjectConverter.java:189)
at org.directwebremoting.dwrp.DefaultConverterManager.convertOutbound(DefaultConverterManager.java:192)
at org.directwebremoting.convert.CollectionConverter.convertOutbound(CollectionConverter.java:206)
at it.omniagroup.lgi.utilita.griglia.GrigliaModelPaginatoConverter.convertOutbound(GrigliaModelPaginatoConverter.java:69)
at org.directwebremoting.dwrp.DefaultConverterManager.convertOutbound(DefaultConverterManager.java:192)
at org.directwebremoting.extend.ScriptBufferUtil.createOutput(ScriptBufferUtil.java:56)
at org.directwebremoting.dwrp.BaseCallMarshaller$CallScriptConduit.addScript(BaseCallMarshaller.java:512)
at org.directwebremoting.extend.EnginePrivate.remoteHandleCallback(EnginePrivate.java:56)
at org.directwebremoting.dwrp.BaseCallMarshaller.marshallOutbound(BaseCallMarshaller.java:330)
at org.directwebremoting.servlet.PlainCallHandler.handle(PlainCallHandler.java:53)
at org.directwebremoting.servlet.UrlProcessor.handle(UrlProcessor.java:101)
at org.directwebremoting.servlet.DwrServlet.doPost(DwrServlet.java:146)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:763)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
at com.ibm.ws.webcontainer.servlet.ServletWrapper.service(ServletWrapper.java:1095)
at com.ibm.ws.webcontainer.servlet.ServletWrapper.service(ServletWrapper.java:1036)
at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java:145)
at com.opensymphony.module.sitemesh.filter.PageFilter.parsePage(PageFilter.java:119)
at com.opensymphony.module.sitemesh.filter.PageFilter.doFilter(PageFilter.java:55)
at com.ibm.ws.webcontainer.filter.FilterInstanceWrapper.doFilter(FilterInstanceWrapper.java:190)
at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java:130)
at com.ibm.ws.webcontainer.filter.WebAppFilterChain._doFilter(WebAppFilterChain.java:87)
at com.ibm.ws.webcontainer.filter.WebAppFilterManager.doFilter(WebAppFilterManager.java:832)
at com.ibm.ws.webcontainer.filter.WebAppFilterManager.doFilter(WebAppFilterManager.java:679)
at com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:565)
at com.ibm.ws.wswebcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:478)
at com.ibm.ws.webcontainer.servlet.CacheServletWrapper.handleRequest(CacheServletWrapper.java:90)
at com.ibm.ws.webcontainer.WebContainer.handleRequest(WebContainer.java:748)
at com.ibm.ws.wswebcontainer.WebContainer.handleRequest(WebContainer.java:1461)
at com.ibm.ws.webcontainer.channel.WCChannelLink.ready(WCChannelLink.java:118)
at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleDiscrimination(HttpInboundLink.java:458)
at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleNewInformation(HttpInboundLink.java:387)
at com.ibm.ws.http.channel.inbound.impl.HttpICLReadCallback.complete(HttpICLReadCallback.java:102)
at com.ibm.ws.tcp.channel.impl.AioReadCompletionListener.futureCompleted(AioReadCompletionListener.java:165)
at com.ibm.io.async.AbstractAsyncFuture.invokeCallback(AbstractAsyncFuture.java:217)
at com.ibm.io.async.AsyncChannelFuture.fireCompletionActions(AsyncChannelFuture.java:161)
at com.ibm.io.async.AsyncFuture.completed(AsyncFuture.java:136)
at com.ibm.io.async.ResultHandler.complete(ResultHandler.java:195)
at com.ibm.io.async.ResultHandler.runEventProcessingLoop(ResultHandler.java:743)
at com.ibm.io.async.ResultHandler$2.run(ResultHandler.java:873)
at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:1473)
Caused by: java.util.ConcurrentModificationException: concurrent access to HashMap attempted by Thread[WebContainer : 6,5,main]
at java.util.HashMap.onEntry(HashMap.java:214)
at java.util.HashMap.transfer(HashMap.java:686)
at java.util.HashMap.resize(HashMap.java:676)
at java.util.HashMap.addEntry(HashMap.java:1049)
at java.util.HashMap.put(HashMap.java:561)
at org.directwebremoting.dwrp.DefaultConverterManager.getConverterAssignableFrom(DefaultConverterManager.java:406)
at org.directwebremoting.dwrp.DefaultConverterManager.getConverter(DefaultConverterManager.java:302)
at org.directwebremoting.dwrp.DefaultConverterManager.getConverter(DefaultConverterManager.java:234)
at org.directwebremoting.dwrp.DefaultConverterManager.convertOutbound(DefaultConverterManager.java:185)
at org.directwebremoting.convert.BasicObjectConverter.convertOutbound(BasicObjectConverter.java:189)
... 47 more

I think that converters map declared at line 439 should be syncrohized.
Best regards
Fabio

--

OmniaSoftware ® s.r.l. 
Dott. Fabio Collini
(Analista Programmatore) 
Via Melloni, 29 - 50019 Sesto F.no (FI) 
Tel. 0554200158 int.208 
fcollini@...
sceri@...http://www.omniagroup.it/

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Re: ConcurrentModificationException on DefaultConverterManager.getConverterAssignableFrom

by davidmarginian :: Rate this Message:

Reply to Author | View Threaded | Show Only this Message

Fabio,
   I took a quick look at the latest 2.x source (which is not 2.0.2).  I didn't see anything that looked alarming - I did a search online and so a few things that may indicate bugs in WebSphere but I can' confirm or deny this.  Any one else have thoughts here?

On Fri, Oct 23, 2009 at 4:51 AM, Fabio Collini <fcollini@...> wrote:
Hi, I am using dwr 2.0.2 in my web application on a websphere 6.1. Today I have this exception and I had to restart server to fix it:

org.directwebremoting.extend.MarshallException: Error marshalling it.omniagroup.lgi.filtri.model.beansext.Regola: concurrent access to HashMap attempted by Thread[WebContainer : 1,5,main]. See the logs for more details.
at org.directwebremoting.convert.BasicObjectConverter.convertOutbound(BasicObjectConverter.java:200)
at org.directwebremoting.dwrp.DefaultConverterManager.convertOutbound(DefaultConverterManager.java:192)
at org.directwebremoting.convert.BasicObjectConverter.convertOutbound(BasicObjectConverter.java:189)
at org.directwebremoting.dwrp.DefaultConverterManager.convertOutbound(DefaultConverterManager.java:192)
at org.directwebremoting.convert.CollectionConverter.convertOutbound(CollectionConverter.java:206)
at it.omniagroup.lgi.utilita.griglia.GrigliaModelPaginatoConverter.convertOutbound(GrigliaModelPaginatoConverter.java:69)
at org.directwebremoting.dwrp.DefaultConverterManager.convertOutbound(DefaultConverterManager.java:192)
at org.directwebremoting.convert.BasicObjectConverter.convertOutbound(BasicObjectConverter.java:189)
at org.directwebremoting.dwrp.DefaultConverterManager.convertOutbound(DefaultConverterManager.java:192)
at org.directwebremoting.convert.CollectionConverter.convertOutbound(CollectionConverter.java:206)
at it.omniagroup.lgi.utilita.griglia.GrigliaModelPaginatoConverter.convertOutbound(GrigliaModelPaginatoConverter.java:69)
at org.directwebremoting.dwrp.DefaultConverterManager.convertOutbound(DefaultConverterManager.java:192)
at org.directwebremoting.extend.ScriptBufferUtil.createOutput(ScriptBufferUtil.java:56)
at org.directwebremoting.dwrp.BaseCallMarshaller$CallScriptConduit.addScript(BaseCallMarshaller.java:512)
at org.directwebremoting.extend.EnginePrivate.remoteHandleCallback(EnginePrivate.java:56)
at org.directwebremoting.dwrp.BaseCallMarshaller.marshallOutbound(BaseCallMarshaller.java:330)
at org.directwebremoting.servlet.PlainCallHandler.handle(PlainCallHandler.java:53)
at org.directwebremoting.servlet.UrlProcessor.handle(UrlProcessor.java:101)
at org.directwebremoting.servlet.DwrServlet.doPost(DwrServlet.java:146)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:763)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
at com.ibm.ws.webcontainer.servlet.ServletWrapper.service(ServletWrapper.java:1095)
at com.ibm.ws.webcontainer.servlet.ServletWrapper.service(ServletWrapper.java:1036)
at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java:145)
at com.opensymphony.module.sitemesh.filter.PageFilter.parsePage(PageFilter.java:119)
at com.opensymphony.module.sitemesh.filter.PageFilter.doFilter(PageFilter.java:55)
at com.ibm.ws.webcontainer.filter.FilterInstanceWrapper.doFilter(FilterInstanceWrapper.java:190)
at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java:130)
at com.ibm.ws.webcontainer.filter.WebAppFilterChain._doFilter(WebAppFilterChain.java:87)
at com.ibm.ws.webcontainer.filter.WebAppFilterManager.doFilter(WebAppFilterManager.java:832)
at com.ibm.ws.webcontainer.filter.WebAppFilterManager.doFilter(WebAppFilterManager.java:679)
at com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:565)
at com.ibm.ws.wswebcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:478)
at com.ibm.ws.webcontainer.servlet.CacheServletWrapper.handleRequest(CacheServletWrapper.java:90)
at com.ibm.ws.webcontainer.WebContainer.handleRequest(WebContainer.java:748)
at com.ibm.ws.wswebcontainer.WebContainer.handleRequest(WebContainer.java:1461)
at com.ibm.ws.webcontainer.channel.WCChannelLink.ready(WCChannelLink.java:118)
at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleDiscrimination(HttpInboundLink.java:458)
at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleNewInformation(HttpInboundLink.java:387)
at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.ready(HttpInboundLink.java:267)
at com.ibm.ws.tcp.channel.impl.NewConnectionInitialReadCallback.sendToDiscriminators(NewConnectionInitialReadCallback.java:214)
at com.ibm.ws.tcp.channel.impl.NewConnectionInitialReadCallback.complete(NewConnectionInitialReadCallback.java:113)
at com.ibm.ws.tcp.channel.impl.AioReadCompletionListener.futureCompleted(AioReadCompletionListener.java:165)
at com.ibm.io.async.AbstractAsyncFuture.invokeCallback(AbstractAsyncFuture.java:217)
at com.ibm.io.async.AsyncChannelFuture.fireCompletionActions(AsyncChannelFuture.java:161)
at com.ibm.io.async.AsyncFuture.completed(AsyncFuture.java:136)
at com.ibm.io.async.ResultHandler.complete(ResultHandler.java:195)
at com.ibm.io.async.ResultHandler.runEventProcessingLoop(ResultHandler.java:743)
at com.ibm.io.async.ResultHandler$2.run(ResultHandler.java:873)
at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:1473)
Caused by: java.util.ConcurrentModificationException: concurrent access to HashMap attempted by Thread[WebContainer : 1,5,main]
at java.util.HashMap.onExit(HashMap.java:226)
at java.util.HashMap.transfer(HashMap.java:690)
at java.util.HashMap.resize(HashMap.java:676)
at java.util.HashMap.addEntry(HashMap.java:1049)
at java.util.HashMap.put(HashMap.java:561)
at org.directwebremoting.dwrp.DefaultConverterManager.getConverterAssignableFrom(DefaultConverterManager.java:406)
at org.directwebremoting.dwrp.DefaultConverterManager.getConverter(DefaultConverterManager.java:302)
at org.directwebremoting.dwrp.DefaultConverterManager.getConverter(DefaultConverterManager.java:234)
at org.directwebremoting.dwrp.DefaultConverterManager.convertOutbound(DefaultConverterManager.java:185)
at org.directwebremoting.convert.BasicObjectConverter.convertOutbound(BasicObjectConverter.java:189)
... 49 more

[10/23/09 7:44:12:338 CEST] 00000040 CollectionCon W org.directwebremoting.util.CommonsLoggingOutput warn Conversion error for it.omniagroup.lgi.utilita.griglia.GrigliaModelPaginato.
                                 org.directwebremoting.extend.MarshallException: Error marshalling it.omniagroup.lgi.filtri.model.beansext.Regola: concurrent access to HashMap attempted by Thread[WebContainer : 6,5,main]. See the logs for more details.
at org.directwebremoting.convert.BasicObjectConverter.convertOutbound(BasicObjectConverter.java:200)
at org.directwebremoting.dwrp.DefaultConverterManager.convertOutbound(DefaultConverterManager.java:192)
at org.directwebremoting.convert.BasicObjectConverter.convertOutbound(BasicObjectConverter.java:189)
at org.directwebremoting.dwrp.DefaultConverterManager.convertOutbound(DefaultConverterManager.java:192)
at org.directwebremoting.convert.CollectionConverter.convertOutbound(CollectionConverter.java:206)
at it.omniagroup.lgi.utilita.griglia.GrigliaModelPaginatoConverter.convertOutbound(GrigliaModelPaginatoConverter.java:69)
at org.directwebremoting.dwrp.DefaultConverterManager.convertOutbound(DefaultConverterManager.java:192)
at org.directwebremoting.convert.BasicObjectConverter.convertOutbound(BasicObjectConverter.java:189)
at org.directwebremoting.dwrp.DefaultConverterManager.convertOutbound(DefaultConverterManager.java:192)
at org.directwebremoting.convert.CollectionConverter.convertOutbound(CollectionConverter.java:206)
at it.omniagroup.lgi.utilita.griglia.GrigliaModelPaginatoConverter.convertOutbound(GrigliaModelPaginatoConverter.java:69)
at org.directwebremoting.dwrp.DefaultConverterManager.convertOutbound(DefaultConverterManager.java:192)
at org.directwebremoting.extend.ScriptBufferUtil.createOutput(ScriptBufferUtil.java:56)
at org.directwebremoting.dwrp.BaseCallMarshaller$CallScriptConduit.addScript(BaseCallMarshaller.java:512)
at org.directwebremoting.extend.EnginePrivate.remoteHandleCallback(EnginePrivate.java:56)
at org.directwebremoting.dwrp.BaseCallMarshaller.marshallOutbound(BaseCallMarshaller.java:330)
at org.directwebremoting.servlet.PlainCallHandler.handle(PlainCallHandler.java:53)
at org.directwebremoting.servlet.UrlProcessor.handle(UrlProcessor.java:101)
at org.directwebremoting.servlet.DwrServlet.doPost(DwrServlet.java:146)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:763)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
at com.ibm.ws.webcontainer.servlet.ServletWrapper.service(ServletWrapper.java:1095)
at com.ibm.ws.webcontainer.servlet.ServletWrapper.service(ServletWrapper.java:1036)
at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java:145)
at com.opensymphony.module.sitemesh.filter.PageFilter.parsePage(PageFilter.java:119)
at com.opensymphony.module.sitemesh.filter.PageFilter.doFilter(PageFilter.java:55)
at com.ibm.ws.webcontainer.filter.FilterInstanceWrapper.doFilter(FilterInstanceWrapper.java:190)
at com.ibm.ws.webcontainer.filter.WebAppFilterChain.doFilter(WebAppFilterChain.java:130)
at com.ibm.ws.webcontainer.filter.WebAppFilterChain._doFilter(WebAppFilterChain.java:87)
at com.ibm.ws.webcontainer.filter.WebAppFilterManager.doFilter(WebAppFilterManager.java:832)
at com.ibm.ws.webcontainer.filter.WebAppFilterManager.doFilter(WebAppFilterManager.java:679)
at com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:565)
at com.ibm.ws.wswebcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:478)
at com.ibm.ws.webcontainer.servlet.CacheServletWrapper.handleRequest(CacheServletWrapper.java:90)
at com.ibm.ws.webcontainer.WebContainer.handleRequest(WebContainer.java:748)
at com.ibm.ws.wswebcontainer.WebContainer.handleRequest(WebContainer.java:1461)
at com.ibm.ws.webcontainer.channel.WCChannelLink.ready(WCChannelLink.java:118)
at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleDiscrimination(HttpInboundLink.java:458)
at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleNewInformation(HttpInboundLink.java:387)
at com.ibm.ws.http.channel.inbound.impl.HttpICLReadCallback.complete(HttpICLReadCallback.java:102)
at com.ibm.ws.tcp.channel.impl.AioReadCompletionListener.futureCompleted(AioReadCompletionListener.java:165)
at com.ibm.io.async.AbstractAsyncFuture.invokeCallback(AbstractAsyncFuture.java:217)
at com.ibm.io.async.AsyncChannelFuture.fireCompletionActions(AsyncChannelFuture.java:161)
at com.ibm.io.async.AsyncFuture.completed(AsyncFuture.java:136)
at com.ibm.io.async.ResultHandler.complete(ResultHandler.java:195)
at com.ibm.io.async.ResultHandler.runEventProcessingLoop(ResultHandler.java:743)
at com.ibm.io.async.ResultHandler$2.run(ResultHandler.java:873)
at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:1473)
Caused by: java.util.ConcurrentModificationException: concurrent access to HashMap attempted by Thread[WebContainer : 6,5,main]
at java.util.HashMap.onEntry(HashMap.java:214)
at java.util.HashMap.transfer(HashMap.java:686)
at java.util.HashMap.resize(HashMap.java:676)
at java.util.HashMap.addEntry(HashMap.java:1049)
at java.util.HashMap.put(HashMap.java:561)
at org.directwebremoting.dwrp.DefaultConverterManager.getConverterAssignableFrom(DefaultConverterManager.java:406)
at org.directwebremoting.dwrp.DefaultConverterManager.getConverter(DefaultConverterManager.java:302)
at org.directwebremoting.dwrp.DefaultConverterManager.getConverter(DefaultConverterManager.java:234)
at org.directwebremoting.dwrp.DefaultConverterManager.convertOutbound(DefaultConverterManager.java:185)
at org.directwebremoting.convert.BasicObjectConverter.convertOutbound(BasicObjectConverter.java:189)
... 47 more

I think that converters map declared at line 439 should be syncrohized.
Best regards
Fabio

--

OmniaSoftware ® s.r.l. 
Dott. Fabio Collini
(Analista Programmatore) 
Via Melloni, 29 - 50019 Sesto F.no (FI) 
Tel. 0554200158 int.208 
fcollini@...
sceri@...http://www.omniagroup.it/

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Re: ConcurrentModificationException on DefaultConverterManager.getConverterAssignableFrom

by tpeierls :: Rate this Message:

Reply to Author | View Threaded | Show Only this Message

In the current 2.x source (and on the trunk), converters is a non-final, non-volatile field, initialized with an empty HashMap. Last time I looked at this code, I assumed that all mutative calls that affect converters (addConverter and setConverters) were confined to a single thread during servlet init, after which all access to converters was non-mutative and made during requests -- in which case, everything would be fine. (I'm taking the standard view that there is a happens-before edge between servlet init and servlet request handling.)

However, Fabio's example makes it clear that there can be mutative access to converters during request handling as a result of calls to getConverterAssignableFrom. That means all bets are off and that this is a pretty serious concurrency bug.

I think the following steps should be taken for the converters field (and other fields like it):

  • The converters field should be final.
  • The converters field should be initialized with an empty ConcurrentHashMap. For the 2.x branch, if Java 1.4 compatibility is still required, use a plain HashMap wrapped with Collections.synchronizedMap().
  • The setConverters method should be implemented as 
        synchronized (this.converters) {
        this.converters.clear();
        this.converters.putAll(converters);
    }

I posted some rules for thread-safety that might prove useful.

davidmarginian wrote:
Fabio, I took a quick look at the latest 2.x source (which is not 2.0.2). I didn't see anything that looked alarming - I did a search online and so a few things that may indicate bugs in WebSphere but I can' confirm or deny this. Any one else have thoughts here?

RE: ConcurrentModificationException on DefaultConverterManager.getConverterAssignableFrom

by mikewse :: Rate this Message:

Reply to Author | View Threaded | Show Only this Message

Yes, I haven't noticed this before but it is pretty clear that DefaultConverterManager.getConverterAssignableFrom() mutates the converters field along the way. It caches results of previous lookups, and this happens in (after-init) run-time.
 
Btw, DWR 2.x is built against Java 1.3.
 
Fabio: would you mind adding this as a bug to our JIRA? I think we will want to fix it for 2.0.6 and 3.0RC2.
 
Best regards
Mike Wilson

From: tpeierls [mailto:tim@...]
Sent: den 23 oktober 2009 15:58
To: dev@...
Subject: Re: [dwr-dev] ConcurrentModificationException on DefaultConverterManager.getConverterAssignableFrom

In the current 2.x source (and on the trunk), converters is a non-final, non-volatile field, initialized with an empty HashMap. Last time I looked at this code, I assumed that all mutative calls that affect converters (addConverter and setConverters) were confined to a single thread during servlet init, after which all access to converters was non-mutative and made during requests -- in which case, everything would be fine. (I'm taking the standard view that there is a happens-before edge between servlet init and servlet request handling.)

However, Fabio's example makes it clear that there can be mutative access to converters during request handling as a result of calls to getConverterAssignableFrom. That means all bets are off and that this is a pretty serious concurrency bug.

I think the following steps should be taken for the converters field (and other fields like it):

  • The converters field should be final.
  • The converters field should be initialized with an empty ConcurrentHashMap. For the 2.x branch, if Java 1.4 compatibility is still required, use a plain HashMap wrapped with Collections.synchronizedMap().
  • The setConverters method should be implemented as 
        synchronized (this.converters) {
        this.converters.clear();
        this.converters.putAll(converters);
    }

I posted some rules for thread-safety that might prove useful.

davidmarginian wrote:
Fabio, I took a quick look at the latest 2.x source (which is not 2.0.2). I didn't see anything that looked alarming - I did a search online and so a few things that may indicate bugs in WebSphere but I can' confirm or deny this. Any one else have thoughts here?

View this message in context: Re: ConcurrentModificationException on DefaultConverterManager.getConverterAssignableFrom
Sent from the DWR - Dev mailing list archive at Nabble.com.

Re: ConcurrentModificationException on DefaultConverterManager.getConverterAssignableFrom

by davidmarginian :: Rate this Message:

Reply to Author | View Threaded | Show Only this Message

I am really surprised we haven't spotted this before.  We were wanting to push out a 2.0.6 release anyway so I will work on this and hopefully push something out early-mid next week.  

On Fri, Oct 23, 2009 at 8:31 AM, Mike Wilson <mikewse@...> wrote:
Yes, I haven't noticed this before but it is pretty clear that DefaultConverterManager.getConverterAssignableFrom() mutates the converters field along the way. It caches results of previous lookups, and this happens in (after-init) run-time.
 
Btw, DWR 2.x is built against Java 1.3.
 
Fabio: would you mind adding this as a bug to our JIRA? I think we will want to fix it for 2.0.6 and 3.0RC2.
 
Best regards
Mike Wilson

From: tpeierls [mailto:tim@...]
Sent: den 23 oktober 2009 15:58
To: dev@...
Subject: Re: [dwr-dev] ConcurrentModificationException on DefaultConverterManager.getConverterAssignableFrom

In the current 2.x source (and on the trunk), converters is a non-final, non-volatile field, initialized with an empty HashMap. Last time I looked at this code, I assumed that all mutative calls that affect converters (addConverter and setConverters) were confined to a single thread during servlet init, after which all access to converters was non-mutative and made during requests -- in which case, everything would be fine. (I'm taking the standard view that there is a happens-before edge between servlet init and servlet request handling.)

However, Fabio's example makes it clear that there can be mutative access to converters during request handling as a result of calls to getConverterAssignableFrom. That means all bets are off and that this is a pretty serious concurrency bug.

I think the following steps should be taken for the converters field (and other fields like it):

  • The converters field should be final.
  • The converters field should be initialized with an empty ConcurrentHashMap. For the 2.x branch, if Java 1.4 compatibility is still required, use a plain HashMap wrapped with Collections.synchronizedMap().
  • The setConverters method should be implemented as 
        synchronized (this.converters) {
        this.converters.clear();
        this.converters.putAll(converters);
    }

I posted some rules for thread-safety that might prove useful.

davidmarginian wrote:
Fabio, I took a quick look at the latest 2.x source (which is not 2.0.2). I didn't see anything that looked alarming - I did a search online and so a few things that may indicate bugs in WebSphere but I can' confirm or deny this. Any one else have thoughts here?

View this message in context: Re: ConcurrentModificationException on DefaultConverterManager.getConverterAssignableFrom
Sent from the DWR - Dev mailing list archive at Nabble.com.

Re: ConcurrentModificationException on DefaultConverterManager.getConverterAssignableFrom

by tpeierls :: Rate this Message:

Reply to Author | View Threaded | Show Only this Message

And remember this is not just a 2.x issue; it's present in the trunk, too.

I'm dismayed because there are probably a zillion places where DWR has non-final, non-volatile, unguarded references to non-thread-safe objects, and now they are all called into question. I can't believe I let myself relax into thinking everything was OK. :-(

--tim

davidmarginian wrote:
I am really surprised we haven't spotted this before.  We were wanting to
push out a 2.0.6 release anyway so I will work on this and hopefully push
something out early-mid next week.

On Fri, Oct 23, 2009 at 8:31 AM, Mike Wilson <mikewse@hotmail.com> wrote:

>  Yes, I haven't noticed this before but it is pretty clear that
> DefaultConverterManager.getConverterAssignableFrom() mutates the converters
> field along the way. It caches results of previous lookups, and this happens
> in (after-init) run-time.

Re: ConcurrentModificationException on DefaultConverterManager.getConverterAssignableFrom

by davidmarginian :: Rate this Message:

Reply to Author | View Threaded | Show Only this Message

http://bugs.directwebremoting.org/jira/browse/DWR-427

tpeierls wrote:

> And remember this is not just a 2.x issue; it's present in the trunk, too.
>
> I'm dismayed because there are probably a zillion places where DWR has
> non-final, non-volatile, unguarded references to non-thread-safe objects,
> and now they are all called into question. I can't believe I let myself
> relax into thinking everything was OK. :-(
>
> --tim
>
>
> davidmarginian wrote:
>  
>> I am really surprised we haven't spotted this before.  We were wanting to
>> push out a 2.0.6 release anyway so I will work on this and hopefully push
>> something out early-mid next week.
>>
>> On Fri, Oct 23, 2009 at 8:31 AM, Mike Wilson <mikewse@...> wrote:
>>
>>    
>>>  Yes, I haven't noticed this before but it is pretty clear that
>>> DefaultConverterManager.getConverterAssignableFrom() mutates the
>>> converters
>>> field along the way. It caches results of previous lookups, and this
>>> happens
>>> in (after-init) run-time.
>>>      
>
>  



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