数据表上的 JSF ConcurrentModificationException

Question

我们最近发生了中断，在我们的应用程序的日志中，我们可以看到这个异常。 看起来像primefaces正在排序时正在修改表中的数据¿这怎么可能？

这是不经常发生的事情，它只是在生产环境中发生过一次。 同样的堆栈跟踪也会在几秒钟内重复十次或更多次。

05-Jul-2022 19:13:53.583 SEVERE [http-nio-8080-exec-746] com.sun.faces.application.view.FaceletViewHandlingStrategy.handleRenderException Error Rendering View[/pages/example.xhtml]
java.util.ConcurrentModificationException
    at java.util.ArrayList.sort(ArrayList.java:1466)
    at java.util.Collections.sort(Collections.java:177)
    at org.primefaces.component.datatable.feature.SortFeature.singleSort(SortFeature.java:167)
    at org.primefaces.component.datatable.DataTableRenderer.preRender(DataTableRenderer.java:141)
    at org.primefaces.component.datatable.DataTableRenderer.encodeEnd(DataTableRenderer.java:93)
    at javax.faces.component.UIComponentBase.encodeEnd(UIComponentBase.java:949)
    at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1912)
    at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1908)
    at javax.faces.render.Renderer.encodeChildren(Renderer.java:176)
    at javax.faces.component.UIComponentBase.encodeChildren(UIComponentBase.java:918)
    at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1905)
    at com.sun.faces.context.PartialViewContextImpl$PhaseAwareVisitCallback.visit(PartialViewContextImpl.java:638)
    at com.sun.faces.component.visit.PartialVisitContext.invokeVisitCallback(PartialVisitContext.java:183)
    at javax.faces.component.UIForm.visitTree(UIForm.java:405)
    at javax.faces.component.UIComponent.visitTree(UIComponent.java:1747)
    at javax.faces.component.UIComponent.visitTree(UIComponent.java:1747)
    at com.sun.faces.context.PartialViewContextImpl.processComponents(PartialViewContextImpl.java:423)
    at com.sun.faces.context.PartialViewContextImpl.processPartial(PartialViewContextImpl.java:342)
    at org.primefaces.context.PrimePartialViewContext.processPartial(PrimePartialViewContext.java:65)
    at javax.faces.context.PartialViewContextWrapper.processPartial(PartialViewContextWrapper.java:252)
    at org.omnifaces.context.OmniPartialViewContext.processPartial(OmniPartialViewContext.java:122)
    at javax.faces.component.UIViewRoot.encodeChildren(UIViewRoot.java:1124)
    at javax.faces.component.UIComponent.encodeAll(UIComponent.java:1905)
    at com.sun.faces.application.view.FaceletViewHandlingStrategy.renderView(FaceletViewHandlingStrategy.java:465)
    at com.sun.faces.application.view.MultiViewHandler.renderView(MultiViewHandler.java:194)
    at javax.faces.application.ViewHandlerWrapper.renderView(ViewHandlerWrapper.java:151)
    at javax.faces.application.ViewHandlerWrapper.renderView(ViewHandlerWrapper.java:151)
    at org.omnifaces.viewhandler.OmniViewHandler.renderView(OmniViewHandler.java:155)
    at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:126)
    at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:100)
    at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:223)
    at javax.faces.webapp.FacesServlet.service(FacesServlet.java:671)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at ar.com.dux.jsf.filters.CacheFilter.doFilter(CacheFilter.java:27)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at ar.com.dux.jsf.filters.SecurityFilter.doFilter(SecurityFilter.java:84)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.primefaces.webapp.filter.FileUploadFilter.doFilter(FileUploadFilter.java:89)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.omnifaces.filter.GzipResponseFilter.doFilter(GzipResponseFilter.java:183)
    at org.omnifaces.filter.HttpFilter.doFilter(HttpFilter.java:108)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:196)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:97)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:542)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:135)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81)
    at org.apache.catalina.valves.AbstractAccessLogValve.invoke(AbstractAccessLogValve.java:698)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:78)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:364)
    at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:624)
    at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
    at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:831)
    at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1650)
    at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
    at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1191)
    at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659)
    at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
    at java.lang.Thread.run(Thread.java:748)

我们使用 JSF 2.3.9、Primefaces 8.0、Omnifaces 3.11、Tomcat 8 并且 bean 是 ViewScoped（javax.faces.view.ViewScoped 不是 omnifaces）。

该页面非常复杂，但他的基本功能是生成发票，因此我们有一个用于客户数据的部分，另一个用于添加到发票的产品部分和另一个用于付款信息的部分（使用 facelets 包括）。最后两个部分具有排序的数据表，并从所有其他部分更新。

Answer 1

该问题有两个可能的原因：

多个线程在同一个列表上工作

• 在迭代列表时修改列表的单个线程（例如 counted for 或 foreach）
• 第二个选项不应该是这里的原因，因为堆栈跟踪只包含对ArrayList.sort的调用。 我不认为 JDK 在那个地方有问题。

第一个选项更有可能：

同时的 AJAX 请求

• com.sun.faces.context.PartialViewContextImpl.processPartial应该是一个指示，这发生在 AJAX 共享列表期间由于错误的 bean 范围 - 例如会话甚至应用程序正确的 bean 范围，但列表来自共享源

您可以尝试 2 种解决方案中的 1 种...

• 包装你的支持 bean 列表Collections.synchronizedList.... List<Object> objList = Collections.synchronizedList(new ArrayList<Object>());
• 尝试java.util.concurrent.CopyOnWriteArrayList https://docs.oracle.com/en/java/javase/11/docs/api/java.base/java/util/concurrent/CopyOnWriteArrayList.html修改成本很高，但请稍等- 免费阅读。