在JSF saveState（）期间，线程在HashMap中停留在100％CPU使用率

Question

我们的生产环境中存在问题，HTOP命令中的4个线程的CPU使用率为100％。为了进一步研究该问题，我生成了一个线程转储，以查找正在占用CPU的线程。

这是我发现的。这4个线程具有相同的堆栈跟踪，所有堆栈跟踪均处于 RUNNABLE
状态。不幸的是，由于堆栈跟踪没有引用我的内部代码，所以我一直停留在调查中，而更多地是在Richfaces方面。我认为这是JSF呈现页面的部分。

堆栈跟踪。

"ajp-0.0.0.0-8009-47" daemon prio=10 tid=0x00007fb8040af000 nid=0x172c runnable [0x00007fb8b3bf8000]
   java.lang.Thread.State: RUNNABLE
    at java.util.HashMap.hash(HashMap.java:351)
    at java.util.HashMap.putForCreate(HashMap.java:512)
    at java.util.HashMap.putAllForCreate(HashMap.java:534)
    at java.util.HashMap.<init>(HashMap.java:320)
    at org.ajax4jsf.component.UIDataAdaptorBase.createChildStateCopy(UIDataAdaptorBase.java:894)
    at org.ajax4jsf.component.UIDataAdaptorBase.saveState(UIDataAdaptorBase.java:1554)
    at org.richfaces.component.UIDataTable.saveState(UIDataTable.java:181)
    at org.richfaces.component.html.HtmlDataTable.saveState(HtmlDataTable.java:1361)
    at javax.faces.component.UIComponentBase.processSaveState(UIComponentBase.java:1103)
    at javax.faces.component.UIComponentBase.processSaveState(UIComponentBase.java:1119)
    at javax.faces.component.UIComponentBase.processSaveState(UIComponentBase.java:1119)
    at javax.faces.component.UIComponentBase.processSaveState(UIComponentBase.java:1119)
    at javax.faces.component.UIComponentBase.processSaveState(UIComponentBase.java:1119)
    at javax.faces.component.UIComponentBase.processSaveState(UIComponentBase.java:1119)
    at javax.faces.component.UIComponentBase.processSaveState(UIComponentBase.java:1119)
    at javax.faces.component.UIComponentBase.processSaveState(UIComponentBase.java:1119)
    at org.ajax4jsf.component.AjaxViewRoot.processSaveState(AjaxViewRoot.java:751)
    at org.ajax4jsf.application.AjaxStateManager.getComponentStateToSave(AjaxStateManager.java:179)
    at org.ajax4jsf.application.AjaxStateManager.buildViewState(AjaxStateManager.java:515)
    at org.ajax4jsf.application.AjaxStateManager$SeamStateManagerWrapper.saveView(AjaxStateManager.java:106)
    at org.jboss.seam.jsf.SeamStateManager.saveView(SeamStateManager.java:89)
    at org.ajax4jsf.application.AjaxStateManager.saveSerializedView(AjaxStateManager.java:470)
    at com.sun.facelets.FaceletViewHandler.renderView(FaceletViewHandler.java:615)
    at org.ajax4jsf.application.ViewHandlerWrapper.renderView(ViewHandlerWrapper.java:100)
    at org.ajax4jsf.application.AjaxViewHandler.renderView(AjaxViewHandler.java:176)
    at com.sun.faces.lifecycle.RenderResponsePhase.execute(RenderResponsePhase.java:110)
    at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:100)
    at com.sun.faces.lifecycle.LifecycleImpl.render(LifecycleImpl.java:139)
    at javax.faces.webapp.FacesServlet.service(FacesServlet.java:266)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.josso.servlet.agent.GenericServletSSOAgentFilter.doFilter(GenericServletSSOAgentFilter.java:558)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:83)
    at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:73)
    at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:73)
    at org.jboss.seam.web.IdentityFilter.doFilter(IdentityFilter.java:40)
    at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
    at org.jboss.seam.web.MultipartFilter.doFilter(MultipartFilter.java:90)
    at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
    at org.jboss.seam.web.ExceptionFilter.doFilter(ExceptionFilter.java:64)
    at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
    at org.jboss.seam.web.RedirectFilter.doFilter(RedirectFilter.java:45)
    at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
    at org.ajax4jsf.webapp.BaseXMLFilter.doXmlFilter(BaseXMLFilter.java:206)
    at org.ajax4jsf.webapp.BaseFilter.handleRequest(BaseFilter.java:290)
    at org.ajax4jsf.webapp.BaseFilter.processUploadsAndHandleRequest(BaseFilter.java:388)
    at org.ajax4jsf.webapp.BaseFilter.doFilter(BaseFilter.java:515)
    at org.jboss.seam.web.Ajax4jsfFilter.doFilter(Ajax4jsfFilter.java:56)
    at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
    at org.jboss.seam.web.LoggingFilter.doFilter(LoggingFilter.java:60)
    at org.jboss.seam.servlet.SeamFilter$FilterChainImpl.doFilter(SeamFilter.java:69)
    at org.jboss.seam.servlet.SeamFilter.doFilter(SeamFilter.java:158)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:235)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:235)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
    at org.jboss.web.tomcat.security.SecurityAssociationValve.invoke(SecurityAssociationValve.java:190)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:433)
    at org.jboss.web.tomcat.security.JaccContextValve.invoke(JaccContextValve.java:92)
    at org.jboss.web.tomcat.security.SecurityContextEstablishmentValve.process(SecurityContextEstablishmentValve.java:126)
    at org.jboss.web.tomcat.security.SecurityContextEstablishmentValve.invoke(SecurityContextEstablishmentValve.java:70)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
    at org.jboss.web.tomcat.service.jca.CachedConnectionValve.invoke(CachedConnectionValve.java:158)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:330)
    at org.apache.coyote.ajp.AjpProcessor.process(AjpProcessor.java:436)
    at org.apache.coyote.ajp.AjpProtocol$AjpConnectionHandler.process(AjpProtocol.java:384)
    at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
    at java.lang.Thread.run(Thread.java:722)

另一件事是，我有什么方法可以利用堆栈跟踪，可以说我想生成一个日志，以便我可以知道正在生成该堆栈跟踪的应用程序中的哪个页面？或者，也许我可以使用相位监听器？

任何帮助，将不胜感激。谢谢。

我正在使用Seam 2.2，Richfaces 3.3.3 final，JSF 1.2。

Answer 1

这个，

java.lang.Thread.State: RUNNABLE
    at java.util.HashMap.hash(HashMap.java:351)
    at java.util.HashMap.putForCreate(HashMap.java:512)
    at java.util.HashMap.putAllForCreate(HashMap.java:534)
    at java.util.HashMap.<init>(HashMap.java:320)

还有这个，

java.lang.Thread.State: RUNNABLE
    at java.util.HashMap.getEntry(HashMap.java:446)
    at java.util.HashMap.get(HashMap.java:405)

是已知的线程安全问题，java.util.HashMap其中一个线程get()同时调用另一个线程同时调用a
put()。线程将在计算哈希值时陷入无限循环。解决此问题的技术方法是改用ConcurrentMap实现。另请参见此dzone文章。

但是，根据您的具体情况，

    at java.util.HashMap.<init>(HashMap.java:320)
    at org.ajax4jsf.component.UIDataAdaptorBase.createChildStateCopy(UIDataAdaptorBase.java:894)
    at org.ajax4jsf.component.UIDataAdaptorBase.saveState(UIDataAdaptorBase.java:1554)
    at org.richfaces.component.UIDataTable.saveState(UIDataTable.java:181)
    at org.richfaces.component.html.HtmlDataTable.saveState(HtmlDataTable.java:1361)
    at javax.faces.component.UIComponentBase.processSaveState(UIComponentBase.java:1103)

当您<rich:dataTable>要保存组件的状态时，此问题似乎很明显。这又表明该组件的同一实例正在由多个线程访问。这是不对的，UIComponent该类从一开始就从来没有被设计为线程安全的。这反过来表明所讨论的组件实例未按JSF规范的要求进行作用域限定。例如，当您binding用于将组件绑定到会话作用域或什至是应用程序作用域的bean或更糟糕的是静态字段时，可能会发生这种情况。

<x:someComponent ... binding="#{nonRequestScopedBean.someComponent}">

您应该在代码库中查找这样的组件，并通过确保bean是请求范围的，或通过对需求/问题使用不同的解决方案（您认为使用binding此方法是正确的解决方案）来进行相应的修复。