java - 在 JSF saveState() 期间，HashMap 中的线程停留在 100% 的 CPU 使用率

Question

我们在生产环境中遇到问题，HTOP 命令导致 4 个线程的 CPU 使用率达到 100%。为了进一步调查这个问题，我生成了一个线程转储，以找出哪个线程正在占用 CPU。

这是我发现的。 4 个线程具有相同的堆栈跟踪，所有这些都处于 RUNNABLE 状态。不幸的是，我被困在我的调查中，因为堆栈跟踪没有引用我的内部代码，它更多地在 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，假设我想生成一个日志，这样我就可以知道在我的应用程序中的哪个页面生成了这个堆栈跟踪？或者也许我可以使用相位监听器？

如有任何帮助，我们将不胜感激。 谢谢。

我使用的是 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)

java.util.HashMap 是已知的线程安全问题当一个线程调用 get()而另一个线程同时执行 put() .该线程将在计算散列期间陷入无限循环。此问题的技术解决方案是使用 ConcurrentMap实现代替。另见 a.o. this dzone article .

但是，在您的具体情况下，

    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)

当您的 <rich:dataTable> 状态出现时，此问题就会出现。组件即将被保存。这反过来表明组件的同一个实例正在被多个线程访问。这不对，UIComponent类首先从未设计为线程安全的。这反过来表明所讨论的组件实例不是 JSF 规范所要求的请求范围。例如，当您使用 binding 时可能会发生这种情况将组件绑定(bind)到 session 范围或什至应用程序范围的 bean，或者更糟的是静态字段。

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

您应该在您的代码库中寻找这样的组件并相应地修复它，方法是确保该 bean 在请求范围内，或者针对您认为使用 binding 的需求/问题使用不同的解决方案。这种方式将是正确的解决方案。

另见:

• How does the 'binding' attribute work in JSF? When and how should it be used?