1.背景
同社の監視ツールを監視したところ、社内のアプリケーションのCPU使用率が120％に達していることがわかりました。つまり、このアプリケーションは1つのCPUを占有しているのですが、なぜそんなに高いのでしょうか。一緒にチェックしましょう
2.調査を開始します
（1）最初のステップは、CPUが高すぎるアプリケーションのプロセス情報を取得することです（トップコマンドモニタリング）
（2）プロセスを通じてCPUが高すぎるスレッドを取得します（Top -H -p <pid>）。
（3）jstackコマンドを使用してスレッドのスタック情報をエクスポートします
"http-bio-7051-exec-28" #33168 daemon prio=5 os_prio=0 tid=0x00007fe343f77000 nid=0xaa1 runnable [0x00007fe329287000]
java.lang.Thread.State: RUNNABLE
at java.lang.StringBuilder.append(StringBuilder.java:214)
at sun.util.calendar.CalendarUtils.sprintf0d(CalendarUtils.java:171)
at java.util.Date.toString(Date.java:1040)
at java.lang.String.valueOf(String.java:2994)
at java.lang.StringBuilder.append(StringBuilder.java:131)
at com.jiuyescm.oms.wm.odo.action.service.impl.CommonOmsOrderSendAction.buildAppointKey(CommonOmsOrderSendAction.java:72)
at com.jiuyescm.oms.wm.odo.controller.OmsDo2BController.queryStorage(OmsDo2BController.java:1007)
at sun.reflect.GeneratedMethodAccessor2011.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at com.bstek.dorado.data.method.MethodAutoMatchingUtils.invokeMethod(MethodAutoMatchingUtils.java:602)
at com.bstek.dorado.data.method.MethodAutoMatchingUtils.invokeMethod(MethodAutoMatchingUtils.java:695)
at com.bstek.dorado.data.provider.manager.DataProviderInterceptorInvoker.invokeInterceptorByParamType(DataProviderInterceptorInvoker.java:542)
at com.bstek.dorado.data.provider.manager.DataProviderInterceptorInvoker.invoke(DataProviderInterceptorInvoker.java:157)
at com.bstek.dorado.util.proxy.ChainedMethodInvocation.proceed(ChainedMethodInvocation.java:73)
at com.bstek.dorado.data.provider.DataProviderGetResultMethodInterceptor.invokeGetResult(DataProviderGetResultMethodInterceptor.java:29)
at com.bstek.dorado.data.provider.AbstractDataProviderGetResultMethodInterceptor.invoke(AbstractDataProviderGetResultMethodInterceptor.java:55)
at com.bstek.dorado.util.proxy.MethodInterceptorDispatcher.invoke(MethodInterceptorDispatcher.java:241)
at com.bstek.dorado.data.provider.DirectDataProvider_$$_jvst349_17.getResult(DirectDataProvider_$$_jvst349_17.java)
at com.bstek.dorado.view.service.LoadDataServiceProcessor.doExecute(LoadDataServiceProcessor.java:258)
at com.bstek.dorado.view.service.DataServiceProcessorSupport.execute(DataServiceProcessorSupport.java:133)
at com.bstek.dorado.view.resolver.ViewServiceInvoker.invoke(ViewServiceInvoker.java:32)
at com.bstek.dorado.view.resolver.ViewServiceInvoker_$$_jvst349_16._d5invoke(ViewServiceInvoker_$$_jvst349_16.java)
at sun.reflect.GeneratedMethodAccessor216.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at com.bstek.dorado.util.proxy.MethodInterceptorDispatcher$FinalJavassistMethodInterceptor.invoke(MethodInterceptorDispatcher.java:96)
at com.bstek.dorado.util.proxy.ChainedMethodInvocation.proceed(ChainedMethodInvocation.java:73)
at com.bstek.dorado.util.proxy.MethodInterceptorDispatcher$FinalAopallianceMethodInterceptor.invoke(MethodInterceptorDispatcher.java:67)
at com.bstek.dorado.util.proxy.ChainedMethodInvocation.proceed(ChainedMethodInvocation.java:73)
at com.jiuyescm.cfm.dorado.interceptor.SessionValidationRemoteServiceMethodInterceptor.invoke(SessionValidationRemoteServiceMethodInterceptor.java:33)
at com.bstek.dorado.view.service.AbstractRemoteServiceMethodInterceptor.invoke(AbstractRemoteServiceMethodInterceptor.java:30)
at com.bstek.dorado.util.proxy.ChainedMethodInvocation.proceed(ChainedMethodInvocation.java:73)
at com.bstek.bdf2.core.exception.interceptor.AjaxMethodInterceptor.invoke(AjaxMethodInterceptor.java:26)
at com.bstek.dorado.util.proxy.MethodInterceptorDispatcher.invoke(MethodInterceptorDispatcher.java:170)
at com.bstek.dorado.util.proxy.MethodInterceptorDispatcher.invoke(MethodInterceptorDispatcher.java:241)
at com.bstek.dorado.view.resolver.ViewServiceInvoker_$$_jvst349_16.invoke(ViewServiceInvoker_$$_jvst349_16.java)
at com.bstek.dorado.view.resolver.ViewServiceResolver.processTask(ViewServiceResolver.java:154)
at com.bstek.dorado.view.resolver.ViewServiceResolver.execute(ViewServiceResolver.java:244)
at com.bstek.dorado.web.resolver.AbstractTextualResolver.doHandleRequest(AbstractTextualResolver.java:128)
at com.bstek.dorado.web.resolver.WebContextSupportedController.handleRequestInternal(WebContextSupportedController.java:70)
at org.springframework.web.servlet.mvc.AbstractController.handleRequest(AbstractController.java:154)
at org.springframework.web.servlet.mvc.SimpleControllerHandlerAdapter.handle(SimpleControllerHandlerAdapter.java:50)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:945)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:876)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:931)
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:833)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:650)
at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:807)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:731)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at com.alibaba.druid.support.http.WebStatFilter.doFilter(WebStatFilter.java:123)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:108)
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:84)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:118)
at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:84)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:113)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at com.bstek.bdf2.core.security.filter.ControllerFilter.doFilter(ControllerFilter.java:64)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:103)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:113)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.authentication.rememberme.RememberMeAuthenticationFilter.doFilter(RememberMeAuthenticationFilter.java:146)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:54)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:45)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.authentication.www.BasicAuthenticationFilter.doFilter(BasicAuthenticationFilter.java:150)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:183)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:183)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.jasig.cas.client.session.SingleSignOutFilter.doFilter(SingleSignOutFilter.java:100)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at com.bstek.bdf2.core.security.filter.PreAuthenticatedProcessingFilter.doFilter(PreAuthenticatedProcessingFilter.java:41)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:105)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.session.ConcurrentSessionFilter.doFilter(ConcurrentSessionFilter.java:125)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at com.bstek.bdf2.core.security.filter.ContextFilter.doFilter(ContextFilter.java:36)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:87)
at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:192)
at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:160)
at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:344)
at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:261)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:88)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:108)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:219)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:110)
at com.r.tomcat.session.management.RequestSessionHandlerValve.invoke(RequestSessionHandlerValve.java:30)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:169)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103)
at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:962)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:445)
at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1115)
at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:637)
at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:316)
- locked <0x0000000724439528> (a org.apache.tomcat.util.net.SocketWrapper)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.lang.Thread.run(Thread.java:748)上記のログから犯人を見つけてください
at java.lang.StringBuilder.append(StringBuilder.java:214)
at sun.util.calendar.CalendarUtils.sprintf0d(CalendarUtils.java:171)
at java.util.Date.toString(Date.java:1040)
at java.lang.String.valueOf(String.java:2994)
at java.lang.StringBuilder.append(StringBuilder.java:131)
at com.jiuyescm.oms.wm.odo.action.service.impl.CommonOmsOrderSendAction.buildAppointKey(CommonOmsOrderSendAction.java:72)
at com.jiuyescm.oms.wm.odo.controller.OmsDo2BController.queryStorage(OmsDo2BController.java:1007)（4）コードを組み合わせて真実を見つける
3.まとめ
私たちのスタックに対応して、エネルギー消費のコストはここでループ呼び出し文字列に接続されています。ここでは、演算子「+」を使用した文字列スプライシングの問題について説明します。「+」を使用して固定長の文字列を接続すると、パフォーマンスに問題が発生しますが、ループで「+」を使用すると、文字列を使用すると、パフォーマンスが指数関数的に低下します。文字列があると仮定して、この文字列に対して多くのループスプライシング操作を実行します。「+」を使用すると、パフォーマンスが最低になります。インターネット上には比較記事がたくさんあり、たくさん探します。私を信じていない場合は、デモを書いて1000回呼び出してから、自分のCPUの状況を確認してください。