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實(shí)戰(zhàn)！用 Arthas 定位 Spring Boot 接口的超時(shí)問題，讓應(yīng)用起飛

作者：技術(shù)老男孩
開發(fā)
Arthas 是Alibaba開源的Java診斷工具，深受開發(fā)者喜愛，我只需要用他的一個(gè)小功能trace，動(dòng)態(tài)計(jì)算方法調(diào)用路徑和時(shí)間，這樣我就可以定位時(shí)間在哪個(gè)地方被消耗了。

一、背景

公司有個(gè)渠道系統(tǒng)，專門對(duì)接三方渠道使用，沒有什么業(yè)務(wù)邏輯，主要是轉(zhuǎn)換報(bào)文和參數(shù)校驗(yàn)之類的工作，起著一個(gè)承上啟下的作用。

最近在優(yōu)化接口的響應(yīng)時(shí)間，優(yōu)化了代碼之后，但是時(shí)間還是達(dá)不到要求；有一個(gè)詭異的100ms左右的耗時(shí)問題，在接口中打印了請(qǐng)求處理時(shí)間后，和調(diào)用方的響應(yīng)時(shí)間還有差了100ms左右。比如程序里記錄150ms，但是調(diào)用方等待時(shí)間卻為250ms左右。

下面記錄下當(dāng)時(shí)詳細(xì)的定位&解決流程（其實(shí)解決很簡(jiǎn)單，關(guān)鍵在于怎么定位并找到解決問題的方法）。

二、定位過程

1.分析代碼

渠道系統(tǒng)是一個(gè)常見的spring-boot web工程，使用了集成的tomcat。分析了代碼之后，發(fā)現(xiàn)并沒有特殊的地方，沒有特殊的過濾器或者攔截器，所以初步排除是業(yè)務(wù)代碼問題。

2.分析調(diào)用流程

出現(xiàn)這個(gè)問題之后，首先確認(rèn)了下接口的調(diào)用流程。由于是內(nèi)部測(cè)試，所以調(diào)用流程較少。

Nginx -反向代理-> 渠道系統(tǒng)

公司是云服務(wù)器，網(wǎng)絡(luò)走的也是云的內(nèi)網(wǎng)。由于不明確問題的原因，所以用排除法，首先確認(rèn)服務(wù)器網(wǎng)絡(luò)是否有問題。

先確認(rèn)發(fā)送端到Nginx Host是否有問題：

[jboss@VM_0_139_centos ~]$ ping 10.0.0.139  
PING 10.0.0.139 (10.0.0.139) 56(84) bytes of data.  
64 bytes from 10.0.0.139: icmp_seq=1 ttl=64 time=0.029 ms  
64 bytes from 10.0.0.139: icmp_seq=2 ttl=64 time=0.041 ms  
64 bytes from 10.0.0.139: icmp_seq=3 ttl=64 time=0.040 ms  
64 bytes from 10.0.0.139: icmp_seq=4 ttl=64 time=0.040 ms

從ping結(jié)果上看，發(fā)送端到Nginx主機(jī)的延遲是無問題的，接下來查看Nginx到渠道系統(tǒng)的網(wǎng)絡(luò)。

# 由于日志是沒問題的，這里直接復(fù)制上面日志了  
[jboss@VM_0_139_centos ~]$ ping 10.0.0.139  
PING 10.0.0.139 (10.0.0.139) 56(84) bytes of data.  
64 bytes from 10.0.0.139: icmp_seq=1 ttl=64 time=0.029 ms  
64 bytes from 10.0.0.139: icmp_seq=2 ttl=64 time=0.041 ms  
64 bytes from 10.0.0.139: icmp_seq=3 ttl=64 time=0.040 ms  
64 bytes from 10.0.0.139: icmp_seq=4 ttl=64 time=0.040 ms

從ping結(jié)果上看，Nginx到渠道系統(tǒng)服務(wù)器網(wǎng)絡(luò)延遲也是沒問題的。

既然網(wǎng)絡(luò)看似沒問題，那么可以繼續(xù)排除法，砍掉Nginx，客戶端直接再渠道系統(tǒng)的服務(wù)器上，通過回環(huán)地址（localhost）直連，避免經(jīng)過網(wǎng)卡/dns，縮小問題范圍看看能否復(fù)現(xiàn)（這個(gè)應(yīng)用和地址是我后期模擬的，測(cè)試的是一個(gè)空接口）：

[jboss@VM_10_91_centos tmp]$ curl -w "@curl-time.txt" http://127.0.0.1:7744/send  
success  
              http: 200  
               dns: 0.001s  
          redirect: 0.000s  
      time_connect: 0.001s  
   time_appconnect: 0.000s  
  time_pretransfer: 0.001s  
time_starttransfer: 0.073s  
     size_download: 7bytes  
    speed_download: 95.000B/s  
                  ----------  
        time_total: 0.073s 請(qǐng)求總耗時(shí)

從curl日志上看，通過回環(huán)地址調(diào)用一個(gè)空接口耗時(shí)也有73ms。這就奇怪了，跳過了中間所有調(diào)用節(jié)點(diǎn)（包括過濾器&攔截器之類），直接請(qǐng)求應(yīng)用一個(gè)空接口，都有73ms的耗時(shí)，再請(qǐng)求一次看看：

[jboss@VM_10_91_centos tmp]$ curl -w "@curl-time.txt" http://127.0.0.1:7744/send  
success  
              http: 200  
               dns: 0.001s  
          redirect: 0.000s  
      time_connect: 0.001s  
   time_appconnect: 0.000s  
  time_pretransfer: 0.001s  
time_starttransfer: 0.003s  
     size_download: 7bytes  
    speed_download: 2611.000B/s  
                  ----------  
        time_total: 0.003s

更奇怪的是，第二次請(qǐng)求耗時(shí)就正常了，變成了3ms。經(jīng)查閱資料，linux curl是默認(rèn)開啟http keep-alive的。就算不開啟keep-alive，每次重新handshake，也不至于需要70ms。

經(jīng)過不斷分析測(cè)試發(fā)現(xiàn)，連續(xù)請(qǐng)求的話時(shí)間就會(huì)很短，每次請(qǐng)求只需要幾毫秒，但是如果隔一段時(shí)間再請(qǐng)求，就會(huì)花費(fèi)70ms以上。

從這個(gè)現(xiàn)象猜想，可能是某些緩存機(jī)制導(dǎo)致的，連續(xù)請(qǐng)求因?yàn)橛芯彺妫运俣瓤?，時(shí)間長(zhǎng)緩存失效后導(dǎo)致時(shí)間長(zhǎng)。

那么這個(gè)問題點(diǎn)到底在哪一層呢？tomcat層還是spring-webmvc呢？

光猜想定位不了問題，還是得實(shí)際測(cè)試一下，把渠道系統(tǒng)的代碼放到本地ide里啟動(dòng)測(cè)試能否復(fù)現(xiàn)

但是導(dǎo)入本地Ide后，在Ide中啟動(dòng)后并不能復(fù)現(xiàn)問題，并沒有70+ms的延遲問題。這下頭疼了，本地?zé)o法復(fù)現(xiàn)，不能Debug，由于問題點(diǎn)不在業(yè)務(wù)代碼，也不能通過加日志的方式來Debug

這時(shí)候可以祭出神器Arthas了。

三、Arthas分析問題

Arthas 是Alibaba開源的Java診斷工具，深受開發(fā)者喜愛。當(dāng)你遇到以下類似問題而束手無策時(shí)，Arthas可以幫助你解決：

  • 這個(gè)類從哪個(gè) jar 包加載的？為什么會(huì)報(bào)各種類相關(guān)的 Exception？
  • 我改的代碼為什么沒有執(zhí)行到？難道是我沒 commit？分支搞錯(cuò)了？
  • 遇到問題無法在線上 debug，難道只能通過加日志再重新發(fā)布嗎？
  • 線上遇到某個(gè)用戶的數(shù)據(jù)處理有問題，但線上同樣無法 debug，線下無法重現(xiàn)！
  • 是否有一個(gè)全局視角來查看系統(tǒng)的運(yùn)行狀況？
  • 有什么辦法可以監(jiān)控到JVM的實(shí)時(shí)運(yùn)行狀態(tài)？

上面是Arthas的官方簡(jiǎn)介，這次我只需要用他的一個(gè)小功能trace。動(dòng)態(tài)計(jì)算方法調(diào)用路徑和時(shí)間，這樣我就可以定位時(shí)間在哪個(gè)地方被消耗了。

  • trace 方法內(nèi)部調(diào)用路徑，并輸出方法路徑上的每個(gè)節(jié)點(diǎn)上耗時(shí)
  • trace 命令能主動(dòng)搜索 class-pattern／method-pattern
  • 對(duì)應(yīng)的方法調(diào)用路徑，渲染和統(tǒng)計(jì)整個(gè)調(diào)用鏈路上的所有性能開銷和追蹤調(diào)用鏈路。

有了神器，那么該追蹤什么方法呢？由于我對(duì)Tomcat源碼不是很熟，所以只能從spring mvc下手，先來trace一下spring mvc的入口：

[arthas@24851]$ trace org.springframework.web.servlet.DispatcherServlet *  
Press Q or Ctrl+C to abort.  
Affect(class-cnt:1 , method-cnt:44) cost in 508 ms.  
`---ts=2019-09-14 21:07:44;thread_name=http-nio-7744-exec-2;id=11;is_daemon=true;priority=5;TCCL=org.springframework.boot.web.embedded.tomcat.TomcatEmbeddedWebappClassLoader@7c136917  
    `---[2.952142ms] org.springframework.web.servlet.DispatcherServlet:buildLocaleContext()  
  
`---ts=2019-09-14 21:07:44;thread_name=http-nio-7744-exec-2;id=11;is_daemon=true;priority=5;TCCL=org.springframework.boot.web.embedded.tomcat.TomcatEmbeddedWebappClassLoader@7c136917  
    `---[18.08903ms] org.springframework.web.servlet.DispatcherServlet:doService()  
        +---[0.041346ms] org.apache.commons.logging.Log:isDebugEnabled() #889  
        +---[0.022398ms] org.springframework.web.util.WebUtils:isIncludeRequest() #898  
        +---[0.014904ms] org.springframework.web.servlet.DispatcherServlet:getWebApplicationContext() #910  
        +---[1.071879ms] javax.servlet.http.HttpServletRequest:setAttribute() #910  
        +---[0.020977ms] javax.servlet.http.HttpServletRequest:setAttribute() #911  
        +---[0.017073ms] javax.servlet.http.HttpServletRequest:setAttribute() #912  
        +---[0.218277ms] org.springframework.web.servlet.DispatcherServlet:getThemeSource() #913  
        |   `---[0.137568ms] org.springframework.web.servlet.DispatcherServlet:getThemeSource()  
        |       `---[min=0.00783ms,max=0.014251ms,total=0.022081ms,count=2] org.springframework.web.servlet.DispatcherServlet:getWebApplicationContext() #782  
        +---[0.019363ms] javax.servlet.http.HttpServletRequest:setAttribute() #913  
        +---[0.070694ms] org.springframework.web.servlet.FlashMapManager:retrieveAndUpdate() #916  
        +---[0.01839ms] org.springframework.web.servlet.FlashMap:<init>() #920  
        +---[0.016943ms] javax.servlet.http.HttpServletRequest:setAttribute() #920  
        +---[0.015268ms] javax.servlet.http.HttpServletRequest:setAttribute() #921  
        +---[15.050124ms] org.springframework.web.servlet.DispatcherServlet:doDispatch() #925  
        |   `---[14.943477ms] org.springframework.web.servlet.DispatcherServlet:doDispatch()  
        |       +---[0.019135ms] org.springframework.web.context.request.async.WebAsyncUtils:getAsyncManager() #953  
        |       +---[2.108373ms] org.springframework.web.servlet.DispatcherServlet:checkMultipart() #960  
        |       |   `---[2.004436ms] org.springframework.web.servlet.DispatcherServlet:checkMultipart()  
        |       |       `---[1.890845ms] org.springframework.web.multipart.MultipartResolver:isMultipart() #1117  
        |       +---[2.054361ms] org.springframework.web.servlet.DispatcherServlet:getHandler() #964  
        |       |   `---[1.961963ms] org.springframework.web.servlet.DispatcherServlet:getHandler()  
        |       |       +---[0.02051ms] java.util.List:iterator() #1183  
        |       |       +---[min=0.003805ms,max=0.009641ms,total=0.013446ms,count=2] java.util.Iterator:hasNext() #1183  
        |       |       +---[min=0.003181ms,max=0.009751ms,total=0.012932ms,count=2] java.util.Iterator:next() #1183  
        |       |       +---[min=0.005841ms,max=0.015308ms,total=0.021149ms,count=2] org.apache.commons.logging.Log:isTraceEnabled() #1184  
        |       |       `---[min=0.474739ms,max=1.19145ms,total=1.666189ms,count=2] org.springframework.web.servlet.HandlerMapping:getHandler() #1188  
        |       +---[0.013071ms] org.springframework.web.servlet.HandlerExecutionChain:getHandler() #971  
        |       +---[0.372236ms] org.springframework.web.servlet.DispatcherServlet:getHandlerAdapter() #971  
        |       |   `---[0.280073ms] org.springframework.web.servlet.DispatcherServlet:getHandlerAdapter()  
        |       |       +---[0.004804ms] java.util.List:iterator() #1224  
        |       |       +---[0.003668ms] java.util.Iterator:hasNext() #1224  
        |       |       +---[0.003038ms] java.util.Iterator:next() #1224  
        |       |       +---[0.006451ms] org.apache.commons.logging.Log:isTraceEnabled() #1225  
        |       |       `---[0.012683ms] org.springframework.web.servlet.HandlerAdapter:supports() #1228  
        |       +---[0.012848ms] javax.servlet.http.HttpServletRequest:getMethod() #974  
        |       +---[0.013132ms] java.lang.String:equals() #975  
        |       +---[0.003025ms] org.springframework.web.servlet.HandlerExecutionChain:getHandler() #977  
        |       +---[0.008095ms] org.springframework.web.servlet.HandlerAdapter:getLastModified() #977  
        |       +---[0.006596ms] org.apache.commons.logging.Log:isDebugEnabled() #978  
        |       +---[0.018024ms] org.springframework.web.context.request.ServletWebRequest:<init>() #981  
        |       +---[0.017869ms] org.springframework.web.context.request.ServletWebRequest:checkNotModified() #981  
        |       +---[0.038542ms] org.springframework.web.servlet.HandlerExecutionChain:applyPreHandle() #986  
        |       +---[0.00431ms] org.springframework.web.servlet.HandlerExecutionChain:getHandler() #991  
        |       +---[4.248493ms] org.springframework.web.servlet.HandlerAdapter:handle() #991  
        |       +---[0.014805ms] org.springframework.web.context.request.async.WebAsyncManager:isConcurrentHandlingStarted() #993  
        |       +---[1.444994ms] org.springframework.web.servlet.DispatcherServlet:applyDefaultViewName() #997  
        |       |   `---[0.067631ms] org.springframework.web.servlet.DispatcherServlet:applyDefaultViewName()  
        |       +---[0.012027ms] org.springframework.web.servlet.HandlerExecutionChain:applyPostHandle() #998  
        |       +---[0.373997ms] org.springframework.web.servlet.DispatcherServlet:processDispatchResult() #1008  
        |       |   `---[0.197004ms] org.springframework.web.servlet.DispatcherServlet:processDispatchResult()  
        |       |       +---[0.007074ms] org.apache.commons.logging.Log:isDebugEnabled() #1075  
        |       |       +---[0.005467ms] org.springframework.web.context.request.async.WebAsyncUtils:getAsyncManager() #1081  
        |       |       +---[0.004054ms] org.springframework.web.context.request.async.WebAsyncManager:isConcurrentHandlingStarted() #1081  
        |       |       `---[0.011988ms] org.springframework.web.servlet.HandlerExecutionChain:triggerAfterCompletion() #1087  
        |       `---[0.004015ms] org.springframework.web.context.request.async.WebAsyncManager:isConcurrentHandlingStarted() #1018  
        +---[0.005055ms] org.springframework.web.context.request.async.WebAsyncUtils:getAsyncManager() #928  
        `---[0.003422ms] org.springframework.web.context.request.async.WebAsyncManager:isConcurrentHandlingStarted() #928  
[jboss@VM_10_91_centos tmp]$ curl -w "@curl-time.txt" http://127.0.0.1:7744/send  
success  
              http: 200  
               dns: 0.001s  
          redirect: 0.000s  
      time_connect: 0.001s  
   time_appconnect: 0.000s  
  time_pretransfer: 0.001s  
time_starttransfer: 0.115s  
     size_download: 7bytes  
    speed_download: 60.000B/s  
                  ----------  
        time_total: 0.115s

本次調(diào)用，調(diào)用端時(shí)間花費(fèi)115ms，但是從arthas trace上看，spring mvc只消耗了18ms，那么剩下的97ms去哪了呢？

本地測(cè)試后已經(jīng)可以排除spring mvc的問題了，最后也是唯一可能出問題的點(diǎn)就是tomcat

可是本人并不熟悉tomcat中的源碼，就連請(qǐng)求入口都不清楚，tomcat里需要trace的類都不好找。。。

不過沒關(guān)系，有神器Arthas，可以通過stack命令來反向查找調(diào)用路徑，以org.springframework.web.servlet.DispatcherServlet作為參數(shù)：

stack 輸出當(dāng)前方法被調(diào)用的調(diào)用路徑很多時(shí)候我們都知道一個(gè)方法被執(zhí)行，但這個(gè)方法被執(zhí)行的路徑非常多，或者你根本就不知道這個(gè)方法是從那里被執(zhí)行了，此時(shí)你需要的是 stack 命令。

[arthas@24851]$ stack org.springframework.web.servlet.DispatcherServlet *  
Press Q or Ctrl+C to abort.  
Affect(class-cnt:1 , method-cnt:44) cost in 495 ms.  
ts=2019-09-14 21:15:19;thread_name=http-nio-7744-exec-5;id=14;is_daemon=true;priority=5;TCCL=org.springframework.boot.web.embedded.tomcat.TomcatEmbeddedWebappClassLoader@7c136917  
    @org.springframework.web.servlet.FrameworkServlet.processRequest()  
        at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:866)  
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:635)  
        at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:851)  
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:742)  
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)  
        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.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99)  
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)  
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)  
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)  
        at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:109)  
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)  
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)  
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)  
        at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:81)  
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)  
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)  
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)  
        at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:200)  
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)  
        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:198)  
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)  
        at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:496)  
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140)  
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81)  
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)  
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342)  
        at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:803)  
        at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)  
        at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:790)  
        at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1468)  
        at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)  
        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)  
  
ts=2019-09-14 21:15:19;thread_name=http-nio-7744-exec-5;id=14;is_daemon=true;priority=5;TCCL=org.springframework.boot.web.embedded.tomcat.TomcatEmbeddedWebappClassLoader@7c136917  
    @org.springframework.web.servlet.DispatcherServlet.doService()  
        at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:974)  
        at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:866)  
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:635)  
        at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:851)  
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:742)  
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)  
        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.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99)  
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)  
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)  
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)  
        at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:109)  
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)  
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)  
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)  
        at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:81)  
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)  
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)  
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)  
        at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:200)  
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)  
        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:198)  
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)  
        at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:496)  
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:140)  
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:81)  
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:87)  
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:342)  
        at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:803)  
        at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:66)  
        at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:790)  
        at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1468)  
        at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)  
        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)

從stack日志上可以很直觀的看出DispatchServlet的調(diào)用棧，那么這么長(zhǎng)的路徑，該trace哪個(gè)類呢（這里跳過spring mvc中的過濾器的trace過程，實(shí)際排查的時(shí)候也trace了一遍，但這詭異的時(shí)間消耗不是由這里過濾器產(chǎn)生的）？

有一定經(jīng)驗(yàn)的老司機(jī)從名字上大概也能猜出來從哪里下手比較好，那就是org.apache.coyote.http11.Http11Processor.service，從名字上看，http1.1處理器，這可能是一個(gè)比較好的切入點(diǎn)。下面來trace一下：

[arthas@24851]$ trace org.apache.coyote.http11.Http11Processor service  
Press Q or Ctrl+C to abort.  
Affect(class-cnt:1 , method-cnt:1) cost in 269 ms.  
`---ts=2019-09-14 21:22:51;thread_name=http-nio-7744-exec-8;id=17;is_daemon=true;priority=5;TCCL=org.springframework.boot.loader.LaunchedURLClassLoader@20ad9418  
    `---[131.650285ms] org.apache.coyote.http11.Http11Processor:service()  
        +---[0.036851ms] org.apache.coyote.Request:getRequestProcessor() #667  
        +---[0.009986ms] org.apache.coyote.RequestInfo:setStage() #668  
        +---[0.008928ms] org.apache.coyote.http11.Http11Processor:setSocketWrapper() #671  
        +---[0.013236ms] org.apache.coyote.http11.Http11InputBuffer:init() #672  
        +---[0.00981ms] org.apache.coyote.http11.Http11OutputBuffer:init() #673  
        +---[min=0.00213ms,max=0.007317ms,total=0.009447ms,count=2] org.apache.coyote.http11.Http11Processor:getErrorState() #683  
        +---[min=0.002098ms,max=0.008888ms,total=0.010986ms,count=2] org.apache.coyote.ErrorState:isError() #683  
        +---[min=0.002448ms,max=0.007149ms,total=0.009597ms,count=2] org.apache.coyote.http11.Http11Processor:isAsync() #683  
        +---[min=0.002399ms,max=0.00852ms,total=0.010919ms,count=2] org.apache.tomcat.util.net.AbstractEndpoint:isPaused() #683  
        +---[min=0.033587ms,max=0.11832ms,total=0.151907ms,count=2] org.apache.coyote.http11.Http11InputBuffer:parseRequestLine() #687  
        +---[0.005384ms] org.apache.tomcat.util.net.AbstractEndpoint:isPaused() #695  
        +---[0.007924ms] org.apache.coyote.Request:getMimeHeaders() #702  
        +---[0.006744ms] org.apache.tomcat.util.net.AbstractEndpoint:getMaxHeaderCount() #702  
        +---[0.012574ms] org.apache.tomcat.util.http.MimeHeaders:setLimit() #702  
        +---[0.14319ms] org.apache.coyote.http11.Http11InputBuffer:parseHeaders() #703  
        +---[0.003997ms] org.apache.coyote.Request:getMimeHeaders() #743  
        +---[0.026561ms] org.apache.tomcat.util.http.MimeHeaders:values() #743  
        +---[min=0.002869ms,max=0.01203ms,total=0.014899ms,count=2] java.util.Enumeration:hasMoreElements() #745  
        +---[0.070114ms] java.util.Enumeration:nextElement() #746  
        +---[0.010921ms] java.lang.String:toLowerCase() #746  
        +---[0.008453ms] java.lang.String:contains() #746  
        +---[0.002698ms] org.apache.coyote.http11.Http11Processor:getErrorState() #775  
        +---[0.00307ms] org.apache.coyote.ErrorState:isError() #775  
        +---[0.002708ms] org.apache.coyote.RequestInfo:setStage() #777  
        +---[0.171139ms] org.apache.coyote.http11.Http11Processor:prepareRequest() #779  
        +---[0.009349ms] org.apache.tomcat.util.net.SocketWrapperBase:decrementKeepAlive() #794  
        +---[0.002574ms] org.apache.coyote.http11.Http11Processor:getErrorState() #800  
        +---[0.002696ms] org.apache.coyote.ErrorState:isError() #800  
        +---[0.002499ms] org.apache.coyote.RequestInfo:setStage() #802  
        +---[0.005641ms] org.apache.coyote.http11.Http11Processor:getAdapter() #803  
        +---[129.868916ms] org.apache.coyote.Adapter:service() #803  
        +---[0.003859ms] org.apache.coyote.http11.Http11Processor:getErrorState() #809  
        +---[0.002365ms] org.apache.coyote.ErrorState:isError() #809  
        +---[0.003844ms] org.apache.coyote.http11.Http11Processor:isAsync() #809  
        +---[0.002382ms] org.apache.coyote.Response:getStatus() #809  
        +---[0.002476ms] org.apache.coyote.http11.Http11Processor:statusDropsConnection() #809  
        +---[0.002284ms] org.apache.coyote.RequestInfo:setStage() #838  
        +---[0.00222ms] org.apache.coyote.http11.Http11Processor:isAsync() #839  
        +---[0.037873ms] org.apache.coyote.http11.Http11Processor:endRequest() #843  
        +---[0.002188ms] org.apache.coyote.RequestInfo:setStage() #845  
        +---[0.002112ms] org.apache.coyote.http11.Http11Processor:getErrorState() #849  
        +---[0.002063ms] org.apache.coyote.ErrorState:isError() #849  
        +---[0.002504ms] org.apache.coyote.http11.Http11Processor:isAsync() #853  
        +---[0.009808ms] org.apache.coyote.Request:updateCounters() #854  
        +---[0.002008ms] org.apache.coyote.http11.Http11Processor:getErrorState() #855  
        +---[0.002192ms] org.apache.coyote.ErrorState:isIoAllowed() #855  
        +---[0.01968ms] org.apache.coyote.http11.Http11InputBuffer:nextRequest() #856  
        +---[0.010065ms] org.apache.coyote.http11.Http11OutputBuffer:nextRequest() #857  
        +---[0.002576ms] org.apache.coyote.RequestInfo:setStage() #870  
        +---[0.016599ms] org.apache.coyote.http11.Http11Processor:processSendfile() #872  
        +---[0.008182ms] org.apache.coyote.http11.Http11InputBuffer:getParsingRequestLinePhase() #688  
        +---[0.0075ms] org.apache.coyote.http11.Http11Processor:handleIncompleteRequestLineRead() #690  
        +---[0.001979ms] org.apache.coyote.RequestInfo:setStage() #875  
        +---[0.001981ms] org.apache.coyote.http11.Http11Processor:getErrorState() #877  
        +---[0.001934ms] org.apache.coyote.ErrorState:isError() #877  
        +---[0.001995ms] org.apache.tomcat.util.net.AbstractEndpoint:isPaused() #877  
        +---[0.002403ms] org.apache.coyote.http11.Http11Processor:isAsync() #879  
        `---[0.006176ms] org.apache.coyote.http11.Http11Processor:isUpgrade() #881

日志里有一個(gè)129ms的耗時(shí)點(diǎn)（時(shí)間比沒開arthas的時(shí)候更長(zhǎng)是因?yàn)閍rthas本身帶來的性能消耗，所以生產(chǎn)環(huán)境小心使用），這個(gè)就是要找的問題點(diǎn)。

打問題點(diǎn)找到了，那怎么定位是什么導(dǎo)致的問題呢，又如何解決呢？

繼續(xù)trace吧，細(xì)化到具體的代碼塊或者內(nèi)容。trace由于性能考慮，不會(huì)展示所有的調(diào)用路徑，如果調(diào)用路徑過深，只有手動(dòng)深入trace，原則就是trace耗時(shí)長(zhǎng)的那個(gè)方法：

[arthas@24851]$ trace org.apache.coyote.Adapter service  
Press Q or Ctrl+C to abort.  
Affect(class-cnt:1 , method-cnt:1) cost in 608 ms.  
`---ts=2019-09-14 21:34:33;thread_name=http-nio-7744-exec-1;id=10;is_daemon=true;priority=5;TCCL=org.springframework.boot.loader.LaunchedURLClassLoader@20ad9418  
    `---[81.70999ms] org.apache.catalina.connector.CoyoteAdapter:service()  
        +---[0.032546ms] org.apache.coyote.Request:getNote() #302  
        +---[0.007148ms] org.apache.coyote.Response:getNote() #303  
        +---[0.007475ms] org.apache.catalina.connector.Connector:getXpoweredBy() #324  
        +---[0.00447ms] org.apache.coyote.Request:getRequestProcessor() #331  
        +---[0.007902ms] java.lang.ThreadLocal:get() #331  
        +---[0.006522ms] org.apache.coyote.RequestInfo:setWorkerThreadName() #331  
        +---[73.793798ms] org.apache.catalina.connector.CoyoteAdapter:postParseRequest() #336  
        +---[0.001536ms] org.apache.catalina.connector.Connector:getService() #339  
        +---[0.004469ms] org.apache.catalina.Service:getContainer() #339  
        +---[0.007074ms] org.apache.catalina.Engine:getPipeline() #339  
        +---[0.004334ms] org.apache.catalina.Pipeline:isAsyncSupported() #339  
        +---[0.002466ms] org.apache.catalina.connector.Request:setAsyncSupported() #339  
        +---[6.01E-4ms] org.apache.catalina.connector.Connector:getService() #342  
        +---[0.001859ms] org.apache.catalina.Service:getContainer() #342  
        +---[9.65E-4ms] org.apache.catalina.Engine:getPipeline() #342  
        +---[0.005231ms] org.apache.catalina.Pipeline:getFirst() #342  
        +---[7.239154ms] org.apache.catalina.Valve:invoke() #342  
        +---[0.006904ms] org.apache.catalina.connector.Request:isAsync() #345  
        +---[0.00509ms] org.apache.catalina.connector.Request:finishRequest() #372  
        +---[0.051461ms] org.apache.catalina.connector.Response:finishResponse() #373  
        +---[0.007244ms] java.util.concurrent.atomic.AtomicBoolean:<init>() #379  
        +---[0.007314ms] org.apache.coyote.Response:action() #380  
        +---[0.004518ms] org.apache.catalina.connector.Request:isAsyncCompleting() #382  
        +---[0.001072ms] org.apache.catalina.connector.Request:getContext() #394  
        +---[0.007166ms] java.lang.System:currentTimeMillis() #401  
        +---[0.004367ms] org.apache.coyote.Request:getStartTime() #401  
        +---[0.011483ms] org.apache.catalina.Context:logAccess() #401  
        +---[0.0014ms] org.apache.coyote.Request:getRequestProcessor() #406  
        +---[min=8.0E-4ms,max=9.22E-4ms,total=0.001722ms,count=2] java.lang.Integer:<init>() #406  
        +---[0.001082ms] java.lang.reflect.Method:invoke() #406  
        +---[0.001851ms] org.apache.coyote.RequestInfo:setWorkerThreadName() #406  
        +---[0.035805ms] org.apache.catalina.connector.Request:recycle() #410  
        `---[0.007849ms] org.apache.catalina.connector.Response:recycle() #411

一段無聊的手動(dòng)深入trace之后………………

[arthas@24851]$ trace org.apache.catalina.webresources.AbstractArchiveResourceSet getArchiveEntries  
Press Q or Ctrl+C to abort.  
Affect(class-cnt:4 , method-cnt:2) cost in 150 ms.  
`---ts=2019-09-14 21:36:26;thread_name=http-nio-7744-exec-3;id=12;is_daemon=true;priority=5;TCCL=org.springframework.boot.loader.LaunchedURLClassLoader@20ad9418  
    `---[75.743681ms] org.apache.catalina.webresources.JarWarResourceSet:getArchiveEntries()  
        +---[0.025731ms] java.util.HashMap:<init>() #106  
        +---[0.097729ms] org.apache.catalina.webresources.JarWarResourceSet:openJarFile() #109  
        +---[0.091037ms] java.util.jar.JarFile:getJarEntry() #110  
        +---[0.096325ms] java.util.jar.JarFile:getInputStream() #111  
        +---[0.451916ms] org.apache.catalina.webresources.TomcatJarInputStream:<init>() #113  
        +---[min=0.001175ms,max=0.001176ms,total=0.002351ms,count=2] java.lang.Integer:<init>() #114  
        +---[0.00104ms] java.lang.reflect.Method:invoke() #114  
        +---[0.045105ms] org.apache.catalina.webresources.TomcatJarInputStream:getNextJarEntry() #114  
        +---[min=5.02E-4ms,max=0.008531ms,total=0.028864ms,count=31] java.util.jar.JarEntry:getName() #116  
        +---[min=5.39E-4ms,max=0.022805ms,total=0.054647ms,count=31] java.util.HashMap:put() #116  
        +---[min=0.004452ms,max=34.479307ms,total=74.206249ms,count=31] org.apache.catalina.webresources.TomcatJarInputStream:getNextJarEntry() #117  
        +---[0.018358ms] org.apache.catalina.webresources.TomcatJarInputStream:getManifest() #119  
        +---[0.006429ms] org.apache.catalina.webresources.JarWarResourceSet:setManifest() #120  
        +---[0.010904ms] org.apache.tomcat.util.compat.JreCompat:isJre9Available() #121  
        +---[0.003307ms] org.apache.catalina.webresources.TomcatJarInputStream:getMetaInfEntry() #133  
        +---[5.5E-4ms] java.util.jar.JarEntry:getName() #135  
        +---[6.42E-4ms] java.util.HashMap:put() #135  
        +---[0.001981ms] org.apache.catalina.webresources.TomcatJarInputStream:getManifestEntry() #137  
        +---[0.064484ms] org.apache.catalina.webresources.TomcatJarInputStream:close() #141  
        +---[0.007961ms] org.apache.catalina.webresources.JarWarResourceSet:closeJarFile() #151  
        `---[0.004643ms] java.io.InputStream:close() #155

發(fā)現(xiàn)了一個(gè)值得暫停思考的點(diǎn)：

+---[min=0.004452ms,max=34.479307ms,total=74.206249ms,count=31] org.apache.catalina.webresources.TomcatJarInputStream:getNextJarEntry() #117

這行代碼加載了31次，一共耗時(shí)74ms；從名字上看，應(yīng)該是tomcat加載jar包時(shí)的耗時(shí)，那么是加載了31個(gè)jar包的耗時(shí)，還是加載了jar包內(nèi)的某些資源31次耗時(shí)呢？

TomcatJarInputStream這個(gè)類源碼的注釋寫到：

The purpose of this sub-class is to obtain references to the JarEntry objects for META-INF/ and META-INF/MANIFEST.MF that are otherwise swallowed by the JarInputStream implementation.

大概意思也就是，獲取jar包內(nèi)META-INF/，META-INF/MANIFEST的資源，這是一個(gè)子類，更多的功能在父類JarInputStream里。

其實(shí)看到這里大概也能猜到問題了，tomcat加載jar包內(nèi)META-INF/，META-INF/MANIFEST的資源導(dǎo)致的耗時(shí)，至于為什么連續(xù)請(qǐng)求不會(huì)耗時(shí)，應(yīng)該是tomcat的緩存機(jī)制（下面介紹源碼分析）不著急定位問題，試著通過Arthas最終定位問題細(xì)節(jié)，繼續(xù)手動(dòng)深入trace

[arthas@24851]$ trace org.apache.catalina.webresources.TomcatJarInputStream *  
Press Q or Ctrl+C to abort.  
Affect(class-cnt:1 , method-cnt:4) cost in 44 ms.  
`---ts=2019-09-14 21:37:47;thread_name=http-nio-7744-exec-5;id=14;is_daemon=true;priority=5;TCCL=org.springframework.boot.loader.LaunchedURLClassLoader@20ad9418  
    `---[0.234952ms] org.apache.catalina.webresources.TomcatJarInputStream:createZipEntry()  
        +---[0.039455ms] java.util.jar.JarInputStream:createZipEntry() #43  
        `---[0.007827ms] java.lang.String:equals() #44  
  
`---ts=2019-09-14 21:37:47;thread_name=http-nio-7744-exec-5;id=14;is_daemon=true;priority=5;TCCL=org.springframework.boot.loader.LaunchedURLClassLoader@20ad9418  
    `---[0.050222ms] org.apache.catalina.webresources.TomcatJarInputStream:createZipEntry()  
        +---[0.001889ms] java.util.jar.JarInputStream:createZipEntry() #43  
        `---[0.001643ms] java.lang.String:equals() #46  
#這里一共31個(gè)trace日志，刪減了剩下的

從方法名上看，還是加載資源之類的意思。都已經(jīng)到j(luò)dk源碼了，這時(shí)候來看一下TomcatJarInputStream這個(gè)類的源碼:

/**  
 * Creates a new <code>JarEntry</code> (<code>ZipEntry</code>) for the  
 * specified JAR file entry name. The manifest attributes of  
 * the specified JAR file entry name will be copied to the new  
 * <CODE>JarEntry</CODE>.  
 *  
 * @param name the name of the JAR/ZIP file entry  
 * @return the <code>JarEntry</code> object just created  
 */  
protected ZipEntry createZipEntry(String name) {  
    JarEntry e = new JarEntry(name);  
    if (man != null) {  
        e.attr = man.getAttributes(name);  
    }  
    return e;  
}

這個(gè)createZipEntry有個(gè)name參數(shù)，從注釋上看，是jar/zip文件名，如果能得到文件名這種關(guān)鍵信息，就可以直接定位問題了；還是通過Arthas，使用watch命令，動(dòng)態(tài)監(jiān)測(cè)方法調(diào)用數(shù)據(jù)

1.watch方法執(zhí)行數(shù)據(jù)觀測(cè)

讓你能方便的觀察到指定方法的調(diào)用情況。能觀察到的范圍為：返回值、拋出異常、入?yún)ⅲㄟ^編寫 OGNL 表達(dá)式進(jìn)行對(duì)應(yīng)變量的查看。

watch 該方法的入?yún)ⅲ?/p>

[arthas@24851]$ watch  org.apache.catalina.webresources.TomcatJarInputStream createZipEntry "{params[0]}"  
Press Q or Ctrl+C to abort.  
Affect(class-cnt:1 , method-cnt:1) cost in 27 ms.  
ts=2019-09-14 21:51:14; [cost=0.14547ms] result=@ArrayList[  
    @String[META-INF/],  
]  
ts=2019-09-14 21:51:14; [cost=0.048028ms] result=@ArrayList[  
    @String[META-INF/MANIFEST.MF],  
]  
ts=2019-09-14 21:51:14; [cost=0.046071ms] result=@ArrayList[  
    @String[META-INF/resources/],  
]  
ts=2019-09-14 21:51:14; [cost=0.033855ms] result=@ArrayList[  
    @String[META-INF/resources/swagger-ui.html],  
]  
ts=2019-09-14 21:51:14; [cost=0.039138ms] result=@ArrayList[  
    @String[META-INF/resources/webjars/],  
]  
ts=2019-09-14 21:51:14; [cost=0.033701ms] result=@ArrayList[  
    @String[META-INF/resources/webjars/springfox-swagger-ui/],  
]  
ts=2019-09-14 21:51:14; [cost=0.033644ms] result=@ArrayList[  
    @String[META-INF/resources/webjars/springfox-swagger-ui/favicon-16x16.png],  
]  
ts=2019-09-14 21:51:14; [cost=0.033976ms] result=@ArrayList[  
    @String[META-INF/resources/webjars/springfox-swagger-ui/springfox.css],  
]  
ts=2019-09-14 21:51:14; [cost=0.032818ms] result=@ArrayList[  
    @String[META-INF/resources/webjars/springfox-swagger-ui/swagger-ui-standalone-preset.js.map],  
]  
ts=2019-09-14 21:51:14; [cost=0.04651ms] result=@ArrayList[  
    @String[META-INF/resources/webjars/springfox-swagger-ui/swagger-ui.css],  
]  
ts=2019-09-14 21:51:14; [cost=0.034793ms] result=@ArrayList[  
    @String[META-INF/resources/webjars/springfox-swagger-ui/swagger-ui.js.map],

這下直接看到了具體加載的資源名，這么熟悉的名字：swagger-ui，一個(gè)國外的rest接口文檔工具，又有國內(nèi)開發(fā)者基于swagger-ui做了一套spring mvc的集成工具，通過注解就可以自動(dòng)生成swagger-ui需要的接口定義json文件，用起來還比較方便，就是侵入性較強(qiáng)。

刪除swagger的jar包后問題，詭異的70+ms就消失了：

<!--pom 里刪除這兩個(gè)引用，這兩個(gè)包時(shí)國內(nèi)開發(fā)者封裝的，swagger-ui并沒有提供java spring-mvc的支持包，swagger只是一個(gè)瀏覽器端的ui+editor -->  
<dependency>  
    <groupId>io.springfox</groupId>  
    <artifactId>springfox-swagger2</artifactId>  
    <version>2.9.2</version>  
</dependency>  
<dependency>  
    <groupId>io.springfox</groupId>  
    <artifactId>springfox-swagger-ui</artifactId>  
    <version>2.9.2</version>  
</dependency>

那么為什么swagger會(huì)導(dǎo)致請(qǐng)求耗時(shí)呢，為什么每次請(qǐng)求偶讀會(huì)加載swagger內(nèi)部的靜態(tài)資源呢？

其實(shí)這是tomcat-embed的一個(gè)bug吧，下面詳細(xì)介紹一下該Bug

2.Tomcat embed Bug分析&解決

源碼分析過程實(shí)在太漫長(zhǎng)，而且也不是本文的重點(diǎn)，所以就不介紹了， 下面直接介紹下分析結(jié)果，順便貼一張tomcat處理請(qǐng)求的核心類圖：

(1) 為什么每次請(qǐng)求會(huì)加載Jar包內(nèi)的靜態(tài)資源

關(guān)鍵在于org.apache.catalina.mapper.Mapper#internalMapWrapper這個(gè)方法，該版本下處理請(qǐng)求的方式有問題，導(dǎo)致每次都校驗(yàn)靜態(tài)資源。

(2) 為什么連續(xù)請(qǐng)求不會(huì)出現(xiàn)問題

因?yàn)門omcat對(duì)于這種靜態(tài)資源的解析是有緩存的，優(yōu)先從緩存查找，緩存過期后再重新解析。具體參考o(jì)rg.apache.catalina.webresources.Cache，默認(rèn)過期時(shí)間ttl是5000ms。

(3) 為什么本地不會(huì)復(fù)現(xiàn)

其實(shí)確切的說，是通過spring-boot打包插件后不能復(fù)現(xiàn)。由于啟動(dòng)方式的不同，tomcat使用了不同的類去處理靜態(tài)資源，所以沒問題。

(4) 如何解決

升級(jí)tomcat-embed版本即可。

當(dāng)前出現(xiàn)Bug的版本為：

  • spring-boot:2.0.2.RELEASE，內(nèi)置的tomcat embed版本為8.5.31
  • 升級(jí)tomcat embed版本至8.5.40+即可解決此問題，新版本已經(jīng)修復(fù)了

3.通過替換springboot pom properties方式

如果項(xiàng)目是maven是繼承的springboot，即parent配置為springboot的，或者dependencyManagement中import spring boot包的：

<parent>  
    <groupId>org.springframework.boot</groupId>  
    <artifactId>spring-boot-starter-parent</artifactId>  
    <version>2.0.2.RELEASE</version>  
    <relativePath/> <!-- lookup parent from repository -->  
</parent>

pom中直接覆蓋properties即可：

<properties>  
    <tomcat.version>8.5.40</tomcat.version>  
</properties>

升級(jí)spring boot版本：springboot 2.1.0.RELEASE中的tomcat embed版本已經(jīng)大于8.5.31了，所以直接將springboot升級(jí)至該版本及以上版本就可以解決此問題。

責(zé)任編輯：趙寧寧 來源： 技術(shù)老男孩
ArthasSpring
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