公司有個(gè)渠道系統(tǒng)，專門對(duì)接三方渠道使用去团，沒有什么業(yè)務(wù)邏輯抡诞，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)承上啟下的作用土陪。
最近在優(yōu)化接口的響應(yīng)時(shí)間昼汗，優(yōu)化了代碼之后，但是時(shí)間還是達(dá)不到要求鬼雀；有一個(gè)詭異的100ms左右的耗時(shí)問題顷窒，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左右源哩。比如程序里記錄150ms鞋吉，但是調(diào)用方等待時(shí)間卻為250ms左右鸦做。
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）
定位過程
分析代碼
渠道系統(tǒng)是一個(gè)常見的spring-boot web工程谓着，使用了集成的tomcat泼诱。分析了代碼之后，發(fā)現(xiàn)并沒有特殊的地方漆魔，沒有特殊的過濾器或者攔截器坷檩，所以初步排除是業(yè)務(wù)代碼問題
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)用流程改抡。由于是內(nèi)部測(cè)試矢炼，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)器阿纤，網(wǎng)絡(luò)走的也是云的內(nèi)網(wǎng)句灌。由于不明確問題的原因，所以用排除法欠拾，首先確認(rèn)服務(wù)器網(wǎng)絡(luò)是否有問題胰锌。
先確認(rèn)發(fā)送端到Nginx Host是否有問題：
[jboss@VM_0_139_centos?~]$?ping10.0.0.139
PING10.0.0.139(10.0.0.139)56(84)?bytes?of?data.
64bytes?from10.0.0.139:?icmp_seq=1ttl=64time=0.029ms
64bytes?from10.0.0.139:?icmp_seq=2ttl=64time=0.041ms
64bytes?from10.0.0.139:?icmp_seq=3ttl=64time=0.040ms
64bytes?from10.0.0.139:?icmp_seq=4ttl=64time=0.040ms
從ping結(jié)果上看，發(fā)送端到Nginx主機(jī)的延遲是無(wú)問題的藐窄，接下來查看Nginx到渠道系統(tǒng)的網(wǎng)絡(luò)资昧。
#?由于日志是沒問題的，這里直接復(fù)制上面日志了
[jboss@VM_0_139_centos?~]$?ping10.0.0.139
PING10.0.0.139(10.0.0.139)56(84)?bytes?of?data.
64bytes?from10.0.0.139:?icmp_seq=1ttl=64time=0.029ms
64bytes?from10.0.0.139:?icmp_seq=2ttl=64time=0.041ms
64bytes?from10.0.0.139:?icmp_seq=3ttl=64time=0.040ms
64bytes?from10.0.0.139:?icmp_seq=4ttl=64time=0.040ms
從ping結(jié)果上看荆忍，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)看似沒問題格带，那么可以繼續(xù)排除法，砍掉Nginx刹枉，客戶端直接再渠道系統(tǒng)的服務(wù)器上叽唱，通過回環(huán)地址（localhost）直連，避免經(jīng)過網(wǎng)卡/dns微宝，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棺亭，測(cè)試的是一個(gè)空接口）：
[jboss@VM_10_91_centos?tmp]$?curl?-w"@curl-time.txt"http://127.0.0.1:7744/send
success
http:200
dns:0.001s
redirect:0.000s
time_connect:0.001s
time_appconnect:0.000s
time_pretransfer:0.001s
time_starttransfer:0.073s
size_download:7bytes
speed_download:95.000B/s
----------
time_total:0.073s?請(qǐng)求總耗時(shí)
從curl日志上看，通過回環(huán)地址調(diào)用一個(gè)空接口耗時(shí)也有73ms蟋软。這就奇怪了镶摘，跳過了中間所有調(diào)用節(jié)點(diǎn)（包括過濾器&攔截器之類），直接請(qǐng)求應(yīng)用一個(gè)空接口岳守，都有73ms的耗時(shí)钉稍，再請(qǐng)求一次看看：
[jboss@VM_10_91_centos?tmp]$?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)就正常了棺耍，變成了3ms。經(jīng)查閱資料种樱，linux curl是默認(rèn)開啟http keep-alive的蒙袍。就算不開啟keep-alive俊卤，每次重新handshake，也不至于需要70ms害幅。
經(jīng)過不斷分析測(cè)試發(fā)現(xiàn)消恍，連續(xù)請(qǐng)求的話時(shí)間就會(huì)很短，每次請(qǐng)求只需要幾毫秒以现，但是如果隔一段時(shí)間再請(qǐng)求狠怨，就會(huì)花費(fèi)70ms以上。
從這個(gè)現(xiàn)象猜想邑遏，可能是某些緩存機(jī)制導(dǎo)致的佣赖，連續(xù)請(qǐng)求因?yàn)橛芯彺妫运俣瓤旒呛校瑫r(shí)間長(zhǎng)緩存失效后導(dǎo)致時(shí)間長(zhǎng)憎蛤。
那么這個(gè)問題點(diǎn)到底在哪一層呢？tomcat層還是spring-webmvc呢纪吮？
光猜想定位不了問題俩檬，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后碾盟，在Ide中啟動(dòng)后并不能復(fù)現(xiàn)問題棚辽，并沒有70+ms的延遲問題。這下頭疼了冰肴，本地?zé)o法復(fù)現(xiàn)屈藐，不能Debug，由于問題點(diǎn)不在業(yè)務(wù)代碼嚼沿，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
Arthas分析問題
Arthas 是Alibaba開源的Java診斷工具估盘，深受開發(fā)者喜愛。當(dāng)你遇到以下類似問題而束手無(wú)策時(shí)骡尽，Arthas可以幫助你解決：
這個(gè)類從哪個(gè) jar 包加載的遣妥？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)行到攀细？難道是我沒 commit箫踩？分支搞錯(cuò)了？
遇到問題無(wú)法在線上 debug谭贪，難道只能通過加日志再重新發(fā)布嗎境钟？
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(wú)法 debug俭识，線下無(wú)法重現(xiàn)慨削！
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)介缚态，這次我只需要用他的一個(gè)小功能trace磁椒。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)地方被消耗了玫芦。
trace 方法內(nèi)部調(diào)用路徑浆熔，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)用鏈路桥帆。
有了神器医增，那該追蹤什么方法呢？由于我對(duì)Tomcat源碼不是很熟老虫，所以只能從spring mvc下手叶骨，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)costin508ms.
`---ts
=2019-09-1421:07:44;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=2019-09-1421:07:44;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:()?#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:()?#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张遭，但是從arthas trace上看邓萨，spring mvc只消耗了18ms，那么剩下的97ms去哪了呢菊卷？
本地測(cè)試后已經(jīng)可以排除spring mvc的問題了缔恳，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)求入口都不清楚洁闰，tomcat里需要trace的類都不好找歉甚。。扑眉。
不過沒關(guān)系纸泄，有神器Arthas，可以通過stack命令來反向查找調(diào)用路徑腰素，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)行聘裁，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)行了弓千，此時(shí)你需要的是 stack 命令衡便。
[arthas@24851]$?stack?org.springframework.web.servlet.DispatcherServlet?*
Press?Q?or?Ctrl+C?to?abort.
Affect(class-cnt:1?,method-cnt:44)costin495ms.
ts
=2019-09-1421:15:19;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=2019-09-1421:15:19;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$WrappingRunnable.run(TaskThread.java:61)
at?java.lang.Thread.run(Thread.java:748)
從stack日志上可以很直觀的看出DispatchServlet的調(diào)用棧，那么這么長(zhǎng)的路徑洋访，該trace哪個(gè)類呢（這里跳過spring mvc中的過濾器的trace過程镣陕，實(shí)際排查的時(shí)候也trace了一遍，但這詭異的時(shí)間消耗不是由這里過濾器產(chǎn)生的）姻政？
有一定經(jīng)驗(yàn)的老司機(jī)從名字上大概也能猜出來從哪里下手比較好呆抑，那就是org.apache.coyote.http11.Http11Processor.service，從名字上看汁展，http1.1處理器鹊碍，這可能是一個(gè)比較好的切入點(diǎn)厌殉。下面來trace一下：
[arthas@24851]$?trace?org.apache.coyote.http11.Http11Processor?service
Press?Q?or?Ctrl+C?to?abort.
Affect(class-cnt:1?,method-cnt:1)costin269ms.
`---ts
=2019-09-1421:22:51;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）侈咕，這個(gè)就是要找的問題點(diǎn)年枕。
打問題點(diǎn)找到了，那怎么定位是什么導(dǎo)致的問題呢乎完，又如何解決呢品洛？
繼續(xù)trace吧树姨，細(xì)化到具體的代碼塊或者內(nèi)容。trace由于性能考慮桥状，不會(huì)展示所有的調(diào)用路徑帽揪，如果調(diào)用路徑過深，只有手動(dòng)深入trace辅斟，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)costin608ms.
`---ts
=2019-09-1421:34:33;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:()?#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:()?#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(wú)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)costin150ms.
`---ts
=2019-09-1421:36:26;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:()?#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:()?#113
+---[min=0.001175ms,max=0.001176ms,total=0.002351ms,count=2]?java.lang.Integer:()?#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次转晰，一共耗時(shí)74ms；從名字上看士飒，應(yīng)該是tomcat加載jar包時(shí)的耗時(shí)查邢，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)呢酵幕？
TomcatJarInputStream這個(gè)類源碼的注釋寫到：
The?purpose?ofthissub-classistoobtainreferencestotheJarEntryobjectsforMETA-INF/andMETA-INF/MANIFEST.MFthatareotherwiseswallowedbytheJarInputStreamimplementation.
大概意思也就是扰藕，獲取jar包內(nèi)META-INF/，META-INF/MANIFEST的資源芳撒，這是一個(gè)子類邓深，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笔刹，tomcat加載jar包內(nèi)META-INF/芥备，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)舌菜，應(yīng)該是tomcat的緩存機(jī)制（下面介紹源碼分析）
不著急定位問題萌壳，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]$?trace?org.apache.catalina.webresources.TomcatJarInputStream?*
Press?Q?or?Ctrl+C?to?abort.
Affect(class-cnt:1?,method-cnt:4)costin44ms.
`---ts
=2019-09-1421:37:47;thread_name=http-nio-7744-exec-5;id=14;is_daemon=true;priority=5;TCCL=org.springframework.boot.loader.LaunchedURLClassLoader@20ad9418
`---[0.234952ms]?org.apache.catalina.webresources.TomcatJarInputStream:createZipEntry()
+---[0.039455ms]?java.util.jar.JarInputStream:createZipEntry()?#43
`---[0.007827ms]?java.lang.String:equals()?#44
`---ts=2019-09-1421:37:47;thread_name=http-nio-7744-exec-5;id=14;is_daemon=true;priority=5;TCCL=org.springframework.boot.loader.LaunchedURLClassLoader@20ad9418
`---[0.050222ms]?org.apache.catalina.webresources.TomcatJarInputStream:createZipEntry()
+---[0.001889ms]?java.util.jar.JarInputStream:createZipEntry()?#43
`---[0.001643ms]?java.lang.String:equals()?#46
#這里一共31個(gè)trace日志酷师，刪減了剩下的
從方法名上看讶凉，還是加載資源之類的意思。都已經(jīng)到j(luò)dk源碼了山孔，這時(shí)候來看一下TomcatJarInputStream這個(gè)類的源碼:
/**
*?Creates?a?new?JarEntry?(ZipEntry)?for?the
*?specified?JAR?file?entry?name.?The?manifest?attributes?of
*?the?specified?JAR?file?entry?name?will?be?copied?to?the?new
*?JarEntry.
*
*@paramname?the?name?of?the?JAR/ZIP?file?entry
*@returnthe?JarEntry?object?just?created
*/
protectedZipEntrycreateZipEntry(String?name){
JarEntry?e?=newJarEntry(name);
if(man?!=null)?{
e.attr?=?man.getAttributes(name);
}
returne;
}
這個(gè)createZipEntry有個(gè)name參數(shù)懂讯，從注釋上看，是jar/zip文件名台颠，如果能得到文件名這種關(guān)鍵信息褐望，就可以直接定位問題了勒庄；還是通過Arthas，使用watch命令瘫里，動(dòng)態(tài)監(jiān)測(cè)方法調(diào)用數(shù)據(jù)watch方法執(zhí)行數(shù)據(jù)觀測(cè)实蔽。
讓你能方便的觀察到指定方法的調(diào)用情況。能觀察到的范圍為：返回值谨读、拋出異常局装、入?yún)ⅲㄟ^編寫 OGNL 表達(dá)式進(jìn)行對(duì)應(yīng)變量的查看劳殖。
watch 該方法的入?yún)?/p>
[arthas@24851]$?watch??org.apache.catalina.webresources.TomcatJarInputStream?createZipEntry"{params[0]}"
Press?Q?or?Ctrl+C?to?abort.
Affect(class-cnt:1?,method-cnt:1)costin27ms.
ts
=2019-09-1421:51:14;?[cost=0.14547ms]?result=@ArrayList[
@String[META-INF/],
]
ts=2019-09-1421:51:14;?[cost=0.048028ms]?result=@ArrayList[
@String[META-INF/MANIFEST.MF],
]
ts=2019-09-1421:51:14;?[cost=0.046071ms]?result=@ArrayList[
@String[META-INF/resources/],
]
ts=2019-09-1421:51:14;?[cost=0.033855ms]?result=@ArrayList[
@String[META-INF/resources/swagger-ui.html],
]
ts=2019-09-1421:51:14;?[cost=0.039138ms]?result=@ArrayList[
@String[META-INF/resources/webjars/],
]
ts=2019-09-1421:51:14;?[cost=0.033701ms]?result=@ArrayList[
@String[META-INF/resources/webjars/springfox-swagger-ui/],
]
ts=2019-09-1421:51:14;?[cost=0.033644ms]?result=@ArrayList[
@String[META-INF/resources/webjars/springfox-swagger-ui/favicon-16x16.png],
]
ts=2019-09-1421:51:14;?[cost=0.033976ms]?result=@ArrayList[
@String[META-INF/resources/webjars/springfox-swagger-ui/springfox.css],
]
ts=2019-09-1421:51:14;?[cost=0.032818ms]?result=@ArrayList[
@String[META-INF/resources/webjars/springfox-swagger-ui/swagger-ui-standalone-preset.js.map],
]
ts=2019-09-1421:51:14;?[cost=0.04651ms]?result=@ArrayList[
@String[META-INF/resources/webjars/springfox-swagger-ui/swagger-ui.css],
]
ts=2019-09-1421:51:14;?[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铐尚，這么熟悉的名字：swagger-ui，一個(gè)國(guó)外的rest接口文檔工具哆姻，又有國(guó)內(nèi)開發(fā)者基于swagger-ui做了一套spring mvc的集成工具宣增，通過注解就可以自動(dòng)生成swagger-ui需要的接口定義json文件，用起來還比較方便矛缨，就是侵入性較強(qiáng)爹脾。
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)引用箕昭，這兩個(gè)包時(shí)國(guó)內(nèi)開發(fā)者封裝的灵妨，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?-->
io.springfox
springfox-swagger2
2.9.2
io.springfox
springfox-swagger-ui
2.9.2
那么為什么swagger會(huì)導(dǎo)致請(qǐng)求耗時(shí)呢盟广，為什么每次請(qǐng)求偶讀會(huì)加載swagger內(nèi)部的靜態(tài)資源呢闷串？
其實(shí)這是tomcat-embed的一個(gè)bug吧，下面詳細(xì)介紹一下該Bug
Tomcat embed Bug分析&解決
源碼分析過程實(shí)在太漫長(zhǎng)筋量，而且也不是本文的重點(diǎn)烹吵，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
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)方法桨武，該版本下處理請(qǐng)求的方式有問題肋拔，導(dǎo)致每次都校驗(yàn)靜態(tài)資源。
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呀酸，優(yōu)先從緩存查找凉蜂，緩存過期后再重新解析。具體參考o(jì)rg.apache.catalina.webresources.Cache性誉，默認(rèn)過期時(shí)間ttl是5000ms窿吩。
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)错览。由于啟動(dòng)方式的不同纫雁，tomcat使用了不同的類去處理靜態(tài)資源，所以沒問題
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倾哺，內(nèi)置的tomcat embed版本為8.5.31
升級(jí)tomcat embed版本至8.5.40+即可解決此問題轧邪，新版本已經(jīng)修復(fù)了
通過替換springboot pom properties方式
如果項(xiàng)目是maven是繼承的springboot刽脖，即parent配置為springboot的，或者dependencyManagement中import spring boot包的
org.springframework.boot
spring-boot-starter-parent
2.0.2.RELEASE
<!--?lookup?parent?from?repository?-->
pom中直接覆蓋properties即可：
8.5.40
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了忌愚，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曲管。
