Spring boot應(yīng)用在ECS服務(wù)器上啟動(dòng)后首次訪問(wèn)很慢的問(wèn)題環(huán)境： CentOS7 JDK1.8 MYSQL8 應(yīng)用是Spring boot框架的（內(nèi)嵌式tomcat）jar文件問(wèn)題描述：

通過(guò)命令：nohup java -jar XXXX.jar & 啟動(dòng)項(xiàng)目后瀏覽器訪問(wèn)響應(yīng)十分的緩慢，網(wǎng)頁(yè)圖片和css等靜態(tài)資源加載的十分緩慢（網(wǎng)站登錄更是需要好幾分鐘才能完全加載完畢）。

然后在Google瀏覽器搜索了一下（已翻墻），搜索需用英文，類似問(wèn)題看來(lái)不是個(gè)例呀，甚至JDK bug列表匯中就有相似的bug，如JDK-6521844 : SecureRandom hangs on Linux Systems，但這些bug都標(biāo)記為fixed。但明顯沒(méi)有完全fix掉啊。然后繼續(xù)找，原來(lái)

Avoiding JVM Delays Caused by Random Number Generation

正好記錄了這個(gè)隨機(jī)數(shù)生成慢的原因和解決方案。Java隨機(jī)數(shù)生成依賴熵源（Entropy Source），默認(rèn)的阻塞型的 /dev/random熵源可能導(dǎo)致阻塞，而換一個(gè)非阻塞的 /dev/urandom的熵源就可以了。

進(jìn)入你的JAVA_HOME的jre目錄下找到并vim編輯這個(gè)文件：

$JAVA_HOME/jre/lib/security/java.security

找到：

securerandom.source=file:/dev/random 這一行

改之前：

securerandom.source=file:/dev/random

改為：

securerandom.source=file:/dev/urandom

然后保存修改就OK了！

Spring boot靜態(tài)資源訪問(wèn)太慢

產(chǎn)生的問(wèn)題：

spring boot 啟動(dòng)的服務(wù)靜態(tài)資源非常慢，慢到無(wú)法忍受。

排查過(guò)程 一

1. 在filter 中記錄請(qǐng)求時(shí)間 ，得到某些靜態(tài)資源居然600ms，但是主要問(wèn)題不在這里，是客戶端的連接被阻塞了。如上圖

2. 然后然后禁用filter（直接spring boot static） 返回

3. 結(jié)果還是很慢

排查過(guò)程 二

1. 開(kāi)啟客戶端資源 GZIP

2. 手動(dòng)設(shè)置cache-contro

結(jié)果還是很慢，我就很疑惑了，難道是選用的資源有問(wèn)題，看著也很正常。

于是我就把資源都放到 python flask！！ 結(jié)果比java的快了好幾倍。。 瞬間我人就蒙了。

然后仔細(xì)看application.xml 配置，其實(shí)當(dāng)時(shí)也沒(méi)設(shè)置什么東西 ，于是一項(xiàng)一項(xiàng)的注釋，效率上還是沒(méi)變化，我就試了試新建一個(gè)項(xiàng)目，然后把 html 都拿過(guò)去。

問(wèn)題解決了！！ 速度 非常快

好家伙，我直接好家伙，我查了幾天的問(wèn)題，居然可能是在依賴上。

最后結(jié)論 ：應(yīng)該是某一個(gè)依賴項(xiàng)有問(wèn)題導(dǎo)致的，或者版本本身不對(duì)勁

有空再去看看2.3.4 的 底層tomcat配置有什么不同

有問(wèn)題的配置

<?xml version='1.0' encoding='UTF-8'?><project xmlns='http://maven.apache.org/POM/4.0.0' xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' xsi:schemaLocation='http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd'> <modelVersion>4.0.0</modelVersion> <parent><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-parent</artifactId><version>2.3.4.RELEASE</version><relativePath/> <!-- lookup parent from repository --> </parent> <groupId>com.tianlun</groupId> <artifactId>tianlunpc</artifactId> <version>0.0.1-SNAPSHOT</version> <name>tianlunpc</name> <description>Demo project for Spring Boot</description> <properties><java.version>1.8</java.version> </properties> <dependencies><dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-jpa</artifactId></dependency><dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-thymeleaf</artifactId></dependency><dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId></dependency><dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <scope>runtime</scope></dependency><dependency> <groupId>org.projectlombok</groupId> <artifactId>lombok</artifactId> <optional>true</optional></dependency><dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> <exclusions><exclusion> <groupId>org.junit.vintage</groupId> <artifactId>junit-vintage-engine</artifactId></exclusion> </exclusions></dependency><!-- session jdbc --><dependency> <groupId>org.springframework.session</groupId> <artifactId>spring-session-jdbc</artifactId></dependency><!--熱部署--><dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-devtools</artifactId> <optional>true</optional></dependency> </dependencies> <build><plugins> <plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId> </plugin></plugins> </build></project>沒(méi)問(wèn)題的配置

<?xml version='1.0' encoding='UTF-8'?><project xmlns='http://maven.apache.org/POM/4.0.0' xmlns:xsi='http://www.w3.org/2001/XMLSchema-instance' xsi:schemaLocation='http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd'> <modelVersion>4.0.0</modelVersion> <groupId>com.tianlun</groupId> <artifactId>tianlinpc</artifactId> <version>0.0.1-SNAPSHOT</version> <name>tianlinpc</name> <description>Demo project for Spring Boot</description> <properties><java.version>1.8</java.version><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding><project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding><spring-boot.version>2.3.7.RELEASE</spring-boot.version> </properties> <dependencies><dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-data-jpa</artifactId></dependency><dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-thymeleaf</artifactId></dependency><dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-web</artifactId></dependency><dependency> <groupId>commons-io</groupId> <artifactId>commons-io</artifactId> <version>2.6</version></dependency><dependency> <groupId>org.springframework.session</groupId> <artifactId>spring-session-core</artifactId></dependency><dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <scope>runtime</scope></dependency><!--熱部署--><dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-devtools</artifactId> <optional>true</optional></dependency><dependency> <groupId>org.projectlombok</groupId> <artifactId>lombok</artifactId> <optional>true</optional></dependency><dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> <exclusions><exclusion> <groupId>org.junit.vintage</groupId> <artifactId>junit-vintage-engine</artifactId></exclusion> </exclusions></dependency> </dependencies> <dependencyManagement><dependencies> <dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-dependencies</artifactId><version>${spring-boot.version}</version><type>pom</type><scope>import</scope> </dependency></dependencies> </dependencyManagement> <build><plugins> <plugin><groupId>org.apache.maven.plugins</groupId><artifactId>maven-compiler-plugin</artifactId><version>3.8.1</version><configuration> <source>1.8</source> <target>1.8</target> <encoding>UTF-8</encoding></configuration> </plugin> <plugin><groupId>org.springframework.boot</groupId><artifactId>spring-boot-maven-plugin</artifactId><version>2.3.7.RELEASE</version><configuration> <mainClass>com.tianlun.tianlunpc.TianlinpcApplication</mainClass></configuration><executions> <execution><id>repackage</id><goals> <goal>repackage</goal></goals> </execution></executions> </plugin></plugins> </build></project>

以上為個(gè)人經(jīng)驗(yàn)，希望能給大家一個(gè)參考，也希望大家多多支持好吧啦網(wǎng)。