類數(shù)據(jù)共享 (CDS) 是一項 JVM 功能,可幫助減少 Java 應(yīng)用程序的啟動時間和內(nèi)存占用。從 JDK 12 開始,默認(rèn)的 CDS 歸檔文件與 Oracle JDK 二進(jìn)制文件一起預(yù)打包。筆者測試使用的 OpenJDK 64-Bit Server VM Zulu21.34+19-CA (build 21.0.3+9-LTS, mixed mode, sharing)它也是支持 CDS 的。
要使用它,您應(yīng)該首先以分解形式對應(yīng)用程序執(zhí)行訓(xùn)練運行:
$ java -Djarmode=tools -jar my-app.jar extract --destination application$ cd application$ java -XX:ArchiveClassesAtExit=application.jsa -Dspring.context.exit=onRefresh -jar my-app.jar
這將創(chuàng)建一個 application 目錄并生成 application.jsa,只要應(yīng)用程序未更新,就可以重復(fù)使用。
要使用緩存,您需要在啟動應(yīng)用程序時添加一個額外的 -XX:SharedArchiveFile 參數(shù):
$ java -XX:SharedArchiveFile=application.jsa -jar my-app.jar
為了測試 CDS,筆者使用 Spring Boot initializr 生成了一個 demo 項目。下面是 CDS 訓(xùn)練后的 application 目錄的結(jié)構(gòu):
$ tree applicationapplication|-- application.jsa|-- demo-0.0.1-SNAPSHOT.jar`-- lib |-- jackson-annotations-2.17.1.jar |-- jackson-core-2.17.1.jar |-- jackson-databind-2.17.1.jar |-- jackson-datatype-jdk8-2.17.1.jar |-- jackson-datatype-jsr310-2.17.1.jar |-- jackson-module-parameter-names-2.17.1.jar |-- jakarta.annotation-api-2.1.1.jar |-- jul-to-slf4j-2.0.13.jar |-- log4j-api-2.23.1.jar |-- log4j-to-slf4j-2.23.1.jar |-- logback-classic-1.5.6.jar |-- logback-core-1.5.6.jar |-- micrometer-commons-1.13.0.jar |-- micrometer-observation-1.13.0.jar |-- slf4j-api-2.0.13.jar |-- snakeyaml-2.2.jar |-- spring-aop-6.1.8.jar |-- spring-beans-6.1.8.jar |-- spring-boot-3.3.0.jar |-- spring-boot-autoconfigure-3.3.0.jar |-- spring-boot-jarmode-tools-3.3.0.jar |-- spring-context-6.1.8.jar |-- spring-core-6.1.8.jar |-- spring-expression-6.1.8.jar |-- spring-jcl-6.1.8.jar |-- spring-web-6.1.8.jar |-- spring-webmvc-6.1.8.jar |-- tomcat-embed-core-10.1.24.jar |-- tomcat-embed-el-10.1.24.jar `-- tomcat-embed-websocket-10.1.24.jar1 directory, 32 files
$ java -jar demo-0.0.1-SNAPSHOT.jar . ____ _ __ _ _ /// / ___'_ __ _ _(_)_ __ __ _ / / / /( ( )/___ | '_ | '_| | '_ // _` | / / / / /// ___)| |_)| | | | | || (_| | ) ) ) ) ' |____| .__|_| |_|_| |_/__, | / / / / =========|_|==============|___/=/_/_/_/ :: Spring Boot :: (v3.3.0)2024-05-31T08:53:39.964+08:00 INFO 14832 --- [demo] [ main] com.example.demo.DemoApplication : Starting DemoApplication v0.0.1-SNAPSHOT using Java 21.0.3 with PID 14832 (D:/test/demo/target/demo-0.0.1-SNAPSHOT.jar started by L.cm in D:/test/demo/target)2024-05-31T08:53:39.967+08:00 INFO 14832 --- [demo] [ main] com.example.demo.DemoApplication : No active profile set, falling back to 1 default profile: "default"2024-05-31T08:53:40.893+08:00 INFO 14832 --- [demo] [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat initialized with port 8888 (http)2024-05-31T08:53:40.908+08:00 INFO 14832 --- [demo] [ main] o.apache.catalina.core.StandardService : Starting service [Tomcat]2024-05-31T08:53:40.908+08:00 INFO 14832 --- [demo] [ main] o.apache.catalina.core.StandardEngine : Starting Servlet engine: [Apache Tomcat/10.1.24]2024-05-31T08:53:40.948+08:00 INFO 14832 --- [demo] [ main] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext2024-05-31T08:53:40.949+08:00 INFO 14832 --- [demo] [ main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 921 ms2024-05-31T08:53:41.257+08:00 INFO 14832 --- [demo] [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat started on port 8888 (http) with context path '/'2024-05-31T08:53:41.274+08:00 INFO 14832 --- [demo] [ main] com.example.demo.DemoApplication : Started DemoApplication in 1.702 seconds (process running for 2.143)
我們可以在日志 Started DemoApplication in 1.702 seconds 看到啟動耗時為 1.702 秒。
需要先 cd 到訓(xùn)練的 application 目錄。
$ java -XX:SharedArchiveFile=application.jsa -jar demo-0.0.1-SNAPSHOT.jar . ____ _ __ _ _ /// / ___'_ __ _ _(_)_ __ __ _ / / / /( ( )/___ | '_ | '_| | '_ // _` | / / / / /// ___)| |_)| | | | | || (_| | ) ) ) ) ' |____| .__|_| |_|_| |_/__, | / / / / =========|_|==============|___/=/_/_/_/ :: Spring Boot :: (v3.3.0)2024-05-31T08:53:15.828+08:00 INFO 21444 --- [demo] [ main] com.example.demo.DemoApplication : Starting DemoApplication v0.0.1-SNAPSHOT using Java 21.0.3 with PID 21444 (D:/test/demo/target/application/demo-0.0.1-SNAPSHOT.jar started by L.cm in D:/test/demo/target/application)2024-05-31T08:53:15.830+08:00 INFO 21444 --- [demo] [ main] com.example.demo.DemoApplication : No active profile set, falling back to 1 default profile: "default"2024-05-31T08:53:16.244+08:00 INFO 21444 --- [demo] [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat initialized with port 8888 (http)2024-05-31T08:53:16.249+08:00 INFO 21444 --- [demo] [ main] o.apache.catalina.core.StandardService : Starting service [Tomcat]2024-05-31T08:53:16.249+08:00 INFO 21444 --- [demo] [ main] o.apache.catalina.core.StandardEngine : Starting Servlet engine: [Apache Tomcat/10.1.24]2024-05-31T08:53:16.272+08:00 INFO 21444 --- [demo] [ main] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext2024-05-31T08:53:16.273+08:00 INFO 21444 --- [demo] [ main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 419 ms2024-05-31T08:53:16.425+08:00 INFO 21444 --- [demo] [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat started on port 8888 (http) with context path '/'2024-05-31T08:53:16.431+08:00 INFO 21444 --- [demo] [ main] com.example.demo.DemoApplication : Started DemoApplication in 0.722 seconds (process running for 0.885)
我們可以在日志 Started DemoApplication in 0.722 seconds 看到啟動耗時比直接啟動少了將近 1 秒。效果還是非常明顯的。
CDS、CRaC 和 GraalVM,這三種技術(shù)都有助于提高Java程序的啟動速度,但它們的應(yīng)用場景和優(yōu)化方式有所不同。CDS 通過共享類數(shù)據(jù)來加速啟動,CRaC 通過運行時優(yōu)化來提升性能,而 GraalVM 則通過 AOT 編譯來實現(xiàn)快速啟動和高效運行。作為開發(fā)者,我們可以根據(jù)具體需求選擇合適的技術(shù)來優(yōu)化 Java 程序的啟動時間。
本文鏈接:http://www.tebozhan.com/showinfo-26-92185-0.htmlSpring Boot 3.3.0 新特性| 使用 CDS 優(yōu)化啟動時間
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