springboot 远程debug
应用：本地打断点，对运行在远程服务器上的程序进行调试
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远程调试
原理：本地jvm程序与远程jvm程序代码保持一致，通过调试协议进行通信
attach 模式：远程服务器暴露端口、开启监听，本地连接远程服务器
listen 模式：本地暴露端口、开启监听，远程应用连接到本地
-Xdebug：开启远程调试
jwdp参数，格式：
-Xrunjwdp:name=value,name2=value2,...
-agentlib:jwdp:name=value,name2=value2,...
jwdp name可选值：
transport：远程debug程序连接方式，dt_socket（默认）、dt_shmem（共享内存）
server：y（debug服务端）、n（默认，debug客户端）
address：server=n时必须设置；server=y时，可不设置
launch：jwdp初始化完成后，启动指定的程序（可选）
onthrow：指定异常发生后，开始jwdp的初始化（可选）
onuncaught：y（未捕获的异常发生后，开始jwdp的初始化）（可选）
n（默认，jwdp正常初始化）
stdalloc：n（默认值），可选
By default, the JDWP reference implementation uses an alternate allocator for its memory allocation.
If “y”, the standard C runtime library allocator will be used. This option is mainly for testing; use it with care.
Deadlocks can occur in this VM if the alternative allocator is disabled
strict：n（默认值），可选
If “y”, assume strict JVMDI conformance. This will disable all workarounds to known bugs in JVMDI implementations.
This option is mainly for testing and should be used with care.
suspend：y（默认值），可选
debug服务端是否等待debug客户端连接上后再启动，y：挂起等待、n：直接启动
If “y”, VMStartEvent has a suspend Policy of SUSPEND_ALL.
If “n”, VMStartEvent has a suspend policy of SUSPEND_NONE
debug服务端参数
jdk5及以后：-agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=*:5005
jdk4：-Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=5005
jdk3及之前：-Xnoagent -Djava.compiler=NONE -Xdebug -Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=5005debug客户端只需要连接服务端的ip:port（5005）即可进行调试
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示例
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controller 层
HelloController
@RestController
public class HelloController {
@RequestMapping("/hello")
public String hello(){
int i=1;
i+=1;
System.out.println(i);
return "hello";
}
}
项目打包：demo.jar
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attach 模式
demo.jar上传到远程服务器：suspend=n
[root@centos test3]# java -jar -agentlib:jdwp=transport=dt_socket,server=y,suspend=n,address=\*:5005 demo.jar
Listening for transport dt_socket at address: 5005
# 远程服务器开启监听端口：5005
# suspend=n，debug服务端不需要等待客户端连接就可以启动
. ____ _ __ _ _
/\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
\\/ ___)| |_)| | | | | || (_| | ) ) ) )
' |____| .__|_| |_|_| |_\__, | / / / /
=========|_|==============|___/=/_/_/_/
:: Spring Boot :: (v2.5.4)
2021-09-07 20:57:06.135 INFO 7603 --- [ main] com.example.demo.DemoApplication : Starting DemoApplication v0.0.1-SNAPSHOT using Java 16.0.2 on centos with PID 7603 (/usr/java/test3/demo.jar started by root in /usr/java/test3)
2021-09-07 20:57:06.152 INFO 7603 --- [ main] com.example.demo.DemoApplication : No active profile set, falling back to default profiles: default
2021-09-07 20:57:09.843 INFO 7603 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat initialized with port(s): 8080 (http)
2021-09-07 20:57:09.908 INFO 7603 --- [ main] o.apache.catalina.core.StandardService : Starting service [Tomcat]
2021-09-07 20:57:09.909 INFO 7603 --- [ main] org.apache.catalina.core.StandardEngine : Starting Servlet engine: [Apache Tomcat/9.0.52]
2021-09-07 20:57:10.256 INFO 7603 --- [ main] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext
2021-09-07 20:57:10.256 INFO 7603 --- [ main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 3745 ms
2021-09-07 20:57:12.248 INFO 7603 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat started on port(s): 8080 (http) with context path ''
2021-09-07 20:57:12.299 INFO 7603 --- [ main] com.example.demo.DemoApplication : Started DemoApplication in 8.387 seconds (JVM running for 12.667)
远程服务端：suspend=y
[root@centos test3]# java -jar -agentlib:jdwp=transport=dt_socket,server=y,suspend=y,address=\*:5005 demo.jar
Listening for transport dt_socket at address: 5005
# suspend=y：远程服务端开启监听端口，一直处于监听状态，直到debug客户端连接后才会启动
debug客户端：run ==> edit configuration ==> remote jvm debug
设置host、port
点击debug
debug服务端连接成功
本地打断点
发送请求：192.168.57.120:8080/hello
本地代码进入断点
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listen 模式
先开启本地debug（listen模式）
点击debug
demo.jar上传到远程服务器，启动
[root@centos test3]# java -jar -agentlib:jdwp=transport=dt_socket,server=n,address=******:5005,suspend=y demo.jar
******：本地服务器ip
server=n：表示远程服务器为debug客户端
server=n时，suspend=y、n启动效果等同
. ____ _ __ _ _
/\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
\\/ ___)| |_)| | | | | || (_| | ) ) ) )
' |____| .__|_| |_|_| |_\__, | / / / /
=========|_|==============|___/=/_/_/_/
:: Spring Boot :: (v2.5.4)
2021-09-07 21:28:16.162 INFO 7868 --- [ main] com.example.demo.DemoApplication : Starting DemoApplication v0.0.1-SNAPSHOT using Java 16.0.2 on centos with PID 7868 (/usr/java/test3/demo.jar started by root in /usr/java/test3)
2021-09-07 21:28:16.164 INFO 7868 --- [ main] com.example.demo.DemoApplication : No active profile set, falling back to default profiles: default
2021-09-07 21:28:18.888 INFO 7868 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat initialized with port(s): 8080 (http)
2021-09-07 21:28:18.920 INFO 7868 --- [ main] o.apache.catalina.core.StandardService : Starting service [Tomcat]
2021-09-07 21:28:18.921 INFO 7868 --- [ main] org.apache.catalina.core.StandardEngine : Starting Servlet engine: [Apache Tomcat/9.0.52]
2021-09-07 21:28:19.163 INFO 7868 --- [ main] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext
2021-09-07 21:28:19.163 INFO 7868 --- [ main] w.s.c.ServletWebServerApplicationContext : Root WebApplicationContext: initialization completed in 2878 ms
2021-09-07 21:28:20.941 INFO 7868 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat started on port(s): 8080 (http) with context path ''
2021-09-07 21:28:20.967 INFO 7868 --- [ main] com.example.demo.DemoApplication : Started DemoApplication in 6.044 seconds (JVM running for 7.015)
远程debug客户端启动后，debug连接建立
本地打断点，发送请求：192.168.57.120:8080/hello
listen模式重新debug，需要重启远程应用，attach模式不需要