environment

Windows 10 64bit

Java

> java --version
openjdk 11.0.3 2019-04-16
OpenJDK Runtime Environment AdoptOpenJDK (build 11.0.3+7)
OpenJDK 64-Bit Server VM AdoptOpenJDK (build 11.0.3+7, mixed mode)

Implementation for verification

`Folder structure`


> tree /f
├─build
│  └─classes
│     └─java
│         └─main
│                 Hoge.class
└─src
    └─main
        └─java
                Hoge.java

`Hoge.java`


class Hoge {
    public static void main(String... args) {
        System.out.println("Hello World");
    }
}

Prior to Java 9

When debugging a Java program with Eclipse, add the following spell to the startup options.


> java -Xdebug -Xrunjdwp:transport=dt_socket,server=y,address=8000,suspend=y -cp build\classes\java\main Hoge

Prior to Java 9, this allowed you to remotely connect the debugger with the 8000 port (you need to keep the port open, of course).

An error will occur if Java 9 or later

However, when I try to connect to a JVM started with this option remotely with a debugger in Java 9 or later, the following error occurs.

無題.png

In Java 9, you can no longer connect remotely if you do not specify a host

JDK 9 Release Notes | Notes and Changes

JDWP socket connector accept only local connections by default The JDWP socket connector has been changed to bind to localhost only if no ip address or hostname is specified on the agent command line. A hostname of asterisk (*) may be used to achieve the old behavior which is to bind the JDWP socket connector to all available interfaces; this is not secure and not recommended.

In Java 9, if you don't specify a host, it will automatically be bound to localhost, and it seems that you can no longer connect remotely.

You can still connect from any remote location by using *, such as ʻaddress = *: 8000`. (However, it seems that it is not recommended because it is not good for security [^ 1])

[^ 1]: It's a non-production environment at the time of connecting with the debugger, so I don't think you need to worry about it. e? Do you connect the production with a debugger? Ahh

* Try to connect by specifying

> java -Xdebug -Xrunjdwp:transport=dt_socket,server=y,address=*:8000,suspend=y -cp build\classes\java\main Hoge

無題.jpg

connected.

reference

--Debug the jvm running on a non-local machine with Eclipse --TIM Labs

Can't remotely debug on Java 9 Tomcat 9 in docker container - Stack Overflow

You also need to specify the host when debugging remotely with Java 9 or later