Intelij IDEA 2022.1 无法调试 Runtime.getRuntime().addShutdownHook();

Question

I've tried to debug Runtime.getRuntime().addShutdownHook(unfortunateHook); in sample tapestry application created with Maven quickstart, but it seems that it doesn't work - Debugger doesn't stop at trap set to line set at LOGGER.debug("In the main hook!!!");

Example code:

package org.example.spring;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.boot.builder.SpringApplicationBuilder;
import org.springframework.boot.web.servlet.support.SpringBootServletInitializer;

@SpringBootApplication
public class App extends SpringBootServletInitializer {

    private static final Logger LOGGER= LoggerFactory.getLogger(App.class);

    @Override
    protected SpringApplicationBuilder configure(SpringApplicationBuilder application) {
        return application.sources(AppConfiguration.class);
    }

    public static void main(String[] args) throws Exception {
        Thread unfortunateHook = new Thread(() -> {
            LOGGER.debug("In the main hook!!!");
            try
            {
                Thread.sleep(5000);
            }
            catch (InterruptedException e)
            {
                throw new RuntimeException(e);
            }
        });
        Runtime.getRuntime().addShutdownHook(unfortunateHook);
        LOGGER.debug("Simple log statement with inputs {}, {} and {}", 1,2,3);

        SpringApplication application = new SpringApplication(App.class);
        SpringApplication.run(App.class, args);
    }
}

Is it possible to debug code inside shutdown hook thread? I'm using InteliJ Idea 2022.01. Killing application with standard Intelij Idea way (red square).

Answer 1

Ok, after some more digging I have found this: https://youtrack.jetbrains.com/issue/IDEA-170313/Breakpoints-not-working-after-stop-signal and many more simmilar threads.

In short, Idea is disconnecting debugger in a moment that you click red square and sends signal to app to kill itself. Because of these, traps are not working any more.

Workaround to this is to send kill signal from external source. In Linux it's pretty easy but in windows (which is I'm using) you should:

1. Put a break point any place in your code that will be executed
2. When code stops at your trap, you go to "evaulate expression" (alt+f8 or from degug acctions) and write System.exit(0)
3. You breakpoint may need to be set up as a thread one - to do that, click right button on it and switch to "Thread"

Then breakpoint should work.