Surprising and dangerous Spring shutdown behaviour

Just by chance I noticed that one of my beans were being closed twice when the Spring context was closed down. It turns out that Spring is, by default actively looking for some way to close down all beans during shutdown. It’ll actually fall back to invoking a method called “close” if nothing else has been configured!

While this might sound like a feature and even a good idea, I don’t trust Spring to figure out a safe order to close down thread pools, executors, clients and other resources with a life cycle! It’s probably not a good idea to close down the database connection before the executor service that’s currently processing remaining tasks from a queue..

package com.developerb.spring;

import org.junit.Test;
import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;

import static junit.framework.TestCase.assertFalse;

/**
 * Unit test demonstrating surprising and dangerous behaviour
 * when shutting down a Spring Application Context. It turns out
 * that Spring will, by default invoke a method named "close"
 * during shutdown.
 * 
 * @author Kim A. Betti <kim@developer-b.com>
 */
public class BugOfDestructionTest {

    @Test
    public void experimental() {
        AnnotationConfigApplicationContext context = createContext();
        RandomClient client = getClientFromContext(context);
        context.close();

        // This should not happen!!
        assertThatTheCloseMethodHasNotBeenInvoked(client);
    }

    private AnnotationConfigApplicationContext createContext() {
        AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext();
        context.register(TestConfiguration.class);
        context.refresh();
        return context;
    }

    private RandomClient getClientFromContext(AnnotationConfigApplicationContext context) {
        RandomClient client = context.getBean(RandomClient.class);
        assertThatTheCloseMethodHasNotBeenInvoked(client);

        return client;
    }

    private void assertThatTheCloseMethodHasNotBeenInvoked(RandomClient client) {
        assertFalse("Spring has invoked the close method!", client.hasBeenClosed);
    }


    @Configuration
    static class TestConfiguration {

        @Bean
        RandomClient client() {
            return new RandomClient();
        }
    }

    static class RandomClient {
        public boolean hasBeenClosed = false;

        public void close() {
            hasBeenClosed = true;
        }
    }

}

This problem seems to be originating in Spring’s DisposableBeanAdapter.

Bug or feature?