Per Spring's documentation here, I added a shutdown hook:
SpringApplication app = new SpringApplication(App.class);
DefaultProfileUtil.addDefaultProfile(app);
appContext = app.run(args);
appContext.registerShutdownHook();
However the @PreDestroy method does not get called if the application is killed after starting.
import org.springframework.stereotype.Service;
import javax.annotation.PreDestroy;
import javax.annotation.PostConstruct;
@Service
public class Processor {
public Processor() {
...
}
@PostConstruct
public void init() {
System.err.println("processor started");
}
//not called reliably
@PreDestroy
public void shutdown() {
System.err.println("starting shutdown");
try {Thread.sleep(1000*10);} catch (InterruptedException e) {e.printStackTrace();}
System.err.println("shutdown completed properly");
}
}
All I ever see is processor started...
processor started
^C
If I wait at least 30 seconds for spring to complete starting up, and THEN kill the process, then the @PreDestroy annotated function does get called.
processor started
[...]
2018-12-26 17:01:09.050 INFO 31398 --- [ restartedMain] c.App : Started App in 67.555 seconds (JVM running for 69.338)
2018-12-26 17:01:09.111 INFO 31398 --- [ restartedMain] c.App :
----------------------------------------------------------
Application 'App' is running! Access URLs:
Local: http://localhost:8081
External: http://10.10.7.29:8081
Profile(s): [dev]
----------------------------------------------------------
2018-12-26 17:01:09.111 INFO 31398 --- [ restartedMain] c.app :
----------------------------------------------------------
^Cstarting shutdown
shutdown completed properly
How do I determine when it is safe to depend on the calling of all @PreDestroy annotated functions?
I know how to register a shutdown hook with the JVM and that is what I am currently doing, however it seems to me that @PreDestroy should be doing that.
By "safe to depend on" I am assuming a normal shutdown sequence (i.e. requested by SIGTERM or SIGINT) and not power outages and killing the process, etc.
