Styjun

I have a spring boot app which creates a thread that monitors idle time before calling SpringApplication.exit() to terminate the app on being idle for a long time.. And i have a restcontroller class which serves web requests..

The issue is that even after SpringApplication.exit() is called, the controller seems to accept the incoming connections for a small window of time before the app itself exits. And this results in the client abruptly being terminated, when a new incoming connection is accepted by controller and then the earlier call to SpringApplication.exit() takes effect and makes the app exit.

//pseudo-code

@RestController
public class AppController 

 @PostMapping("/testproc")
 public ExitStatus process(@RequestBody Job testJob) 
 logger.info("Job batch Id passed: ", testJob.batchId);
 //do processing
 if(shutdownFlag) 
 //report error to client
 else 
 //do regular processing
 
 


@SpringBootApplication
public class MyApplication 

 public static void main(String[] args) 
 ctx = SpringApplication.run(MyApplication.class, args);
 Thread shutdownThread = new Thread(new Runnable() 
 //check for some condition
 if(shutdownFlag) 
 logger.info("Exiting");
 SpringApplication.exit(ctx, () -> 0);
 return;
 
 );

 shutdownThread.start();
 

logs generated:

2019-03-23 02:02:46.439 INFO 13484 --- [ Thread-10] c.i.e.newgenv1.svc.MyApplication : Exiting
2019-03-23 02:02:46.441 INFO 13484 --- [ Thread-10] ConfigServletWebServerApplicationContext : Closing org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@6660a289: startup date [Sat Mar 23 02:02:29 IST 2019]; root of context hierarchy
2019-03-23 02:02:46.509 INFO 13484 --- [nio-8081-exec-2] o.s.web.servlet.DispatcherServlet : FrameworkServlet 'dispatcherServlet': initialization started
2019-03-23 02:02:46.665 INFO 13484 --- [nio-8081-exec-2] o.s.web.servlet.DispatcherServlet : FrameworkServlet 'dispatcherServlet': initialization completed in 156 ms
2019-03-23 02:02:47.559 INFO 13484 --- [nio-8081-exec-2] c.i.etl.newgenv1.svc.AppController : Job batch Id passed: 23
2019-03-23 02:02:53.828 INFO 13484 --- [ Thread-10] o.s.j.e.a.AnnotationMBeanExporter : Unregistering JMX-exposed beans on shutdown

Pls note the lines logged.. The line "Exiting" generated by shutdown thread happens before Controller picks up a connection and prints batch id

I either need to stop the controller from picking up new connections or report an error code to the client during these times. But the issue is that controller picks up the connection but before it could report error, the app exits..

I even tried graceful shutdown logic outlined here: https://dzone.com/articles/graceful-shutdown-spring-boot-applications

but still it doesnt help..

You can add an interceptor which will check if shutdown is initiated. If not, the flow will continue it's normal execution else the requests should be dropped and proper response should be sent.