How to know the line of a bug in a spring generated bean ?

Question

Hello,

I've got a website build with Spring and jpa (by hibernate). I've got a bug and I don't know how to identify the line where the bug appears.

I can't debug it on my ide because it's a live version (all runs fine in local).

I've got log which says: o

rg.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)#012#011

at org.springframework.aop.framework.Cglib2AopProxy$DynamicAdvisedInterceptor.intercept(Cglib2AopProxy.java:625)#012#011

at com.mycompany.server.rpc.UserService$$EnhancerByCGLIB$$64ed2d4f.createAccount(<generated>)#012#011

at com.mycompany.server.rpc.ServiceRPCImpl.createAccount(ServiceRPCImpl.java:309)

My problem is the third line. As the UserService object is handled by Spring, it becomes a proxy and I can't know the line of the bug.

Do you know how to solve the problem ?

Thanks

Answer 1

I would say that not being able to reproduce this locally is a significant restraint. I would try to set up your local environment or a test server to reproduce the problem, using JMeter or other load test software to simulate load of concurrent user accesses. Once this is done, your tweak/compile/test cycle becomes a lot shorter, and you can make experimental changes without fear of disrupting service on your production server. It may seem like a lot of effort, but the work will pay dividends not just for this bug, but for bugs you may encounter in future.

It sounds like it could be a threading bug, especially since spring by default uses singleton scope. With that in mind, look into creating multithreaded integration tests for the service that is failing. Once you have reproduced the bug through load testing, you can verify that it's a threading bug by making your main service method synchronized, preventing concurrent use. If the bug disappears, it is most likely a concurrency bug.

As to finding the line of the bug - there is no line to look for since the code is generated. The best you can do is to add defensive checks in all beans that are being used in the advice around the UserService. (E.g. check for null values due to missing injections.) The init-method attribute on beans is useful for performing checks that the bean has been fully constructed and all required collaborators have been set.

Answer 2

If you cannot reproduce the issue in local environment, then may be it is environment / network related issue. I would first recreate the issue in test environment ( which is closer to production environment and not just own local machine ) to debug the bug.

You may also use Fiddler to debug network related issues for a live version.

Answer 3

Is it possible for you to change from cglib to jdk proxy? (Spring AOP proxy reference)

Basically: if you access your beans as interfaces, you can use jdk proxies (spring default mechanism), thereby leaving the underlying object intact and gaining access to line numbers in stack traces.