The process of solving a bug at work

problem ： Use grpc Null pointer crash caused by null listener when calling interface returns

To solve the process ： At first, I wanted to find out where to call grpc Interface passed in an empty callback , But there are too many interfaces , It's hard to find , No key information can be found from the log , Later, I want to replace grpc The underlying method , Add try catch, To this end, I also tried to use aspectjx, The experiment succeeded , But introduce aspectjx As a result, the package increases by nearly 4M, It's hard for me to accept , And the introduction of such a huge library is just to avoid the crash , Is not a good solution , Later, I gave up this plan , And I thought , Or find out where in the project null Well （ I went there for a while GitHub Upper grpc Source code issue I've seen it in the library , No one asked this question , So I think it's our own use , I also wondered if the listener object was recycled , Later, it was verified that , Also ruled out this possibility ）, Finally, I had a whim , Go with regularity as Can I search ？ Do as you say , I didn't find it at first , Later, I adjusted it several times , Finally, I found a code , Listener incoming null, It is an interface to update the location when the location changes , Then I hurried to experiment , Found no collapse ,what？ Later, I kept testing , At last it's back bugly On the problem , That is, the request interface will crash again after the network is disconnected , Finally found , However, if you interrupt to see whether there is a network or not, you will go to the bottom of the process try catch in , But the test result is that a network crash will be catch live , Without the Internet, it will collapse , Ah , I don't understand the underlying logic