Are you kiding??? You do like this???? No testing environment? ALL UPDATES MUST BE TESTED IN NON PRODUCTIVE VERSION. YOU DIDn't know it???
Now I know, why all this bugs and delay cames.. you go blind in the dark and want to find a needle. "nice", dear Marin, Nice :D
I am a professional developer and deadlock (what Marin is describing) is normally a very difficult problem to deal with. Every time I have experienced it in the past, it is something that occurs only in production because it is impossible to recreate the same usage in the testing environment as what happens in the production environment. The root cause of deadlock is contention over the same resource (i.e. two components trying to use/update the same piece of data at the same time). Production has hundreds of people using it at the same time, and test does not and never will. Since you cannot recreate the problem in test, the only way you know if any attempt you made to fix the symptoms succeeds is to try a fix in production and see if the symptoms go away.
So while you joke about him being blind in the dark, he is trying to fix a problem that is difficult to recreate in a test environment without knowing the root cause and that he can't study in the one environment it fails in (production) because he needs to fix immediately. The hardest part of fixing a deadlock issue is finding the root cause, until that is identified any developer would be blind in the dark.