Philipp Dallig

@zjffdu I want to try to solve the concurrent problem in pull request #4252 with a ReentrantReadWriteLock. This solution should also catch this pull request. Give me some time for...

I merged #4252 into master. Please rebase to the current master. I think this PR is still needed.

We should remove `slf4j-log4j12` completely and replace it with the slf4j-api in the zeppelin code. Instead of `log4j1` we should ship `log4j2`.

> @Reamer , greetings ! i am working on it to completely replace log4j with log4j2 and remove the usage of `slf4j-log4j12` please allow me sometime to fix the error...

@dependabot recreate

> Do you have any good Idea? Unfortunately not. > Or is there any way to modify the code of this PR? I am not aware of any possibility.

@dependabot rebase

@zjffdu Interesting PR. Any motivation to keep working on it?

Please provide an example (after, before). It seems that the Zeppelin server log4j configuration is also adjusted. There should not be the `Logging.scala` problem.

Thanks for the screenshots. I think that the line number `:57` is very confusing. We should remove the line number of `Logging.scala` as well. In addition, it seems that you...