In the current model, any hanging request actually delays the entire rendering. I agree with you and Ingo that this is a fragile with regards to the linters which may take long, but it could be addressed incrementally (e.g. make results rendering incremental without re-running all the linters). It should not be holding up this PR. This is already way better than nothing. *Existing* linters can take advantage of this. This is all started just because I wanted to support recursive configuration file look up in JSHint which can be done right now. I don't see this is piece of code as a step in an opposite direction.