Coin initial design was based on micro-services. The design didn't survived (IPC costs) and slowly, on python side we were moving to event loop based approach: asyncio. The shift was case by case, whenever we thought it is possible or easy to use async code. Sadly that incremental development caused some fragmentation, we use many threads to call blocking functions and in addition testing async code was considered harder. To be able to maintain the code this needs to be cleanup, otherwise debugging things like QTQAINFRA-1779 is just hard.