TransactionCoordinator instances (created & owned by the TransactionCoordinatorService) have member variables which take mutexes to mutate other variables. The CatalogAndScheduler wrapper type acquires these during join() which is also called in the destructor of the transaction coordinator's catalog instance. During that destructor path, there is a chain of mutexes that can recurse in some code paths, leading to deadlock.

1. https://github.com/mongodb/mongo/blob/master/src/mongo/db/s/transaction_coordinator.cpp#L689
2. https://github.com/mongodb/mongo/blob/master/src/mongo/db/s/transaction_coordinator.cpp#L460
3. https://github.com/mongodb/mongo/blob/master/src/mongo/db/s/transaction_coordinator_service.cpp#L440
4. https://github.com/mongodb/mongo/blob/master/src/mongo/db/s/transaction_coordinator_catalog.cpp#L272