Reproduction of hanging on rollback when a write idle timeout has not been configured for PostgreSQL connections, and the server closes the connection.
Run main in HangOnCloseApp.kt to reproduce the behavior. The point where it hangs is on line 81 of that same file, and the idle timeout can be enabled by uncommenting line 39.
Not setting a write idle timeout results in the IdleStateHandler of Netty (a copy of which is included here), to not unvoid the promise passed to ctx.write(...) in IdleStateHandler.write. Leaving all idle timeouts as 0, forcing NetClientImpl to always add an IdleStateHandler (see line 100 of NetClientImpl), and always unvoiding the promise (see line 305 of IdleStateHandler), will also resolve the issue.