DeprecationWarning: Calling an asynchronous function without callback is deprecated. – how to find where the “function:” is?

You can use either the --trace-deprecation or --throw-deprecation options.

For example:

node --trace-deprecation app.js

or:

node --throw-deprecation app.js

The first option will log a stack trace and the second will throw an error (which, if not caught, will also log a stack trace).

Also, 4346 is most likely the process ID.