Debugging an Asynchronous RFC in SAP ABAP

In SAP system, an Asynchronous call (aRFC) of a remote-enabled function module specified in func using the RFC interface. The addition DESTINATION is used to specify a single destination in dest or use IN GROUP to specify a group of application servers. The latter supports parallel processing of multiple function modules.

Check the below link which tells about Asynchronous RFC:

https://help.sap.com/http.svc/rc/abapdocu_751_index_htm/7.51/en-US/abapcall_function_starting.htm#!ABAP_ADDITION_2@2@