user_id 0 in V$ACTIVE_SESSION_HISTORY/DBA_HIST_ACTIVE_SESS_HISTORY

I noticed that some records in the active session history views report user_id = 0 (sys) and machine indicating remote clients which I'm sure are not using sys user to connect to the database. In my case the TOP_LEVEL_CALL_NAMEs are LOGOFF, OAUTH, VERSION2, ROLLBACK, Transaction Commit/Rollback.

I suppose these are some internal clean up operations, but I don't understand why some of them are associated with remote clients and others with the database server.

Does anybody know why this might be happening?

Thanks!

Regards
Dimitre

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