lots wait on BEGIN SYS.KUPW$WORKER.MAIN(

hi there,

I got this Oracle 11g on RHEL7.9.

impdp very slow, this wait is on top of "sql ordered by ela",

but the time is not include in the top 10 wait event.

I tried to search this "BEGIN SYS.KUPW$WORKER.MAIN('SYS_IMPORT_SCHEMA_01', 'SYSTEM', 0); END;"

but did not find any useful information.

And I tried to trace this sqlid with sqltrace.

alter system set timed_statistics=true;

alter system set max_dump_file_size=unlimited;

alter system set statistics_level=all;

alter system set events 'sql_trace[sql: 7nrhqb011sv5x] level=12';  -- replace the SQLID here