dbms_random in parallel

The documentation for dbms_random states:

It will automatically initialize with the date, user ID, and process ID if no explicit initialization is performed.

This phrase does not answer the question, which “process id” is going to be used for initialization in case of parallel execution. That’s why I decided to give a vivid example that shows independence of “dbms_random” generator from “process id” of slave, that is generating identical values in parallel:

with
 t  as ( select/*+ materialize */ level n from dual connect by level<=4000)
,t1 as (
         select--+ materialize parallel(t 4)
            dbms_random.string('x',4)
            ||';'
            ||(select sid||';'||process||';'||pid
               from v$session, v$process
               where sid=sys_context('USERENV','SID')
                 and PADDR=ADDR
                 and n>0
              ) f
         from t
)
,t2 as (
         select
            t1.f
           ,count(*) over(partition by regexp_substr(f,'^[^;]+')) cnt
         from t1
)
select f
      ,regexp_substr(f,'[^;]+') rnd
      ,regexp_substr(f,'[^;]+',1,2) sid
      ,regexp_substr(f,'[^;]+',1,3) process
      ,regexp_substr(f,'[^;]+',1,4) pid
from t2 
where cnt>1
order by f

Result: