doc描述的比较清楚，看doc吧
SQL> select addr,program from v$process where pid=1;
ADDR PROGRAM
---------------- ---------------
043120010AE PSEUDO
SQL>
[@more@]The PSEUDO 'process' is responsible for interim 'ownership' of internal structures associated with a process such as when a process is killed.
The pseudo process is not a true process, per se. There is no associated session. It is as mechanism used internally to aid in the management of internal process structures such as in the situation I noted.
When a session is killed, the session state object(and all the child state objects under the session state object) move out from under the original parent process state object, and are placed under the pseudo process state object (which is expected, given the parent/child process mechanism on Unix). PMON will clean up all the state objects found under the pseudo process state object. That explains why PADDR changes in V$SESSION when a session is killed. New PADDR you are seeing in v$SESSION is the address of the pseudo process state object. This shows up in system state under PSEUDO PROCESS for group DEFAULT: V$PROCESS still maintains the record of the original
parent process.
来自 “ ITPUB博客 ” ，链接：https://blog.itpub.net/19602/viewspace-1044329/ ，如需转载，请注明出处，否则将追究法律责任。
