Oracle Database Discussions

i am unable to login to the database , getting
error "ORA-00020: maximum number of processes (%s) exceeded"
i did ps -ef|grep LOCAL=NO and found around 400 connections.
After i killed some of them i was able to login. But this keeps happening.
How can i find the parent process of these sessions?
i think these are dedicated process for each database session, bt how can i deal
with these increasing sessions
I took the spid and checked for their existence in the database bt they dont seem
to be logged into the db.

Thankyou