Processes Remain In V$Process Without A Related Session

A query against the views V$SESSION and v$PROCESS may show different results. 
Many processes in the view V$PROCESS may exist without having a related session in the view V$SESSION , so that 
V$SESSION has much less entries compared to V$PROCESS . 
At the O/S level, there are numerous processes being generated with a LOCAL=NO description . 


The error ora-00020: maximum number of processes <num> exceeded 
might be seen for new connections. 


This can be from to causes:


1. An application is trying to connect to database with incorrect username /password
2. bug 5557660 which affects db until version 10.2.0.3


When using OCI connection pooling which keeps connecting / disconnecting 
it is possible to leak process groups which eventually leads to ORA-20 
and failure to allow any further logins.