Huge number of oracle processes and oracle is not releasing process

Problem Symptoms 

In the database there is huge number of Oracle database processes and within several hours the processes reached the max limit of PROCESSES parameter. No one then can connect to database and therefore it is needed to restart the Server or need to kill the oracle process from operating system.

Recent changes are the,
1)Enable DCD.
2)SQLNET.EXPIRE_TIME is set to 1 or more.

Cause of the Problem
This problem is specific with Oracle Database release 10.2.0.3 and on Windows Platform. It is due to the the DCD (dead connection detection) mechanism. The orphaned processes are not being cleaned up even though DCD is enabled and SQLNET.EXPIRE_TIME is set to 1 or more.

Also the number of processes exceeds too much than the number of sessions.

SQL> select count(*) from v$session;

COUNT(*)
----------
55

SQL> select count(*) from v$process;

COUNT(*)
----------
600

In this case, the orphaned resources are not released if only the client application is terminated. After only the client computer has been rebooted, the DCD releases those resources. For example, a Windows application is killed but Windows machine remains running, the probe packet may be received and discarded as if the connection is still active. As it currently stands, it appears that DCD detects dead client machines, but not dead client processes.

Solution of the Problem
1. Comment the SQLNET.EXPIRE_TIME parameter in your sqlnet.ora file.
2. Reboot the server. Server reboot is funny thing to solve the problem.
3. Set KeepAlive mechanism in Windows 2000/NT.
To do so,
- Start > Run > Regedit.exe
- In the Registry, navigate to:
HKEY_LOCAL_MACHINE/SYSTEM/CurrentControlSet/Services/Tcpip/Parameters

- Edit - Add value: KeepAliveTime (REG_DWORD)
Decimal -> 180000 (for example = 3 minutes)

- The parameter will not be present the first time you modify the parameter, so you will need to add it. The default value is 2 hours.
4. Watch to see if there are any check if orphaned SHAD processes that exist.