500 Internal Server Error .Too many open files....

500 Internal Server Error . Client was getting following error while accessing the form application.

 The OC4J log file shows

formsweb: Servlet error  Or web: Servlet error

java.io.IOException: Too many open files

Cause
On Windows systems , there is a limit to the number of files that can be simultaneously opened : about 2000.
This limit applies to all the servlets running in the OC4J_BI_Forms : The forms Servlets and the Reports Servlets. 
Solution
To increase the parameter numprocs for the OC4J_BI_Forms : 

1. Edit the file ORACLE_HOME\opmn\conf\opmn.xml 

2. Locate the following lines :
....
process-type id="OC4J_BI_Forms" module-id="OC4J">
....
process-set id="default_island" numprocs="1"/>
/process-type>
.....


3. Replace :
numprocs="1"
by
numprocs="2"

4. Execute the command : 
$ORACLE_HOME/bin/opmnctl reload 
in order to reload the file opmn.xml

The modification will be taken into account the next time the OC4J_BI_Forms will be restarted.

When numprocs > 1 , several processes will be started for the OC4J OC4J_BI_Forms. It means that the requests will be "load-balanced" between the 2 processes.
So, the number of files opened will be divided by 2 (if numprocs=2) and the limit will no more be reached.