Thread or not threads?

I have 4 columns in a table, id, sub_id, timestamp and value.
The primary key is id, sub_id and timestamp combine.
I need to insert many rows (may be 10 thousands every 4 minutes)
as fast as I can to the same host, same port, same database, same table.

A.
Open only one JDBC (Java Database Connective) connection,
have multiple threads (similar to UNIX child process) to do
the insert.
Note, too many threads will cause the system out of memory!

B.
Open only one JDBC connection, have only one single thread
to do the insert.

C.
Open multiple JDBC connections threads, each one of them
handle the data insert.

D.
Please tell me your way, the much better way.

Currently I am doing A. I have to limited the number of threads that
won't cause the system out of memory. But there is big bottleneck there.

The UNIX system scheduling can only do one insert a time (I think).
I am wonder choose C will be better? Tell me the D.
Thank you very much in advance!

P.S.
The database server is PostgreSQL 7.x. and the UNIX box is Redhat Linux
6.5.

--
Why we want to teach our babies to talk and walk,
then later we tell them "sit down!", "be quiet!" ?

Democracy is not a better way for a solution,
it is just another way to spread the blames.

--Raymond