Implementing 2 different transactions in a PL/Perl function

Hi,

How can I have two different transactions is a plperlu function?
My purpose is as follows:-

Transaction 1 does some series of inserts in tbl_abc
Transaction 2 updates some columns in tbl_abc fetching records from some other table.

I basically want 2 independent transactions in my function so that 1 commits as soon as it is done and 2 doesn't
depend on it at all.

Thanks,
~Jas