It's not clear what your question is. I am assuming you are not specifying 12,000 variables to be held in registers. Are you only asking how to do a random sort on a 12,000 variable vector?
It's equivalent to generating 12,000 order statistics. There is an algorithm in James Gentle's book that you can use for sequential generation of order statistics.
Below is a link to the errata of the book along with the name of the book.
http://mason.gmu.edu/~jgentle/books/rngbk/rng2errata.htm[
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