Multi-threaded sorting of text file

[MGW via Digitalmars-d-learn]

Need help:
There' s a large text file (hundreds of thousands of lines).
The structure is as follows:
2345|wedwededwedwedwe ......
872625|rfrferwewweww .....
23|rergrferfefer ....
................
It is necessary to sort this file by the first field having 
received:
23|rergrferfefer.......
2345|wedwededwedwedwe.......
872625|rfrferwewweww.......

There are also N CPU (from 4 to 8) and 16 Gb of Memory. Necessary
come up with an algorithm in D for fast sorting using 
multithreading.