Memory leak with BufferedFile?

[Leon]

I'm writing a simple program which uses merge sort to sort very large text
files. I split the text file into several temporary files which are sorted and
merged together.

The trouble I'm having is that the BufferedFile class seems to have a memory
leak. The memory usage of the process slowly goes up until it throws an out of
memory exception. I can fix the memory leak by switching to the File class,
but that makes the program much slower.

Calling GC.collect() didn't help, and neither did explicitly deleting the
BufferedFile object.