[chrisseaton]

Threads weren't very usable on most systems until around 2001? No, I don't know where you've got that idea from but it's not the case.

Java had threads in 1996. The Windows 32 API had threads from at least Windows 95. Windows NT had them since 1993. I don't know when Linux got threads and couldn't find anything, but I would presume it was the mid 90s at the very latest. In fact I don't think any of these threading APIs will have even changed much since the mid 90s. They weren't new ideas at the time either!

Look at this thread programming manual from 1994 which on page 3 lists five benefits of using threads at the time, only one of which is utilising the relatively rare multiprocessors. http://www4.ncsu.edu/~rhee/clas/csc495j/MultithreadedProgram...

[kibibu]

Linux got threads in 1996 when kernel 2.0 introduced the "clone" syscall, allowing multiple processes to share address space. LinuxThreads was built on top of this to implement the pthreads api.