Threads, when to use and why?

[SecretShop]

Heres a question, when writing a few programs I have been presented with the choice to use or not use threads.  Every time I usually choose not to and just multi-plex with some async calls.  Under what circumstances is it better or worse to use threads and why? What do you guys think?

[Yoni]

On multiprocessor systems, if you run 1 thread per CPU, you utilize all CPUs.

[MyndFyre]

Heres a question, when writing a few programs I have been presented with the choice to use or not use threads.  Every time I usually choose not to and just multi-plex with some async calls.  Under what circumstances is it better or worse to use threads and why? What do you guys think?

When you need to do a background task and not interrupt the GUI.  (This is common for print spooling or listening for data over the network).

[Banana fanna fo fanna]

Use non-blocking calls whenever possible (i.e. I/O) and IPC or threads when you need.

OT: does anyone know a Scheme implementation with nonblocking I/O?

[Yegg]

OT: does anyone know a Scheme implementation with nonblocking I/O?

Depending on what you're intersted in, have you tried CHICKEN? If you don't already know about it, it can easily interface with C.