http://www.ussg.iu.edu/hypermail/linux/kernel/0508.1/0106.html

this patch tracks things like poll/select as well which is a lot more useful for the specific use case of finding gtk applications that schedule timers to run more often.

A minor god, to be sure — somewhere between Pellor and Mnemosyne, I’d say — but still quite bodacious.

I have a question though. I wrote a peace of code for gnuplot where I have to care about stdin from the command-line interface and at the same time to look for the GUI events (clicks, moves, keys) coming from the ‘plot’ window. The main thread is a loop on a function called waitforinput() which is supposed to return the next character from stdin while processing the GUI events when they arrive. There is a second thread which is a usual GUI loop, and when it processes an event, it forwards it to the main one using a mutex’ed list. I ended up using select() on stdin with a timeout to periodically check for the contents of this list. So gnuplot falls in your category of “bad programs”, but it’s because I don’t know how else to do ! Do you have an idea ?

Toolkits like GTK will let you register a fd watch (like for stdin).

Otherwise, you can get the X socket fd from the display using the ConnectionNumber() call and add it to your stdin mainloop that way (this is what GDK does internally).