How can a process get a backtrace of its own stack?
a certain process.  Maybe you can change it for your needs.
I use this a cheap, simple, always available piece of metering code.
the way it scrolls when the stack gets large and then shrinks.
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(update-interval '(and number (satisfies plusp)) :default .5 :documentation "Number of seconds between updates"
be expensive because it often takes page faults.