OH questions:

-- test_and_set()? atomic<bool> guard.


How to wake cpu's? When another cpu is interrupted/managing threads.
Eg: # of running threads goes down to one, thebn a broadcast/signals wake
a bunch of threads.

-- How does a thread enter the ready queue?
Supposing mutex/cv has some internal data about blocked threads...
nvm.

What should a thread do when it finishes? What does it mean for a thread to execute
when the thread object is destroyed? By thread object, does the spec mean its context?

What does it mean to destroy a thread object?
Thread object is object of the thread class. Thread_impl* is a heap-allocated object.
We can destroy the thread object without deleting thread_impl, and vice versa. Want to
keep thread_impl around as long as the thread isn't done computing. On the other hand,
if there are references to the thread object (eg: t2 wants to join t1, even though t1
finished executing long ago), the object should remain in scope.


#include <unistd.h>
sleep(); // busy??