caltechcs2 / concurrency Goto Github PK

We should update the following section of the assignment, since we use std::thread now.

And, I'm not sure if the "You cannot call a member function from a thread directly" comment is still true. If it isn't, perhaps we should remove this hint entirely.

Helpful hints

You cannot call a member function from a thread directly; if this is something you would like to do, you will need to wrap it in a non-class function first, like this:

class Foo
{
    Foo() { }
    ~Foo() { }

    void f() { /* Do something interesting here. */ }
};

void *f_wrapper(void *arg)
{
    Foo *fptr = (Foo *) arg;
    fptr->f();
}

Foo *f = new Foo();
Thread *t = new Thread();
t->run(f_wrapper, (void *) f);

Changes to assignment writeup as discussed in TA meeting 2016/2/19:

The make memcheck produces output that is tedious to interpret, and it is not very helpful because avoiding memory leaks in student-written code is not a big challenge in this section.

Instead, we should

• Provide make memcheck as an optional tool; students are still responsible for not leaking memory, but are not encouraged to use make memcheck
• Have students run raytracing in N threads instead of 2 threads (where N is a variable).
• We could consider adding analysis questions after the N threads task. Examples to consider:
  • "Run your code with different values of N, observe how performance scales on your machine, and provide 2 or more speculations about why it might scale this way." (1 point or 2 points; I want them to actually run it on their machines, but I don't want them to spend too much time writing up their speculations.)
  • "Suppose that it is much more computationally intensive to trace some rays that to trace other rays (for example, if some rays bounce of of many more objects than other rays). How might an approach similar to a producer-consumer queue provide a performance improvement over an approach that assigns an equal number of rays to each thread? Your answer need not exceed M sentences (where M is determined by a concise reference answer).

This should be done a week or two after the assignment is due (that is, ~Feb 23 - March 1)

As discussed in TA meeting 2016/2/19