TBB: Possible to get Thread IDs?

Question

I have a very simple parallel_for loop

    tbb::parallel_for(tbb::blocked_range<int>(0, values.size()),
    [&](tbb::blocked_range<int> r)
    {
        for (int i = r.begin(); i < r.end(); ++i)
        {
            values[i] = std::sin(i * 0.001);
        }
    });

Where 'values' is a vector of doubles. What I'd like to know is which threads work on which range in the loop. Is it possible to get a thread ID of some kind from TBB?

Cephalopod

shouldn't std::this_thread::get_id() just work? – Cruzcruzado

I don't think so, at least per this: software.intel.com/en-us/node/506336 – Cephalopod

Well, that what I was reading" Replacement -> std::thread means "std::thread::get_id() should behave as expected from wherever it is called." (software.intel.com/en-us/forums/intel-threading-building-blocks/…) – Cruzcruzado

Ah, I must’ve misread it, then. My apologies. – Cephalopod

If you're dealing with quite fresh TBB installation you could try to call it and see how it is going. If it works, just post it as your own answer, I would happily endorse it, it is useful to know that it is working solution. I don't have anything with TBB right now, couldn't test myself – Cruzcruzado

Answer 1

Also, if you want to know a relative number of worker thread in current task_arena, which goes from 0 to the arena concurrency level, use this:

int worker_index = tbb::task_arena::current_thread_index();

The range of index values can be contiguous if all the threads will get to work at the same time.

Dissymmetry

This is the solution I ended up using, the "IDs" make much more sense. – Cephalopod

This works well, also tbb::this_task_arena::max_concurrency() is useful in combination with current_thread_index to get the maximum number of threads that may run to setup per-thread storage – Phyllous

Answer 2

Looks like the solution is to use

tbb::this_tbb_thread::get_id()

in tbb_thread.h. See this for more details:

https://software.intel.com/en-us/node/506336

Cephalopod