TBB Learning

Control the number threads

• Method 1: Use the environment variable TBB_NUM_THREADS for the gloabl setting.

export TBB_NUM_THREADS=4

TODO: It doesn’t seem to work!

• Method 2: Use tbb::task_arena or tbb::task_scheduler_init (Deprecated).

TBB will use this setting locally within the scope of the tbb::task_arena.

#include <tbb/pipeline.h>
// Deprecated:
// #include <tbb/task_scheduler_init.h>
#include <tbb/task_arena.h>

// Define your pipeline body
class MyPipeline {
public:
    void operator() (tbb::flow_control& fc) const {
        // Your pipeline logic here
        // ...
        // Inform the pipeline that there is no more data
        fc.stop();
    }
};

int main() {
    // Deprecated: tbb::task_scheduler_init init(1);
    tbb::task_arena arena(4); // 4 threads
    // Do some tasks:
    tbb::parallel_pipeline(/* max_number_of_live_tokens */ 4, MyPipeline);

    return 0;
}