Tuning QtConcurrent::map()

[Cruz]

Hi there,

I am experimenting with the QtConcurrent framework in order to launch multiple, long running threads that compute some scientific stuff.
I use a blocking QtConcurrent::blockingMap call with a member function like so:

void Experimenter::runExperiments()
{
   QtConcurrent::blockingMap(cases, [this] (ExperimentConfig& ex) { processCase(ex); });
}
 
void Experimenter::processCase(ExperimentConfig& ex)
{
    // compute many things
}

void Experimenter::runExperiments()
{
   QtConcurrent::blockingMap(cases, [this] (ExperimentConfig& ex) { processCase(ex); });
}

void Experimenter::processCase(ExperimentConfig& ex)
{
    // compute many things
}

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This works fine as it launches some 20 threads on my machine, but only one of these threads is actively working. I'm observing the threads in htop and I can see that only one core and one process is peaked to near 100%. The machine has plenty of memory available and barely 10% of it is used. Any ideas as to how I can make this more efficient?