#include <QCoreApplication>
#include <QtConcurrent>
#include <QMutex>
#include <map>

static QMutex               s_threadAccessMutex;
static std::map<void*, int> s_threadAccessCount;


static void runThread(int number)
{
    auto threadId = QThread::currentThreadId();
  //  qDebug() << number << " from thread " << threadId;

    QMutexLocker lock(&s_threadAccessMutex);
    ++s_threadAccessCount[ threadId ];
}


int main(int argc, char *argv[])
{
    int numObjects = QThread::idealThreadCount() * 10000;
    std::vector<int> items(numObjects);
    for (int i=0; i<numObjects; ++i)
      items[i] = i;

    QtConcurrent::blockingMap(items, runThread);

    int sum=0;
    int counter=0;
    for (const auto& it : s_threadAccessCount)
    {
        QString str;
        str.sprintf("Thread %2d: %5d hits", ++counter, it.second);
        qDebug() << qPrintable(str);
        sum += it.second;
    }
    qDebug() << "Sum: " << sum;
    qDebug() << "idealThreadCount() :" << QThread::idealThreadCount();
    qDebug() << "maxThreadCount()   :" << QThreadPool::globalInstance()->maxThreadCount();
    qDebug() << "actual Thread count:" << counter;

    return 0;
}