Method adjustNumberOfThreads

Engine/OutputSchedulerThread.cpp:1503–1549

#ifndef NATRON_PLAYBACK_USES_THREAD_POOL
void
OutputSchedulerThread::adjustNumberOfThreads(int* newNThreads,
                                             int *lastNThreads)
{
    ///////////
    /////If we were analysing the CPU activity, now set the appropriate number of threads to render.
    int optimalNThreads;

    ///How many parallel renders the user wants
    int userSettingParallelThreads = appPTR->getCurrentSettings()->getNumberOfParallelRenders();

    ///How many threads are running in the application
    int runningThreads = appPTR->getNRunningThreads() + QThreadPool::globalInstance()->activeThreadCount();

    ///How many current threads are used by THIS renderer
    int currentParallelRenders = getNRenderThreads();

    *lastNThreads = currentParallelRenders;

    if (userSettingParallelThreads == 0) {
        ///User wants it to be automatically computed, do a simple heuristic: launch as many parallel renders
        ///as there are cores
        optimalNThreads = appPTR->getHardwareIdealThreadCount();
    } else {
        optimalNThreads = userSettingParallelThreads;
    }
    optimalNThreads = std::max(1, optimalNThreads);


    if ( ( (runningThreads < optimalNThreads) && (currentParallelRenders < optimalNThreads) ) || (currentParallelRenders == 0) ) {
        ////////
        ///Launch 1 thread
        QMutexLocker l(&_imp->renderThreadsMutex);

        _imp->appendRunnable( createRunnable() );
        *newNThreads = currentParallelRenders +  1;
    } else if ( (runningThreads > optimalNThreads) && (currentParallelRenders > optimalNThreads) ) {
        ////////
        ///Stop 1 thread
        stopRenderThreads(1);
        *newNThreads = currentParallelRenders - 1;
    } else {
        /////////
        ///Keep the current count
        *newNThreads = std::max(1, currentParallelRenders);
    }
}

#endif // ifndef NATRON_PLAYBACK_USES_THREAD_POOL