Minimal program to reproduce hanging qt apps

activityNotifier.h

#ifndef ACTIVITY_NOTIFIER_H
#define ACTIVITY_NOTIFIER_H

void setIsActive(bool);

#endif

activityNotifier.mm

#include "activityNotifier.h"

#include <Foundation/NSProcessInfo.h>


static id activity = nullptr;

void setIsActive(bool active) {
    if (active && !activity) {
        activity = [[NSProcessInfo processInfo] beginActivityWithOptions: NSActivityUserInitiatedAllowingIdleSystemSleep reason:@"Disable napping"];
        [activity retain];
    } else if (!active && activity) {
        [[NSProcessInfo processInfo] endActivity: activity];
        [activity release];
        activity = nullptr;
    }
}

main.cpp

#include <QGuiApplication>

#include <QElapsedTimer>
#include <QTimer>

#include "activityNotifier.h"


int main(int argc, char *argv[])
{
    static bool detectedNap = false;
    static QElapsedTimer elapsedTimer;
    QGuiApplication a(argc, argv);
    QObject::connect(&a, &QGuiApplication::applicationStateChanged, [](Qt::ApplicationState state){
        qDebug("At %llds: App state: %d", elapsedTimer.elapsed() / 1000, state);
        detectedNap = false;
    });

    QTimer spamTimer;
    spamTimer.setInterval(1);

    elapsedTimer.start();
    static auto last = elapsedTimer.elapsed();

    QObject::connect(&spamTimer, &QTimer::timeout, &a, []{
        auto n = elapsedTimer.elapsed();
        if ((n - last) > 5000 && !detectedNap) {
            qInfo("At %llds: Napped", last / 1000);
            detectedNap = true;
        }
        last = n;
    });

    static bool disablerActive = false;
    static size_t interval = 45000;
    static QTimer napToggler;
    napToggler.setInterval(interval);

    QObject::connect(&napToggler, &QTimer::timeout, &a, []{
        setIsActive(disablerActive = !disablerActive);
        qDebug("At %llds: Nap disabler state: %d", elapsedTimer.elapsed() / 1000, disablerActive);
        napToggler.start(disablerActive ? interval *= 2 : 45000);
        detectedNap = false;
    });

    spamTimer.start();
    napToggler.start();

    return a.exec();
}

timer-test.pro

TARGET = timer-test

QT += widgets

CONFIG += c++11

TEMPLATE = app

LIBS += -framework Foundation

SOURCES += main.cpp

OBJECTIVE_SOURCES += activityNotifier.mm