Using QNetworkAccessManager across dll - qt

Question

I have a Qt5 application which uses QNetworkAccessManager for network requests which is accessible via a singleton and QPluginLoader to load extensions which add the functionality to the program. Currently I'm using static linking for plugins and everything works just fine.
However I want to switch to using dynamic libraries to separate the core functionality from other parts of the app. I've added the necessary declspec's via macro, and made necessary adjustments in my .pro files.
The problem is that very often (like, 3 of 4 starts) QNetworkAccessManager when used from dlls just returns an empty request or a null pointer. No data, no error string, no headers.
This is the code I'm using for loading plugins:
template <typename PluginType>
static QList<PluginType*> loadModules() {
QList<PluginType*> loadedModules;
foreach (QObject* instance, QPluginLoader::staticInstances()) {
PluginType* plugin = qobject_cast<PluginType*>(instance);
if (plugin) {
loadedModules << plugin;
}
}
QDir modulesDir(qApp->applicationDirPath() + "/modules");
foreach (QString fileName, modulesDir.entryList(QDir::Files)) {
QPluginLoader loader(modulesDir.absoluteFilePath(fileName));
QObject *instance = loader.instance();
PluginType* plugin = qobject_cast<PluginType*>(instance);
if (plugin) {
loadedModules << plugin;
}
}
return loadedModules;
}
Which is used in this non-static non-template overload called during the startup:
bool AppController::loadModules() {
m_window = new AppWindow();
/* some unimportant connection and splashscreen updating */
QList <ModuleInterface*> loadedModules = loadModules<ModuleInterface>();
foreach (ModuleInterface* module, loadedModules) {
m_splash->showMessage(tr("Initializing module: %1").arg(module->getModuleName()),
Qt::AlignBottom | Qt::AlignRight, Qt::white);
module->preinit();
QApplication::processEvents();
// [1]
ControllerInterface *controller = module->getMainController();
m_window->addModule(module->getModuleName(),
QIcon(module->getIconPath()),
controller->primaryWidget(),
controller->settingsWidget());
m_moduleControllers << controller;
}
m_window->addGeneralSettings((new GeneralSettingsController(m_window))->settingsWidget());
m_window->enableSettings();
/* restoring window geometry & showing it */
return true;
}
However, if I insert QThread::sleep(1); into the line marked 1, it works okay, but the loading slows down and I highly doubt it is a stable solution that will work everywhere.
Also, the site I'm sending requests to is MyAnimeList.

Answer 1

All right, now I have finally debugged it. Turned out I deleted internal QNetworkAccessManager in one of the classes that needed unsync access. That, and updating to Qt5.3 seem to have solved my problem.