1 files changed, 44 insertions, 0 deletions
diff --git a/src/gui/kernel/qguiapplication.cpp b/src/gui/kernel/qguiapplication.cpp
index 2a5a4933907..1e44ac83361 100644
--- a/src/gui/kernel/qguiapplication.cpp
+++ b/src/gui/kernel/qguiapplication.cpp
@@ -99,6 +99,10 @@
 #include <private/qvulkandefaultinstance_p.h>
 #endif
 
+#if QT_CONFIG(thread)
+#include <QtCore/QThreadPool>
+#endif
+
 #include <qtgui_tracepoints_p.h>
 
 #include <private/qtools_p.h>
@@ -686,6 +690,20 @@ QGuiApplication::~QGuiApplication()
     d->cursor_list.clear();
 #endif
 
+#if QT_CONFIG(qtgui_threadpool)
+    // Synchronize and stop the gui thread pool threads.
+    QThreadPool *guiThreadPool = nullptr;
+    QT_TRY {
+        guiThreadPool = QGuiApplicationPrivate::qtGuiThreadPool();
+    } QT_CATCH (...) {
+        // swallow the exception, since destructors shouldn't throw
+    }
+    if (guiThreadPool) {
+        guiThreadPool->waitForDone();
+        delete guiThreadPool;
+    }
+#endif
+
     delete QGuiApplicationPrivate::app_icon;
     QGuiApplicationPrivate::app_icon = nullptr;
     delete QGuiApplicationPrivate::platform_name;
@@ -4553,6 +4571,32 @@ QInputDeviceManager *QGuiApplicationPrivate::inputDeviceManager()
 }
 
 /*!
+    Returns the QThreadPool instance for Qt Gui.
+    \internal
+*/
+QThreadPool *QGuiApplicationPrivate::qtGuiThreadPool()
+{
+#if QT_CONFIG(qtgui_threadpool)
+    Q_CONSTINIT static QPointer<QThreadPool> guiInstance;
+    Q_CONSTINIT static QBasicMutex theMutex;
+    const static bool runtime_disable = qEnvironmentVariableIsSet("QT_NO_GUI_THREADPOOL");
+    if (runtime_disable)
+        return nullptr;
+    const QMutexLocker locker(&theMutex);
+    if (guiInstance.isNull() && !QCoreApplication::closingDown()) {
+        guiInstance = new QThreadPool();
+        // Limit max thread to avoid too many parallel threads.
+        // We are not optimized for much more than 4 or 8 threads.
+        if (guiInstance && guiInstance->maxThreadCount() > 4)
+            guiInstance->setMaxThreadCount(qBound(4, guiInstance->maxThreadCount() / 2, 8));
+    }
+    return guiInstance;
+#else
+    return nullptr;
+#endif
+}
+
+/*!
     \fn template <typename QNativeInterface> QNativeInterface *QGuiApplication::nativeInterface() const
 
     Returns a native interface of the given type for the application.