QtQml: Clear stale compilation units more thoroughly

There are various places where we can still hold references. Clean them
up when asked to do so. Also, free unused types and caches outside the
type loader mutex, and only once on engine shutdown.

Change-Id: Iae77cd6f50ad847d29a7eae4ac5c7c1c2524065d
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

1 files changed, 10 insertions, 0 deletions

diff --git a/src/qml/qml/qqmlengine.cpp b/src/qml/qml/qqmlengine.cpp
index a5f6d4d531..b01c592316 100644
--- a/src/qml/qml/qqmlengine.cpp
+++ b/src/qml/qml/qqmlengine.cpp
@@ -623,9 +623,19 @@ QQmlEngine::~QQmlEngine()
 void QQmlEngine::clearComponentCache()
 {
     Q_D(QQmlEngine);
+
+    // Contexts can hold on to CUs but live on the JS heap.
+    // Use a non-incremental GC run to get rid of those.
+    QV4::MemoryManager *mm = handle()->memoryManager;
+    auto oldLimit = mm->gcStateMachine->timeLimit;
+    mm->setGCTimeLimit(-1);
+    mm->runGC();
+    mm->gcStateMachine->timeLimit = std::move(oldLimit);
+
     d->typeLoader.lock();
     d->typeLoader.clearCache();
     d->typeLoader.unlock();
+    QQmlMetaType::freeUnusedTypesAndCaches();
 }
 
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