Increasing memory when using multiple QQuickViews with multiple QQMLEngines

Our test example show a massive increase on used RAM when it's being executed in an overnight test (8h).

Test description (TestRamMin.zip):

• Simple test program creates one main window and one component window, using the same QML file containing a QTQuick-TextItem.
• Both initialized with their own QQmlEngine and their own QML-Context. The windows show the current value of an QTimer measuring the program execution time. As shown in test_program.png.

What we observed is, that if the two windows share the same QQmlEngine the memory consumption keeps nearly the same over a time-span of 8 hours, see memory_ok.png.

But, if the windows do not share the QQMLEngine, additionally memory is consumed overtime. Doubling in somehow regular lapses within the 8 hours test-frame, as shown in memory_increasing.png.

~40min, ~80min, ~150min, ~300min

Notes:

• Trace/Usage graph was created with heaptrack and heaptrack_gui
• Output shows that memory is mainly consumed by an instance of QArrayData
• If the second window (Display) is closed the memory is freed, which  means we are not dealing with an actual leak but with an over-consumption.