Setting shader effect for Map items cause huge memory usage and total system freeze

Recently after updating my application to Qt 5.13.0 (from 5.10), I see the total system freeze when zooming in out too fast, after lots comment and test, i figured out that setting layer.enabled: true for MapPolyLine item causes the problem, seems related to QTBUG-66840, i see lots of QOpenGLFramebufferObject: Framebuffer incomplete, missing attachment warnings in console.

I have 8Gb RAM, and when this happens, about 5Gb of RAM will be used by linux cache(finding  through vmstat) and after some playing, the linux cache eats all of available RAM and linux system will be freezed or OOM killer kills my application.

I figured up a simple workaround, which is placing map quick items in MapItemGroup and setting shader effect for map item group, untill now its not freezing system but huge memory will be used (my applications memory usage will bump to 3G from 400mb when the is layer.enabled: true)

To reproduce this bug, open planesplotter, and add following inside planesplotter.qml :

MapPolyLine

{     path: [berlin, london]     layer.enabled: true     layer.samples: 8 }

 

Zooming in out fast, will freeze your system!