Why viewport height doesnt match window.innerHeight?

[fsuarez]

Sometimes when changing the orientation of the device this values does not match and the screen gets shrinked, how can that happen? This issue is on android and happens on multiple devices from android 2 to 4.
Would be very helpfull if you can please explain me how the resizing works and how the viewport size gets updated. I have looked at the code and i dont get it

[mitchellsimoens]

The Viewport has 100% width and height set on it so it's up to the browser to handle resizing the viewport.

[fsuarez]

So is there any known workaround to handle this problem?