Godot version:
Godot 3.1.1.stable.official and Godot v3.1.2.devel.custom_build
OS/device including version:
Windows7
Issue description:
Only create a lot of array in GDscript, the memory can be freed.
Only create a lot of array in GDNative(cpp), the memory can be freed.
But create a lot of array and PoolByteArray, PoolStringArray and so on, the memory can not be freed. And If the memory used more than device, the project will memory leak and crash.

For now I use something like this:
# test array
func _on_Button2_pressed():
for i in range(10000):
var data = []
for j in range(1024):
data.push_back(j)
test.test_array(data)
pass # Replace with function body.
The project I tested
gdnative_test.zip