Change the number of nodes (internal and leaf).

[niuzhiheng]

It did not cause problem before the fix. It simply allocated more than what you need.

[pdollar]

actually, if the maxDepth=inf then the tree can have maximum number of nodes proportional to the amount of training data, hence the current setup. you are right tho, most of the time it's overkill. still, the memory usage is negligible, so i'm inclined to leave it as is.