[Quetion] How to set the size of the memory occupied by mapnik?

[JaylanChen]

When creating an mapnik instance and rendering a tile image (with a lot of geometric data), it takes a portion of the memory (positively associated with the volume of the data).

After the picture rendering is finished, the memory is still occupied; mapnik After the instance is destroyed, the memory is still occupied;
And the memory growth is not controlled by the memory settings of the node service (max_old_space_size).

How should I set the max memory limit of mapnik or make the mapnik memory use effectively?