This is because the garbage collector is rarely being activated.
These closures must not be moved by the garbage collector.
The result of all this is that the garbage collector reclaims redundant update frames.
We achieve this by allocating control flow compiled code on the heap, and extending the heap garbage collector to support this new data structure.
A concurrent garbage collector might have trouble finding all these pointers quickly.
The update routine must then be careful to save any pointers being returned in registers into a place where the garbage collector will find them.
Deallocation is done by the garbage collector once for each segment when there are no more references to a segment.
Figure 4 illustrates the difference between the characteristic space profiles for a reference-counting garbage collector and for a raark-and-sweep or two-space copying collector.
