4.10.4 Monitoring Garbage Collections

By default, the user is given no indication that the garbage collector is operating. If no program ever runs out of space and no program using a lot of global stack space requires an inordinate amount of processing time, then such information is unlikely to be needed.

However, if a program thought to be using much global stack space runs out of space or runs inordinately slowly, then the user may want to determine whether more or less frequent garbage collections are necessary. Information obtained from the garbage collector by turning on the gc_trace Prolog flag can be helpful in this determination.