As currently implemented, this is only considering the amount of memory that is so-called "mutator free". The definition of good progress, however, considers all available memory, including memory that has reserved for the young-gen collector and for the old-gen collector.

The problem with the configuration as currently implemented is that this forces upgrade to full gc even when full gc is not required.

Triggering Full GC is highly undesirable as it repeats all the work that was just completed by concurrent threads combined with degenerated STW threads.