An assert in MetaspaceGC::compute_new_size is always true:

size_t max_shrink_bytes = capacity_until_GC - minimum_desired_capacity;
assert(max_shrink_bytes >= 0, err_msg("max_shrink_bytes " SIZE_FORMAT,
  max_shrink_bytes));

since size_t always is larger than or equal to zero.

The assert should be rewritten to instead compare minimum_desired_capacity and capacity_until_GC.