static long[] getMemoryUsage(VespaService service) {
        return getMemoryUsage(service, getPageSize());
    }
Return memory usage in bytes for a given process, both resident and virtual is
returned.

@param service The instance to get memory usage for
@return array[0] = memoryResident, array[1] = memoryVirtual (both in bytes)
metrics-proxy/src/main/java/ai/vespa/metricsproxy/service/SystemPoller.java