presto-main/src/main/java/io/prestosql/operator/OperatorContext.java/OperatorContext/updatePeakMemoryReservations
class OperatorContext:    private void updatePeakMemoryReservations()
    {
        long userMemory = operatorMemoryContext.getUserMemory();
        long systemMemory = operatorMemoryContext.getSystemMemory();
        long revocableMemory = operatorMemoryContext.getRevocableMemory();
        long totalMemory = userMemory + systemMemory;
        peakUserMemoryReservation.accumulateAndGet(userMemory, Math::max);
        peakSystemMemoryReservation.accumulateAndGet(systemMemory, Math::max);
        peakRevocableMemoryReservation.accumulateAndGet(revocableMemory, Math::max);
        peakTotalMemoryReservation.accumulateAndGet(totalMemory, Math::max);
    }