presto-main/src/main/java/io/prestosql/execution/MemoryRevokingScheduler.java/MemoryRevokingScheduler/memoryRevokingNeeded
class MemoryRevokingScheduler:    private boolean memoryRevokingNeeded(MemoryPool memoryPool)
    {
        return memoryPool.getReservedRevocableBytes() > 0
                && memoryPool.getFreeBytes() <= memoryPool.getMaxBytes() * (1.0 - memoryRevokingThreshold);
    }