presto-main/src/main/java/io/prestosql/memory/MemoryManagerConfig.java/MemoryManagerConfig/getMaxQueryTotalMemory
class MemoryManagerConfig:    @NotNull
    public DataSize getMaxQueryTotalMemory()
    {
        if (maxQueryTotalMemory == null) {
            return succinctBytes(maxQueryMemory.toBytes() * 2);
        }
        return maxQueryTotalMemory;
    }