分层架构需要考虑的另一个因素，是层次之间一定是相邻层互相依赖，数据的流转也只能在相邻的两层之间流转

缓存技术蕴含的是空间换时间的思想；压缩体现的是时间换空间的思想；分布式思想也最初体现在 CPU 的设计和实现上

普通磁盘的寻道时间是 10ms 左右，而相比于磁盘寻道花费的时间，CPU 执行指令和内存寻址的时间都在是 ns（纳秒）级别，从千兆网卡上读取数据的时间是在μs（微秒）级别

某些层次负责的是对下层不同实现的抽象，从而对上层屏蔽实现细节。比方说 VFS 对上层（系统调用层）来说提供了统一的调用接口，同时对下层中不同的文件系统规约了实现模型，当新增一种文件系统实现的时候，只需要按照这种模型来设计，就可以无缝插入到 Linux 文件系统中

分层架构可以让我们更容易做横向扩展。如果系统没有分层，当流量增加时我们需要针对整体系统来做扩展。但是，如果我们按照上面提到的三层架构将系统分层后，那么我们就可以针对具体的问题来做细致的扩展

Happens-Before 并不是说前面一个操作发生在后续操作的前面，它真正要表达的是：前面一个操作的结果对后续操作是可见的

导致可见性的原因是缓存，导致有序性的原因是编译优化，那解决可见性、有序性最直接的办法就是禁用缓存和编译优化

Java 内存模型在 1.5 版本对 volatile 语义进行了增强。怎么增强的呢？答案是一项 Happens-Before 规则

Java 内存模型规范了 JVM 如何提供按需禁用缓存和编译优化的方法

final 修饰变量时，初衷是告诉编译器：这个变量生而不变，可以可劲儿优化

“同一时刻只有一个线程执行”这个条件非常重要，我们称之为互斥。如果我们能够保证对共享变量的修改是互斥的，那么，无论是单核 CPU 还是多核 CPU，就都能保证原子性了。

一个或者多个操作在 CPU 执行的过程中不被中断的特性，称为“原子性”

使用 watch 选项允许我们执行异步操作 (访问一个 API)，限制我们执行该操作的频率，并在我们得到最终结果前，设置中间状态。这些都是计算属性无法做到的

如果 <navigation-link> 没有包含一个 <slot> 元素，则该组件起始标签和结束标签之间的任何内容都会被抛弃。

计算属性是基于它们的响应式依赖进行缓存的。只在相关响应式依赖发生改变时它们才会重新求值。这就意味着只要 message 还没有发生改变，多次访问 reversedMessage 计算属性会立即返回之前的计算结果，而不必再次执行函数

组件是可复用的 Vue 实例，所以它们与 new Vue 接收相同的选项，例如 data、computed、watch、methods 以及生命周期钩子等。仅有的例外是像 el 这样根实例特有的选项

I would vote for Bush if for no other reason than to be at the airport waving off all the people who say they are going to London if he wins again. Someone has got to stay behind.

When I raced with Mercedes, I thought I'd learn German. But my wife didn't want to live in Germany.

I was utterly without worldly ambition because I knew that all that was needed for a rich, full life was a few shillings a week with which to buy SF magazines and beer.

I'm a four-down guy. I can rush the passer and stop the run. I know I can be a difference-maker.

Ignore the people who is always talking behind your back, that's where they belong, behind you.

We recognize that the majority of people who are food-insecure or hungry in the world live in rural areas. And most of them are small holder subsistence farmers.

Why is playing football in Europe considered the pinnacle of our game, yet in other spheres of life, that same phrase - 'being in Europe' - is dismissed with suspicion?

I don't believe in guilt; I believe in living on impulse as long as you never intentionally hurt another person. And don't judge people in your life. I think you should live completely free.

As a songwriter, there's nothing better than winning Song Of The Year. But I couldn't really celebrate, because it wasn't right. Luther wasn't standing next to me, to receive the award.

Forget, forgive; conclude, and be agreed.

I love the water; I love to swim.

Teenagers especially are very, very conscious about what is hip and what is lame and what is square and what is out and what is in, you know. And, I mean, I grew up right there in the middle of a black culture. And I knew dead-on what it was.

But Angela had at least 30% more viewers on the same night at the same time. I mean, she wiped everybody out. But the sponsors don't care when she had the most people. They only care about if there was only a handful of young viewers on the other one.

'm just going to be a good friend to my kid. One thing I definitely want to change is that whole 'I don't want you to make the same mistakes' mentality. My dad didn't have much money growing up; he didn't have much of an education. He forced that on me, and I didn't want it.

Great love isn't two people finding the perfect match in one another. Great love is two people making the choice to be a match.

My father could be very witty, even if the humor was always on the darker side of irony.

I always believed that women have rights and that there are some women that are intelligent enough to claim those rights. There are some others that are stupid enough not to.

I write and write and write, and then I edit it down to the parts that I think are amusing, or that help the storyline, or I'll write a notebook full of ideas of anecdotes or story points, and then I'll try and arrange them in a way that they would tell a semi-cohesive story.

The thing about acting is you don't want to let on how enjoyable it is or then everybody would want to become an actress. But it really is. It's a pleasure to go and exchange your identity.

The volume of your voice does not increase the validity of your argument.

Holding on is believing that theres only a past letting go is knowing that theres a future.

Success is tricky to deal with, both professionally and in your personal life.

I end up pleading my case to alternative programmers - you're telling me that my music is too dark for pop, too pop for alternative, and urban radio won't touch it - so we have a record that doesn't fit in. And what is more alternative than that?

'Jitterbug Perfume' is one of my favorite books.