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

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

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

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

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

Allow me to say that I would long since have committed suicide had desisting made me a professor of Latin.

Love has been described as a three-ring circus: First comes the engagement ring, then the wedding ring, and after that the suffering.

There's a tremendous difference between alone and lonely. You could be lonely in a group of people. I like being alone. I like eating by myself. I go home at night and just watch a movie or hang out with my dog. I have to exert myself and really say, oh God, I've got to see my friends 'cause I'm too content being by myself.

If I fall, I fall. I'll rise up like anybody else.

Let us be grateful to the people who make us happy; they are the charming gardeners who make our souls blossom.

I get bored of music really easily, so I always try and make music that makes sense, but then it's just a little bit wrong.

It's nice that there are movies and songs about romance - it's what motivates us as human beings. I'm all for being brainwashed by rom-coms.

I've seen lights in the sky, I've seen UFOs, I've even seen something on the ground that I can't explain, but I've never actually seen a being. I wish I had.

For you who no longer posses it, freedom is everything, for us who do, it is merely an illusion.

Tower Records was a place to meet your friends, your co-workers or a place to meet new friends who shared a common love of music, literature and all things cultural.

A military presence does not need to be used to be useful.

That's what's so great about television. You're able to tell this long story, where you couldn't really do that in a film because you have to tell a story in an hour and a half or two hours.

The art world can be very intimidating because it's just so vast. You talk to people who are really clued in to all the young artists and coming into it you're never going to be able to catch up immediately, even though there's pressure to.

If we can put a man on the moon and sequence the human genome, we should be able to devise something close to a universal digital public library.

Oliver Stone might think he's a guy who chews with his mouth open and yells at the hired help, but the George W. Bush I've spent nearly three hours with is a warm, funny, smart, engaged, compassionate, patriotic, decent and honorable man.

As a teenager at high school, I felt like an outsider.

When I saw 'Legally Blonde' on Broadway, I rang my agent and said 'I want to be seen for this,' but the rest weren't big choices, really. 'Hedda Gabler' was a phone call offering it to me, and as I've said before quite embarrassingly, I didn't know the play, so I didn't sit there thinking 'I would now like to tackle Ibsen.'

Life and death have been lacking in my life.

Peace can be promoted by the limitation of arms and by the creation of the instrumentality for peaceful settlement of controversies. But it will become a reality only through self-restraint and active effort in friendliness and helpfulness.

Why harass with eternal purposes a mind to weak to grasp them?

Your next SMS will probably be around longer, and remain more legible, than your tombstone. For, unlike your tombstone or even your mortal coil, your texts may be worth something.

Create form out of the nature of the task with the means of our time. This is our work.

My best hostess tip is to have good food and really good music!

The thing that people seem to miss about not just Google, but also our competitors, Yahoo, eBay and so forth, is that there's an awful lot of communities that have never been served by traditional media.