start new:
tmux
start new with session name:
tmux new -s myname
Latency Comparison Numbers (~2012) | |
---------------------------------- | |
L1 cache reference 0.5 ns | |
Branch mispredict 5 ns | |
L2 cache reference 7 ns 14x L1 cache | |
Mutex lock/unlock 25 ns | |
Main memory reference 100 ns 20x L2 cache, 200x L1 cache | |
Compress 1K bytes with Zippy 3,000 ns 3 us | |
Send 1K bytes over 1 Gbps network 10,000 ns 10 us | |
Read 4K randomly from SSD* 150,000 ns 150 us ~1GB/sec SSD |
(by @andrestaltz)
If you prefer to watch video tutorials with live-coding, then check out this series I recorded with the same contents as in this article: Egghead.io - Introduction to Reactive Programming.
I was talking to a coworker recently about general techniques that almost always form the core of any effort to write very fast, down-to-the-metal hot path code on the JVM, and they pointed out that there really isn't a particularly good place to go for this information. It occurred to me that, really, I had more or less picked up all of it by word of mouth and experience, and there just aren't any good reference sources on the topic. So… here's my word of mouth.
This is by no means a comprehensive gist. It's also important to understand that the techniques that I outline in here are not 100% absolute either. Performance on the JVM is an incredibly complicated subject, and while there are rules that almost always hold true, the "almost" remains very salient. Also, for many or even most applications, there will be other techniques that I'm not mentioning which will have a greater impact. JMH, Java Flight Recorder, and a good profiler are your very best friend! Mea
As configured in my dotfiles.
start new:
tmux
start new with session name:
Ruby는 즐거운 언어입니다. Ruby를 사용하다보면 매뉴얼에도 나와있지 않은 '작은 발견'을 만나게 됩니다. 이러한 '발견'은 프로그램의 질이나
Recursion is beautiful. As an example, let's consider this perfectly acceptable example of defining the functions even
and odd
in Scala, whose semantics you can guess:
def even(i: Int): Boolean = i match {
case 0 => true
case _ => odd(i - 1)
}
def odd(i: Int): Boolean = i match {
API | Status Codes |
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[Twitter][tw] | 200, 304, 400, 401, 403, 404, 406, 410, 420, 422, 429, 500, 502, 503, 504 |
[Stripe][stripe] | 200, 400, 401, 402, 404, 429, 500, 502, 503, 504 |
[Github][gh] | 200, 400, 422, 301, 302, 304, 307, 401, 403 |
[Pagerduty][pd] | 200, 201, 204, 400, 401, 403, 404, 408, 500 |
[NewRelic Plugins][nr] | 200, 400, 403, 404, 405, 413, 500, 502, 503, 503 |
[Etsy][etsy] | 200, 201, 400, 403, 404, 500, 503 |
[Dropbox][db] | 200, 400, 401, 403, 404, 405, 429, 503, 507 |