13的話

這週沒有什麼開發者新聞，所以就拿台灣還買不到的 M1 繼續轟炸各位。

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🍴What went wrong with the libdispatch. A tale of caution for the future of concurrency

本文是 libdispatch efficiency tips 這份經典指南同一位作者最近發表的文章。他提到在 GCD 剛發表的時代，電腦 CPU 在時脈上已經難有突破，開始往多核心發展。Apple 告訴開發者，透過 GCD，thread 可以盡量開。而作者因為這樣而踏入了多執行緒的踩坑經驗。

後來 Apple 也發現他們自己也落入了許多濫用多執行緒的陷阱。包括 iOS 12 效能提升一個原因是把 daemon 的多執行緒改成單執行緒。

David Smith @Catfish_Man

@mxcl @peres What I’m getting at is that we’ve been discovering that the inherent costs of multithreading are a lot higher than they look in microbenchmarks (because microbenches hide cache effects and keep thread pools hot). A lot of iOS 12 perf wins were from daemons going single-threaded.

January 5th 2019

27 Retweets74 Likes

David Smith @Catfish_Man

btw on the subject of “should I use NSOperationQueue or libdispatch”, since it came up, my concrete recommendation is: you should really strongly consider not writing async/concurrent code. I know this sounds weird in 2018, but the cost in complexity *and* performance is high.

January 5th 2019

35 Retweets186 Likes

之後 GCD 也隨著 iPhone 的推出來到 iOS 上。雖然它的語法簡單好用，相對地就不容易防止濫用。因此我覺得複習一下作者的建議（libdispatch efficiency tips）滿好的。

同場加映 libdispatch 的設計者出來講講話

David Zarzycki @davezarzycki

1/n As the designer of libdispatch, I just want to say: I get why people feel this way and I'm sorry that we/I oversold libdispatch to some degree at the time. (And just to be clear, I left Apple many years ago and I still deeply respect them.)

Thomas @tclementdev

Here's my longer take on what went wrong with the libdispatch. A tale of caution for the future of concurrency. https://t.co/EscgiZjM9A

November 27th 2020

66 Retweets326 Likes

下一步呢？Swift 的 concurrent 吧

🔥更多的 M1 心得

首先，Peter Steinberger 的這篇文章很值得一讀，因為他的背景是做 SDK，各種 mobile 相關的情境都會遇到。包括 iOS、Android、Docker、虛擬化、各種開發工具等等。

連續推文，分析為何 M1 跑 Rosetta 也跑得很快（提示：Apple 作弊啊）

Robᵉʳᵗ Graham😷, provocateur @ErrataRob

1/ In case you were wondering: Apple's replacement for Intel processors turns out to work really, really well. Some otherwise skeptical techies are calling it "black magic". It runs Intel code extraordinarily well.

November 25th 2020

858 Retweets2,478 Likes

拿來跑 Minecraft

Marco Arment @marcoarment

Can confirm: I spent a lot of time playing Minecraft (Java ed.) on my M1 MacBook Air over the last few days, and it runs shockingly well in absolute terms — not even grading on a curve to account for Rosetta — in complete silence, with great battery life, only getting a bit warm.

Luke Miani @LukeMiani

Quick Minecraft test... even the MacBook Air running at 10 watts, without a fan, through a translation layer, is running 60fps at native res without getting warm at all. Apple Silicon is nuts lol https://t.co/qpBjCBMv4l

November 22nd 2020

56 Retweets610 Likes

Best Computer

Alex Martin @AlexMartinFR

@marcoarment I've been using an 8 GB Air for a few days and I already want to make it my main machine, that's how freaking good it is 😎 Silence, performances, battery life; everything I value in computing, this beast provide. Behold, the New Best Laptop Ever Made™ has arrived! 🎉

November 22nd 2020

6 Likes

Janne Ojaniemi @Janne_o

@marcoarment I bought the baseline MBA last Friday. I think this is the best and most impressive computer I have used in a long time. I don't miss my 2015 5K iMac with 32GB of RAM at all. This doesn't get hot, no slowdowns, ever. And battery seems to have no end.

November 22nd 2020

7 Likes

快速切螢幕

syumai @__syumai

M1 MacBook Airのディスプレイ切り替えが速すぎると言う噂、本当だった

November 23rd 2020

455 Retweets2,235 Likes

DHH 評論

DHH @dhh

Apple M1.

November 23rd 2020

37 Retweets281 Likes

DHH @dhh

You don't sit around thinking "oh, browsing the web is slow on my decked-out iMac", but then you browse with the M1, and you're like, DAMN, I can actually feel that +50%. 224 on Speedometer 2.0 is just 🤯

November 23rd 2020

10 Retweets151 Likes

回不去了

Marco Arment @marcoarment

Got back to my iMac Pro for the first time in 2 weeks… Why does it build Overcast slower than my new MacBook Air, and what’s this annoying whooshing sound it makes whenever I ask it to do anything useful? (god, I’m ruined)

November 23rd 2020

93 Retweets1,643 Likes

續航力

Jim Dalrymple @jdalrymple

Been using the M1 MBA for the past two hours off and on for normal work stuff. Battery is still at 97%.

November 23rd 2020

2 Retweets62 Likes

Simeon @twolivesleft

M1 Xcode Benchmarks for Codea and Shade

November 26th 2020

39 Retweets287 Likes

效能比較

Robert Payne @robertjpayne

Can confirm our large Swift/C project archives about 1.6x faster on an 13” M1 MBP than a fully decked out 2017 5k iMac. The next chips Apple releases for more powerful machines are gonna be absolutely bonkers.

November 23rd 2020

1 Retweet3 Likes

John Sundell @johnsundell

With M1, I can run Plot's entire test suite (which contains 146 tests) in less than 0,05 seconds! 🤯 At this point, I could almost auto-run all of the tests every time that I change a single character within my code base - now that would be true TDD 😂

November 23rd 2020

32 Retweets526 Likes

Ben Dodson @bendodson

This M1 chip is obscene. Only played with it for a brief time but it's a game changer for iOS developers. Compared to my Mac Pro (3 GHz 8-Core Intel Xeon E5, 32GB RAM) it does incremental builds 5x faster and archives 2x faster with half the RAM, less power, and no heat.

November 24th 2020

1 Retweet9 Likes

Krzysztof Zabłocki @merowing_

my i9-9900k hackintosh with 32 GB ram is at 156 s compile time vs M1 16GB is at 116, I can’t wait for 16’ rMBP / iMac with more powerful processors :)

November 25th 2020

8 Retweets83 Likes

Ben Sandofsky @sandofsky

We can now build Halide and its only dependency, OpenSSL, on M1 Macs. Going from a 2019 16” MacBook Pro (32GB RAM) to an M1 Mac Mini (16GB), the gains are ridiculous. OpenSSL: 10m32s => 5m24s Halide: 0m49s => 0m28s

November 25th 2020

66 Retweets578 Likes

Peter Steinberger @steipete

I took the time to compare clean compile times (debug, our example catalog app for arm64 iOS) MacBook Pro 16-inch 2019 2,4 GHz 8-Core i9 32 GB (fans as loud as it gets): 7:31 min MacBook Air M1 (already warm from doing stuff before, completely silent): 8:49 min Impressive.

November 26th 2020

2 Retweets132 Likes

坑：App Store 下載的 iOS App 會把機器認成 iPad Pro

Marco Arment @marcoarment

iOS devs, FYI: unmodified iOS apps running on M1 Macs appear to report themselves via hw.machine as model identifier “iPad8,6” (iPad Pro 12.9-inch, 3rd-gen, 1TB model). So if you see a very recent spike in your analytics in iPad 12.9 users, that’s probably why.

November 23rd 2020

116 Retweets849 Likes

這下全錯了😂

Yachen Liu @Blankwonder

上周五去朋友公司做客，和他们行政聊天： 她：X 总看到你朋友圈把新的 MacBook Pro 夸上天了，立刻就让我去给他采购了台。 我：他可真够急的。 她：是啊，我找 Apple 的商务立刻就给他下单了，顶配 32G 内存的。 我：……

November 25th 2020

8 Retweets164 Likes

🕸Local Network Privacy FAQ

有在處理區網跟隱私的話，這是 Apple 官方整理的問答。比如「我要怎麼發起 iOS 14 的區網權限要求對話框？」（感謝 @KoromikoNeo 轉推）

⛏Comparing iPhone OS 1.0 with iOS 14 using tree maps

iPhoneOS 考古學。看看從 1.0 到 14 差了多少？

🏃第 12 屆 iT邦幫忙鐵人賽得獎作品

之前我貼過，但這次是得獎名單。跟 iOS 有關的：

• RxSwift / 30天探索之旅—Bing

• 看完眼眶濕濕的App開發者慘烈對抗險惡資安環境血與淚的控訴！—羊小咩

• 30 天從 Swift 學會 Objective-C—ytyubox

💍另類承諾

Casey Neistat @Casey

wife and I don’t wear wedding rings, we show our commitment to one another by exchanging sim trays in our iPhones.

November 24th 2020

20,540 Retweets235,326 Likes

以上就是本期的內容。歡迎轉寄或推薦給同事或開發者朋友。有問題或回饋請直接回覆，或到我的 Twitter 留言。