用 vttest 測試 terminal 程式實做的相容性

看到「Wez's Terminal」,又一個用 GPU 加速的 terminal 專案,跑去翻一下 Hacker News 上的討論,意外的翻到有趣的東西:「Wezterm – A GPU-accelerated cross-platform terminal emulator and multiplexer (github.com/wez)」。

目前最前面的討論是這個:

I just saw this and after a quick checkout of the latest release (which is what I can quickly install), I feel a bit disappointed. Here is yet another GPU-accelerated terminal that claims to be a VT500 (judging by its Device Attributes report), sets TERM to xterm-256color, while having holes in basic VT100 support (just ran VTTEST in it and saw glaring issues, need not look further than basic VT100 tests, TAB setting/resetting, cursor save/restore).

比較有趣的是裡面提到了 vttest 這套測試軟體可以測 terminal 的標準相容性,在 vttest 的官網上有提到可以測 VT100VT220VT520

Vttest tests the compatibility (demonstrates the non-compatibility) of so-called “VT100-compatible” terminals. In conformance of the good old hacker traditions, the only documentation of this program is the source code itself. To understand it, you also need a copy of the original VT100 manual from DEC.

Additional tests (past version 1.7) are provided for analysis of vt220 through vt520 terminals, as well as variants of xterm.

另外比較驚訝的是,terminal 下可以作到這樣的效果 (這邊看官方的截圖應該是 VT420?):

回到原來講標準相容性的問題,對於泡在 terminal 下的人來說超級重要,有工具可以測試幫助不少... vttest 這套程式在 Ubuntu 內可以直接裝來用:「Ubuntu – Package Search Results -- vttest」。

Dolt,本機開發測試用的 MySQL server

看到「Dolt is Git for Data!」這個專案,是個在本機上跑的 MySQL server,另外可以在上面的資料進行版本控制,看起來很適合本機開發測試。

首先抓下來可以看到沒幾個檔案 (這是 linux-amd64 版),也可以看到跟 Git 的關係:

$ tree
.
├── bin
│   ├── dolt
│   ├── git-dolt
│   └── git-dolt-smudge
└── LICENSES

然後用 bin/dolt sql-server -P 3307 -u root -p passw0rd 跑就可以把一個相容於 MySQL 的伺服器跑在 port 3307,然後用 mysql -h 127.0.0.1 --port 3307 -u root -p 就可以輸入密碼 passw0rd 登入進去:

$ mysql -h 127.0.0.1 --port 3307 -u root -p
Enter password:
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 1
Server version: 5.7.9-Vitess

可以從 Server version 看到專案是用了 Vitess 實做的 MySQL 界面。

另外測了一下,透過連線所做的變更 (像是 CREATE DATABASECREATE TABLE,以及 CRUD 中的 CUD) 是不會寫回磁碟裡的,嘗試了不同的設定,不管改什麼都是這樣,應該是故意設計成這樣。

在本機跑 test case 測試應該還不錯,會比 SQLite:memory: 更接近 MySQL 一些,不過在 CI 裡的話應該是可以直接把 MySQL 跑起來...

Travis CI 停止提供服務給 Open Source 專案

Hacker News Daily 上看到這個,在講 Travis CI 終止對 open source 專案的服務:「Travis CI is no longer providing CI minutes for open source projects」。

有不少專案已經改用其他 CI 服務的 free tier 做,像是 GitHub ActionsCircleCI 都有提供。

看了一下 Hacker News 上的討論,不少人是可以理解不會有永遠免費的午餐,只是這次 Travis CI 的處理讓大家覺得比較討厭的是,一方面官方一直跟 open source community 說我們很願意支援 open source community (前幾個禮拜官方 blog 還有發文重申這件事情),另外一方面是一直在朝著關閉服務走:從限制 10K credits 開始,到現在不會再提供 credit 給 open source 專案。

有人整理了對應的時間軸:

? 2018: Travis CI announces they are starting the process of merging travis-ci.org, which provided free builds for OSS projects, into travis-ci.com, which until then was only for paying customers. They promise OSS builds will continue to be free.

? 2020: Travis CI announces they are shutting down travis-ci.org at the end of the year and all projects have to move to travis-ci.com. They promise OSS builds will continue to be free.

Early November 2020: travis-ci.com switches from providing unlimited builds for OSS to only providing 10k one-time credits by default. Projects that meet certain guidelines (e.g. no one paid to work on them) can apply for recurring credits.

Later in November 2020: CI for many OSS projects that had migrated to travis-ci.com starts to fail, as they've exhausted their 10K credits.

Dec 2020: If what is reported here is accurate, Travis CI stop providing any recurring OSS credits. CI breaks for the remaining OSS projects on travis-ci.com.

Jan 2021: travis-ci.org shuts down. CI will be broken for all projects using it. They'll have the option of migrating to travis-ci.com, but will soon break again as they exhaust their 10k credits.

這種服務非常吃 CPU resource,大型專案如果每個 push 或是每個 pull request 都跑一輪完整的測試,成本應該不低,大概可以理解為什麼 Travis CI 會這樣決定,不過態度就...

其他家有提供 free tier 的 CI 最近應該會湧入不少人,這幾個月可以看看其他家會不會也跟進,另外一方面應該也會有人開始自架?

Load Impact 的 k6 網站壓測軟體

這幾天在 Hacker News 上看到 Load Impact 推出的 k6 壓測程式,結合了 Golang 的執行效率與 JavaScript 的操作語法,讓使用者可以很簡單的進行壓力測試,在 Hacker News 上也有蠻正向的反應:「K6: Like unit testing, for performance (github.com/loadimpact)」,我唯一會在意的應該是 AGPLv3 的部份...

先看了一下資訊,看起來「Load Impact」是公司名稱,「LoadImpact」則是產品名稱,然後現在要改名變成「k6」與「k6 Cloud」:

Load Impact is now k6

Due to the success and rapid growth of the k6 open source load testing tool we decided to rebrand the LoadImpact product as k6 Cloud!

k6 裡面設計了 VU (Virtual User) 的概念,如同字面上的意義,VU 是虛擬的使用者,就技術上來說,每個 VU 都是在獨立的 JavaScript runtime 裡跑:

Each virtual user (VU) executes your script in a completely separate JavaScript runtime, parallel to all of the other running VUs.

然後他們居然把 JavaScript 裡面最「經典」的 async 架構給拔了,所以就不需要一堆 callback & promise 架構,用起來就爽很多:

For simplicity, unlike many other JavaScript runtimes, a lot of the operations in k6 are synchronous. That means that, for example, the let response = http.get("https://test-api.k6.io/") call from the Running k6 example script will block the VU execution until the HTTP request is completed, save the response information in the response variable and only then continue executing the rest of the script - no callbacks and promises needed.

翻了一下 Hacker News 上的討論與程式碼,看起來 JavaScript runtime 這部份是用 Golang 寫的 goja

文件裡面給了不少範例,像是在「Running k6」這邊有直接給出怎麼壓測,10 個 VU 跑 30 秒:

k6 run --vus 10 --duration 30s script.js

另外在 repository 裡面,「samples」這個目錄下有不少範例,可以直接先看過一次從裡面學到不少功能,之後再回去翻一次 manual,應該就會更熟悉...

隨便測了一下還蠻容易上手的,加上有 apt repository 可以直接納入系統管理,看起來應該會放著跑,之後找機會用看看,也許打 API 之類的...

加州法院認為 Uber 與 Lyft 的司機是員工

先前在其他地區已經有很多判例了,這次會特別記錄下來是因為加州是 UberLyft 的總部:「Uber and Lyft ordered by California judge to classify drivers as employees」。

裡面有提到了去年九月加州政府通過了法案 (California Assembly Bill 5,簡稱 AB 5),把 ABC Test 放進法律,取代了之前的 Borello test,用來判斷聘顧關係 (是否為員工,或是獨立的合約關係):

Under the ABC test, a worker is considered an employee and not an independent contractor, unless the hiring entity satisfies all three of the following conditions:

  • The worker is free from the control and direction of the hiring entity in connection with the performance of the work, both under the contract for the performance of the work and in fact;
  • The worker performs work that is outside the usual course of the hiring entity’s business; and
  • The worker is customarily engaged in an independently established trade, occupation, or business of the same nature as that involved in the work performed.

現在需要這三點都成立才會認定為獨立的合約聘顧關係,雖然還有上訴的機會,但翻盤的機率應該不高,記得這個法案當初就是針對 Uber 跟 Lyft...

Cloudflare 也推出自己的 Speed Test 服務

Cloudflare 推出了自己的 Speed Test 服務:「Test your home network performance」。

這個服務跟 Netflix 推出的 fast.com 類似,測試的是使用者端到 Netflix (或是 Cloudflare) 中間的速度,主要的目的還是公關 (PR),所以看看就好,實際上用 Speedtest 測出來會比較有參考價值,而且可以選擇不同的點測試...

不過這讓我想到之前有人測出來遠傳會對偵測使用者要使用 Speedtest 測試時開放速限的情況 (像是「遠傳吃到飽只有 Speedtest 沒限速」這篇),然後就有各種定時去打 Speedtest 觸發開放速限的方法...

目前好像只剩下這篇活著,內文提到的是 Android 上的方法,另外推文有人提到 iOS 下的方法:「[心得] 在Android破解遠X限速」,如果有遇到的可以用看看...

phk 的 ministat

Facebook 上看到朋友貼的統計分析小工具:「A small tool to do the statistics legwork on benchmarks etc.」,看了一下原來是 phk 寫的,後來被拉出來獨立跑...

從兩個檔案讀取兩組數列,然後用 Student's t-test 分析的小工具,在 manpage 裡面可以看到說明:

Specify desired confidence level for Student's T analysis. Possible values are 80, 90, 95, 98, 99 and 99.5 %

雖然說有些人不喜歡 Student's t-test 被濫用,不過畢竟還是一套合理的數學方法,在分析的時候可以快速的判斷...

翻了一下發現 Ubuntu 也有得裝:「Ubuntu – Package Search Results -- ministat」。

詩篇的作者抱怨不知道自己詩篇考題的答案...

2017 年的文章,最近不知道為什麼冒出來,但還蠻有趣的...

看到「I Can’t Answer These Texas Standardized Test Questions About My Own Poems」這篇,Sara Holbrook 收到信件跑來問問題 (節錄前面的部份):

Hello Mrs. Holbrook. My name is Sean, and I’m an 8th grade English teacher in Texas. I’m attempting to decipher the number of stanzas in your poem, ‘Midnight’. This isn’t clear from the formatting in our most recent benchmark. The assessment asks the following question:

作者最後的抱怨也很有趣:

My final reflection is this: any test that questions the motivations of the author without asking the author is a big baloney sandwich. Mostly test makers do this to dead people who can’t protest. But I’m not dead.

I protest.

這邊其實也是在偷戳「作者之死」現象... 另外一則也有類似的情況,發生的早一點的台灣 (2016) XDDD

文學的過度解讀現象 XDDD

Amazon DynamoDB 提供 Docker Image 讓開發者可以在本地端測試

AWS 推出了 Amazon DynamoDB 的相容 Docker Image,讓開發者可以在本地端測試 DynamoDB 的 API:「Use Amazon DynamoDB Local More Easily with the New Docker Image」,在 amazon/dynamodb-local 這邊可以拉到,裡面其實是包 Java:

DynamoDB local is now available to download as a self-contained Docker image or a .jar file that can run on Microsoft Windows, Linux, macOS, and other platforms that support Java.

這樣在 Continuous Integration (CI) 的過程裡面也可以拉起 service 測試...

MySQL 裡 performance_schema 對效能的影響

最近在弄 MySQLperforemance_schema,開起來後發現效能影響沒有很大,跟印象中不太一樣... 找了一下文章發現 Percona 在 2017 年年初時有針對效能測試過:「Performance Schema Benchmarks: OLTP RW」。重點在這張圖:

圖上可以看到 Default 其實對效能的影響有限,另外文章也整理出來,有哪些設定對效能影響不會太大,可以考慮平常就開著:

Using Performance Schema with the default options, Memory, Metadata Locks and Statements instrumentation doesn’t have a great impact on read-write workload performance. You might notice slowdowns with Stages instrumentation after reaching 32 actively running parallel connections. The real performance killer is Waits instrumentation. And even with it on, you will start to notice a performance drop only after 10,000 transactions per second.