编程与软件工程journal.stuffwithstuff.com编辑精选
手写你的第一个垃圾回收器
Baby's First Garbage Collector
2013 — 2022，它一次次回到首页
黑点是上首页（≥ 50 分）的那次投稿，空心点是没冲上去的投稿，点越大分数越高。
导读
这是 Bob Nystrom 的经典教程，用不到 100 行 C 代码实现一个标记-清除（mark-and-sweep）垃圾回收器，逐步讲解标记和清除两个阶段的工作原理。文章以玩具级但完整可运行的实现，让读者直观理解 GC 的核心机制。
为什么经久不衰：它把通常藏在教科书和编译器黑盒里的垃圾回收，用极简代码讲得一读就懂，多年反复登上 HN 首页，至今仍是入门 GC 的最佳读物之一。
HN 评论精选
质疑在编译器成熟、GC 性能逼近 C 的今天，手动内存管理还有多少实用价值
我时不时会遇到 Duff 设备或位运算交换变量这类老式 C 优化技巧。它们虽有魅力，但几乎总是被日益成熟的编译器和复杂（或虚拟化）的硬件超越。所以我渐渐觉得，除非面向嵌入式设备，否则玩指针算术甚至手动 malloc/free 越来越没意义。连 Go 这样年轻的语言用相对不成熟的 GC 都能接近 C 的性能，连这种玩具实现都能走得很远——那什么时候不用垃圾回收器还站得住脚呢？我不是在抬杠，我觉得指针算术很精妙，也许我们这代人错过了什么美好的东西，只是这类事情如今已不常实用了。
recuter查看英文原文
So every once in a while I come across old timey C optimizations in the spirit of Duff's device or bit twiddling to swap variables, 'etc 'etc... While they have a certain kind of charm to them they seem to be almost universally bested by increasingly mature compilers and complex (or virtualized) hardware. So I'm kind of coming to the conclusion that clever pointer arithmetic games and even manual malloc/free are increasingly futile unless you're targeting embedded devices. If a young language like Go gets you at least in the same ballpark as C with a relatively immature GC and even toy implementations like the OP take you rather far these days... when is coding without a garbage collector even really defensible anymore? I'm not trolling. I think pointer arithmetic is neat and the aforementioned "optimizations" are magical and possibly my generation has missed out on something wonderful. Seems it just isn't often practical to do that sort of thing anymore. Edit: I'd like to stress that I wasn't talking in absolutes, and asking rather than telling. I'm not sure how to phrase my post better, made some edits nonetheless.
探讨 C 的指针转型等操作与 GC 共存时的根本困难
没深入研究过这个话题，我的第一反应是真指针和垃圾回收器能否共存（而不是人为删掉语言特性）。判断对象是否还在用的条件是有没有引用指向它。但在 C 这样的语言里，你可以把指针转型成别的东西（比如 void 指针存进某种泛型链表），存起来，等 GC 跑完再转回来。这看起来很麻烦。那么完全放弃指针（或至少不做转型、指针算术这类危险操作）是不是拥有 GC 的前提？
phamilton查看英文原文
Not having studied the topic in depth, my first thought is whether true pointers and a garbage collector can coexist (without artificially removing parts of the language). The big condition for knowing if something is still in use is whether any references exist to it. But in a language like C , you could cast a pointer to something else (like a void pointer for some quasi generic linked list), store it somewhere, and then cast it back later after garbage collection has run. That seems like a problematic situation. So is completely giving up on pointers (or just never doing tricky things like casting or pointer arithmetic) a requirement to having a garbage collector?
推荐作者新书中更深入的 GC 章节
作者最近的新书《Crafting Interpreters》中关于垃圾回收的章节，在语言虚拟机的语境下更详细地讲了这些内容，写得非常好——书和这篇 2013 年的博文都是。
benhoyt查看英文原文
The "Garbage Collection" chapter in the OP's recent book Crafting Interpreters goes into this in a bunch more detail (in the context of a language VM): https://craftinginterpreters.com/garbage-collection.html -- so well written, both this and the 2013 blog post.
称赞作者的写作比学术教材更易学易用
像他的《Crafting Interpreters》一样，这篇文章比任何学术教材或课程都更平易近人、易懂、可操作。有时让我惊讶的是，没有这样的材料人们居然还能学到东西。
vsnf查看英文原文
Like his other work, Crafting Interpreters, this is so much more approachable, understandable, and actionable than any academic textbooks or courses on the equivalent subjects are. It sometimes amazes me that one can learn anything at all without material like this.
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