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diff --git a/zola-static/content/blog/emacs-garbage-collection.md b/zola-static/content/blog/emacs-garbage-collection.md new file mode 100644 index 0000000..1784be9 --- /dev/null +++ b/zola-static/content/blog/emacs-garbage-collection.md @@ -0,0 +1,40 @@ ++++ +title = "Solving Emacs Garbage Collection Stutters" +date = 2025-05-12 ++++ + +The more you load Emacs up with packages, the more it starts to show its age. Throw on a theme and an lsp client, and you might start to notice frequent stuttering. + +This problem was very frustrating for me - I dealt with it for months, and considered quitting Emacs altogether. I want to be able to hold `C-n` and linearly move down the document, micro-stutter *free*. + + +# Garbage Collection +It turns out that the problem wasn't that packages were executing slowly, it was the garbage that they were building up. Emacs' garbage collector waits until a byte threshold has been reached before executing. +> This value feels relatively low for a modern computer - only `800KB`. + +Once threshold is reached the garbage collection process takes time, and causes the stutter. If you want to see just how often this triggers the GC, try setting `garbage-collection-messages` to non nil (you might be surprised how often it triggers). As with most things in Emacs, you can tune this behaviour. + +Opinions differ. +- Some people recommend **increasing** the threshold, leading to longer times without triggering the GC but longer stutters. +- Others recommend **lowering** the threshold, causing more frequent GC triggers but smaller stutters. +- The minibuffer (especially with packages like `vertico`) can use a lot of memory, so some [recommend](https://bling.github.io/blog/2016/01/18/why-are-you-changing-gc-cons-threshold/) increasing the threshold only when using it. + +# The Solution +In my opinion, the best solution is to garbage collect **when idle**. When editing, you're often pausing briefly - and if there is little garbage, Emacs can collect it very quickly. +I also *basically* disable the threshold entirely when in the minibuffer. Here's the code from my `init.el`. + +```lisp +(defun my-minibuffer-setup-hook () + (setq gc-cons-threshold most-positive-fixnum)) + +(defun my-minibuffer-exit-hook () + (setq gc-cons-threshold 800000000)) + +(setq gc-cons-threshold most-positive-fixnum) + +(run-with-idle-timer 1.2 t 'garbage-collect) +``` + +I have been using this for a few months and it's worked perfectly. Even when I try my best to notice the garbage collection, I can't. + +> There is a package which does the same thing, called [the Garbage Collector Magic Hack](https://github.com/emacsmirror/gcmh). Personally I prefer a lower idle time, and keeping it in my own config. |