alt Hacker NewsNote that this is an active discussion where we're trying to get to a point of clarity where we can promote to an issue (when it is actionable). The discussion is open and this is the system working as intended!
I want to clarify though that there isn't a known widespread "memory leak issue." You didn't say "widespread", but just in case that is taken by anyone else. :) To clarify, there are a few challenges here:
1. The report at hand seems to affect a very limited number of users (given the lack of reports and information about them). There are lots of X meme posts about Ghostty in the macOS "Force Close" window using a massive amount of RAM but that isn't directly useful because that window also reports all the RAM _child processes_ are using (e.g. if you run a command in your shell that consumes 100 GB of RAM, macOS reports it as Ghostty using 100 GB of RAM). And the window by itself also doesn't tell us what you were doing in Ghostty. It farms good engagement, though.
2. We've run Ghostty on Linux under Valgrind in a variety of configurations (the full GUI), we run all of Ghostty's unit tests under Valgrind in CI for every commit, and we've run Ghostty on macOS with the Xcode Instruments leak checker in a variety of configurations and we haven't yet been able to find any leaks. Both of these run fully clean. So, the "easy" tools can't find it.
3. Following point 1 and 2, no maintainer familiar with the codebase has ever seen leaky behavior. Some of us run a build of Ghostty, working full time in a terminal, for weeks, and memory is stable.
4. Our Discord has ~30K users, and within it, we only have one active user who periodically gets a large memory issue. They haven't been able to narrow this down to any specific reproduction and they aren't familiar enough with the codebase to debug it themselves, unfortunately. They're trying!
To be clear, I 100% believe that there is some kind of leak affecting some specific configuration of users. That's why the discussion is open and we're soliciting input. I even spent about an hour today on the latest feedback (posted earlier today) trying to use that information to narrow it down. No dice, yet.
If anyone has more info, we'd love to find this. :)
Replies
I have a one bit that might be useful that I learned from debugging/optimizing Emacs.
macOS' Instruments tool only checks for leaks when it can track allocations and it is limited to ~256 stack depth. For recursive calls or very deep stacks (Emacs) some allocations aren't tracked and only after setting malloc history flags [0] I started seeing some results (and leaks).
Another place I'm investigating (for Emacs) is that AppKit lifecycle doesn't actually align with Emacs lifecycle and so leaks are happening on the AppKit and that has ZERO to do with application. Seems that problem manifests mostly on a high end specs (multiple HiDPI displays with high variable refresh rate, powerful chip etc.)
Probably nothing you haven't investigated yet, but it is similar to the ghost (pun intended) I've been looking for.
[0]: https://developer.apple.com/library/archive/documentation/Pe...
I’ve been a very happy user for 2025, with some edge cases around the terminal not working on remote shells. I haven’t seen any memory leaks, but wanted to say I appreciate this detailed response.
Valgrind won’t show you leaks where you (or a GC) still holds a reference. This could mean you’re holding on to large chunks of memory that are still referenced in a closure or something. I don’t know what language or anything about your project, but if you’re using a GC language, make sure you disable GC when running with valgrind (a common mistake). You’ll see a ton of false positives that the GC would normally clean up for you, but some of those won’t be false positives.
This illustrates the difficulty of maintaining a separation between bugs and discussions:
> To be clear, I 100% believe that there is some kind of leak affecting some specific configuration of users
In this case it seems you believe a bug exists, but it isn't sufficiently well-understood and actionable to graduate to the bug tracker.
But the threshold of well-understood and actionable is fuzzy and subjective. Most bugs, in my experience, start with some amount of investigative work, and are actionable in the sense that some concrete steps would further the investigation, but full understanding is not achieved until very late in the game, around the time I am prototyping a fix.
Similarly the line between bug and feature request is often unclear. If the product breaks in specific configuration X, is it a bug, or a request to add support for configuration X?
I find it easier to have a single place for issue discussion at all stages of understanding or actionability, so that we don't have to worry about distinctions like this that feel a bit arbitrary.