Thorsten BallandAntonio
0533923f91
This should help with some of the memory problems reported in https://github.com/zed-industries/zed/issues/8436, especially the ones related to large files (see: https://github.com/zed-industries/zed/issues/8436#issuecomment2037442695), by **reducing the memory required to represent a buffer in Zed by ~50%.** ### How? Zed's memory consumption is dominated by the in-memory representation of buffer contents. On the lowest level, the buffer is represented as a [Rope](https://en.wikipedia.org/wiki/Rope_(data_structure)) and that's where the most memory is used. The layers above — buffer, syntax map, fold map, display map, ... — basically use "no memory" compared to the Rope. Zed's `Rope` data structure is itself implemented as [a `SumTree` of `Chunks`](https://github.com/zed-industries/zed/blob/8205c52d2bc204b8234f9306562d9000b1691857/crates/rope/src/rope.rs#L35-L38). An important constant at play here is `CHUNK_BASE`: `CHUNK_BASE` is the maximum length of a single text `Chunk` in the `SumTree` underlying the `Rope`. In other words: It determines into how many pieces a given buffer is split up. By changing `CHUNK_BASE` we can adjust the level of granularity withwhich we index a given piece of text. Theoretical maximum is the length of the text, theoretical minimum is 1. Sweet spot is somewhere inbetween, where memory use and performance of write & read access are optimal. We started with `16` as the `CHUNK_BASE`, but that wasn't the result of extensive benchmarks, more the first reasonable number that came to mind. ### What This changes `CHUNK_BASE` from `16` to `64`. That reduces the memory usage, trading it in for slight reduction in performance in certain benchmarks. ### Benchmarks I added a benchmark suite for `Rope` to determine whether we'd regress in performance as `CHUNK_BASE` goes up. I went from `16` to `32` and then to `64`. While `32` increased performance and reduced memory usage, `64` had one slight drop in performance, increases in other benchmarks and substantial memory savings. | `CHUNK_BASE` from `16` to `32` | `CHUNK_BASE` from `16` to `64` | |-------------------|--------------------| |  |  | ### Real World Results We tested this by loading a 138 MB `*.tex` file (parsed as plain text) into Zed and measuring in `Instruments.app` the allocation. #### standard allocator Before, with `CHUNK_BASE: 16`, the memory usage was ~827MB after loading the buffer. | `CHUNK_BASE: 16` | |---------------------| |  | After, with `CHUNK_BASE: 64`, the memory usage was ~396MB after loading the buffer. | `CHUNK_BASE: 64` | |---------------------| |  | #### `mimalloc` `MiMalloc` by default and that seems to be pretty aggressive when it comes to growing memory. Whereas the std allocator would go up to ~800mb, MiMalloc would jump straight to 1024MB. I also can't get `MiMalloc` to work properly with `Instruments.app` (it always shows 15MB of memory usage) so I had to use these `Activity Monitor` screenshots: | `CHUNK_BASE: 16` | |---------------------| |  | | `CHUNK_BASE: 64` | |---------------------| |  | ### Release Notes Release Notes: - Reduced memory usage for files by up to 50%. --------- Co-authored-by: Antonio <antonio@zed.dev>
Zed
Welcome to Zed, a high-performance, multiplayer code editor from the creators of Atom and Tree-sitter.
Installation
You can download Zed today for macOS (v10.15+).
Support for additional platforms is on our roadmap:
- Linux (tracking issue)
- Windows (tracking issue)
- Web (tracking issue)
For macOS users, you can also install Zed using Homebrew:
brew install zed
Alternatively, to install the Preview release:
brew tap homebrew/cask-versions
brew install zed-preview
Developing Zed
- Building Zed for macOS
- Building Zed for Linux
- Building Zed for Windows
- Running Collaboration Locally
Contributing
See CONTRIBUTING.md for ways you can contribute to Zed.
Licensing
License information for third party dependencies must be correctly provided for CI to pass.
We use cargo-about to automatically comply with open source licenses. If CI is failing, check the following:
- Is it showing a
no license specifiederror for a crate you've created? If so, addpublish = falseunder[package]in your crate's Cargo.toml. - Is the error
failed to satisfy license requirementsfor a dependency? If so, first determine what license the project has and whether this system is sufficient to comply with this license's requirements. If you're unsure, ask a lawyer. Once you've verified that this system is acceptable add the license's SPDX identifier to theacceptedarray inscript/licenses/zed-licenses.toml. - Is
cargo-aboutunable to find the license for a dependency? If so, add a clarification field at the end ofscript/licenses/zed-licenses.toml, as specified in the cargo-about book.