Zed hangs on large null file

[onxcy]

Open a file with 10mb of null bytes causes Zed to hang/crash consuming 60+GB of real memory.

Example file:
https://github.com/jamesward/play-load-tests/raw/refs/heads/master/public/10mb.txt

original report

Check for existing issues

• Completed

Describe the bug / provide steps to reproduce it

Use zed to open the file in the link
Zed gets stuck

https://github.com/jamesward/play-load-tests/blob/master/public/10mb.txt

VS Code opens the file without any lag

Zed Version and System Specs

Zed: v0.170.1 (Zed)
OS: macOS 15.2.0
Memory: 16 GiB
Architecture: aarch64

Darwin 24.2.0 Darwin Kernel Version 24.2.0: Fri Dec  6 19:04:03 PST 2024; root:xnu-11215.61.5~2/RELEASE_ARM64_T8132 arm64

If applicable, add screenshots or screencasts of the incorrect state / behavior

No response

If applicable, attach your Zed.log file to this issue.

Zed.log

[notpeter]

I can reproduce. The linked file is just 10MB of null bytes.
Doing it with 1MB makes Zed super slow
Doing it with 10MB makes Zed hang (60GB of ram allocated)

dd if=/dev/zero of=null-file-1mb.txt bs=1M count=1
dd if=/dev/zero of=null-file-10mb.txt bs=10M count=1

Potentially related:

• Large file performance #4701

Hang log

2025-01-23T13:33:53.012861-05:00 [ERROR] Suspected hang on main thread:
zed::reliability::monitor_main_thread_hangs::handle_backtrace_signal::handle_sigusr2::h3b6343c323125168
__os_alloc_slow
editor::element::LineWithInvisibles::from_chunks::h1bd92b6cbbeb8ccf
<editor::element::EditorElement as gpui::element::Element>::prepaint::{{closure}}::{{closure}}::{{closure}}::h733f8e120e6284de
<editor::element::EditorElement as gpui::element::Element>::prepaint::{{closure}}::h2d14b1f98888162a
<editor::element::EditorElement as gpui::element::Element>::prepaint::h2aa75c13925ea226
<gpui::element::Drawable<E> as gpui::element::ElementObject>::prepaint::hb74f9915df675607
gpui::element::AnyElement::prepaint::hfb24811c24228f32
<gpui::view::AnyView as gpui::element::Element>::prepaint::hd0c3691899c67481
<gpui::element::Drawable<E> as gpui::element::ElementObject>::prepaint::h8b49ef322b257535
gpui::element::AnyElement::prepaint::hfb24811c24228f32
gpui::elements::div::Interactivity::prepaint::{{closure}}::{{closure}}::{{closure}}::h6e892ad2baee7d60
gpui::elements::div::Interactivity::prepaint::{{closure}}::{{closure}}::ha07cc8ab16d300b5
gpui::elements::div::Interactivity::prepaint::{{closure}}::h4c3f052a0a12fef0
<gpui::elements::div::Div as gpui::element::Element>::prepaint::h2653c0462afde6fe
<gpui::element::Drawable<E> as gpui::element::ElementObject>::prepaint::h23d11cac4536dd3b
gpui::element::AnyElement::prepaint::hfb24811c24228f32
gpui::elements::div::Interactivity::prepaint::{{closure}}::{{closure}}::{{closure}}::h6e892ad2baee7d60
gpui::elements::div::Interactivity::prepaint::{{closure}}::{{closure}}::ha07cc8ab16d300b5
gpui::elements::div::Interactivity::prepaint::{{closure}}::h4c3f052a0a12fef0
<gpui::elements::div::Div as gpui::element::Element>::prepaint::h2653c0462afde6fe
<gpui::element::Drawable<E> as gpui::element::ElementObject>::prepaint::h23d11cac4536dd3b
gpui::element::AnyElement::prepaint::hfb24811c24228f32
<gpui::view::AnyView as gpui::element::Element>::prepaint::{{closure}}::hb05d21acd27882b5
<gpui::view::AnyView as gpui::element::Element>::prepaint::hd0c3691899c67481
<gpui::element::Drawable<E> as gpui::element::ElementObject>::prepaint::h8b49ef322b257535
gpui::element::AnyElement::prepaint::hfb24811c24228f32
gpui::elements::div::Interactivity::prepaint::{{closure}}::{{closure}}::{{closure}}::h6e892ad2baee7d60
gpui::elements::div::Interactivity::prepaint::{{closure}}::{{closure}}::ha07cc8ab16d300b5
gpui::elements::div::Interactivity::prepaint::{{closure}}::h4c3f052a0a12fef0
<gpui::elements::div::Div as gpui::element::Element>::prepaint::h2653c0462afde6fe
<gpui::element::Drawable<E> as gpui::element::ElementObject>::prepaint::h23d11cac4536dd3b
gpui::element::AnyElement::prepaint::hfb24811c24228f32
<gpui::element::Drawable<E> as gpui::element::ElementObject>::prepaint::h77e520462157ae34
gpui::element::AnyElement::prepaint::hfb24811c24228f32
gpui::elements::div::Interactivity::prepaint::{{closure}}::{{closure}}::{{closure}}::h6e892ad2baee7d60
gpui::elements::div::Interactivity::prepaint::{{closure}}::{{closure}}::ha07cc8ab16d300b5
gpui::elements::div::Interactivity::prepaint::{{closure}}::h4c3f052a0a12fef0
<gpui::elements::div::Div as gpui::element::Element>::prepaint::h2653c0462afde6fe
<gpui::element::Drawable<E> as gpui::element::ElementObject>::prepaint::h23d11cac4536dd3b
gpui::element::AnyElement::prepaint::hfb24811c24228f32
gpui::elements::div::Interactivity::prepaint::{{closure}}::{{closure}}::{{closure}}::h6e892ad2baee7d60
gpui::elements::div::Interactivity::prepaint::{{closure}}::{{closure}}::ha07cc8ab16d300b5
gpui::elements::div::Interactivity::prepaint::{{closure}}::h4c3f052a0a12fef0
<gpui::elements::div::Div as gpui::element::Element>::prepaint::h2653c0462afde6fe
<gpui::element::Drawable<E> as gpui::element::ElementObject>::prepaint::h23d11cac4536dd3b
gpui::element::AnyElement::prepaint::hfb24811c24228f32
gpui::elements::div::Interactivity::prepaint::{{closure}}::{{closure}}::{{closure}}::h6e892ad2baee7d60
gpui::elements::div::Interactivity::prepaint::{{closure}}::{{closure}}::ha07cc8ab16d300b5
gpui::elements::div::Interactivity::prepaint::{{closure}}::h4c3f052a0a12fef0
<gpui::elements::div::Div as gpui::element::Element>::prepaint::h2653c0462afde6fe
<gpui::element::Drawable<E> as gpui::element::ElementObject>::prepaint::h23d11cac4536dd3b
gpui::element::AnyElement::prepaint::hfb24811c24228f32
gpui::elements::div::Interactivity::prepaint::{{closure}}::{{closure}}::{{closure}}::h6e892ad2baee7d60
gpui::elements::div::Interactivity::prepaint::{{closure}}::{{closure}}::ha07cc8ab16d300b5
gpui::elements::div::Interactivity::prepaint::{{closure}}::h4c3f052a0a12fef0
<gpui::elements::div::Div as gpui::element::Element>::prepaint::h2653c0462afde6fe
<gpui::element::Drawable<E> as gpui::element::ElementObject>::prepaint::h23d11cac4536dd3b
gpui::element::AnyElement::prepaint::hfb24811c24228f32
gpui::elements::div::Interactivity::prepaint::{{closure}}::{{closure}}::{{closure}}::h6e892ad2baee7d60
gpui::elements::div::Interactivity::prepaint::{{closure}}::{{closure}}::ha07cc8ab16d300b5
gpui::elements::div::Interactivity::prepaint::{{closure}}::h4c3f052a0a12fef0
<gpui::elements::div::Div as gpui::element::Element>::prepaint::h2653c0462afde6fe
<gpui::element::Drawable<E> as gpui::element::ElementObject>::prepaint::h23d11cac4536dd3b
gpui::element::AnyElement::prepaint::hfb24811c24228f32
gpui::elements::div::Interactivity::prepaint::{{closure}}::{{closure}}::{{closure}}::h6e892ad2baee7d60
gpui::elements::div::Interactivity::prepaint::{{closure}}::{{closure}}::ha07cc8ab16d300b5
gpui::elements::div::Interactivity::prepaint::{{closure}}::h4c3f052a0a12fef0
<gpui::elements::div::Div as gpui::element::Element>::prepaint::h2653c0462afde6fe
<gpui::element::Drawable<E> as gpui::element::ElementObject>::prepaint::h23d11cac4536dd3b
gpui::element::AnyElement::prepaint::hfb24811c24228f32
gpui::elements::div::Interactivity::prepaint::{{closure}}::{{closure}}::{{closure}}::h6e892ad2baee7d60
gpui::elements::div::Interactivity::prepaint::{{closure}}::{{closure}}::ha07cc8ab16d300b5
gpui::elements::div::Interactivity::prepaint::{{closure}}::h4c3f052a0a12fef0
<gpui::elements::div::Div as gpui::element::Element>::prepaint::h2653c0462afde6fe
<gpui::element::Drawable<E> as gpui::element::ElementObject>::prepaint::h23d11cac4536dd3b
gpui::element::AnyElement::prepaint::hfb24811c24228f32
gpui::elements::div::Interactivity::prepaint::{{closure}}::{{closure}}::{{closure}}::h6e892ad2baee7d60
gpui::elements::div::Interactivity::prepaint::{{closure}}::{{closure}}::ha07cc8ab16d300b5
gpui::elements::div::Interactivity::prepaint::{{closure}}::h4c3f052a0a12fef0
<gpui::elements::div::Div as gpui::element::Element>::prepaint::h2653c0462afde6fe
<gpui::element::Drawable<E> as gpui::element::ElementObject>::prepaint::h23d11cac4536dd3b
gpui::element::AnyElement::prepaint::hfb24811c24228f32
<gpui::view::AnyView as gpui::element::Element>::prepaint::hd0c3691899c67481
<gpui::element::Drawable<E> as gpui::element::ElementObject>::prepaint::hb4bdce46d0c9f64d
gpui::element::AnyElement::prepaint::hfb24811c24228f32
gpui::window::WindowContext::draw::h23dcd3e09c187f8d
gpui::window::Window::new::{{closure}}::{{closure}}::h5214a420031dabfa
gpui::window::Window::new::{{closure}}::hd357fe3d1909fa8f
gpui::platform::mac::window::step::hd3f5b22f168c2109

[osiewicz]

This would be just as reproducible with any file with long lines (note that file with only nulls is still a valid, albeit weird, UTF-8 file); the underlying issue is that we always lay out full line, so we have to go through about ~200k text fragments. I wonder why it's not hitting the line cache though, I'd expect that to take effect the first time we lay out the line?