Reduce amount of foreground tasks spawned on multibuffer/editor updates (#41479)

Lukas Wirth created

When doing a project wide search in zed on windows for `hang`, zed
starts to freeze for a couple seconds ultimately starting to error with
`Not enough quota is available to process this command.` when
dispatching windows messages. The cause for this is that we simply
overload the windows message pump due to the sheer amount of foreground
tasks we spawn when we populate the project search.

This PR is an attempt at reducing this.

Release Notes:

- Reduced hangs and stutters in large project file searches

Change summary

crates/editor/src/display_map/wrap_map.rs |  7 +--
crates/editor/src/git/blame.rs            |  1 
crates/go_to_line/src/cursor_position.rs  | 32 +++++++++--------
crates/gpui/src/app/async_context.rs      |  2 
crates/gpui/src/executor.rs               |  1 
crates/language/src/buffer.rs             | 25 +++++++-----
crates/multi_buffer/src/path_key.rs       | 16 ++++---
crates/project/src/buffer_store.rs        | 46 +++++++++++-------------
crates/project/src/git_store.rs           |  1 
crates/project/src/project_tests.rs       |  4 +
crates/search/src/project_search.rs       | 30 +++++++++------
crates/worktree/src/worktree.rs           |  4 +
crates/zed/src/zed.rs                     | 18 +++++---
13 files changed, 101 insertions(+), 86 deletions(-)

Detailed changes

crates/editor/src/display_map/wrap_map.rs 🔗

@@ -568,18 +568,15 @@ impl WrapSnapshot {
             let mut old_start = old_cursor.start().output.lines;
             old_start += tab_edit.old.start.0 - old_cursor.start().input.lines;
 
-            // todo(lw): Should these be seek_forward?
-            old_cursor.seek(&tab_edit.old.end, Bias::Right);
+            old_cursor.seek_forward(&tab_edit.old.end, Bias::Right);
             let mut old_end = old_cursor.start().output.lines;
             old_end += tab_edit.old.end.0 - old_cursor.start().input.lines;
 
-            // todo(lw): Should these be seek_forward?
             new_cursor.seek(&tab_edit.new.start, Bias::Right);
             let mut new_start = new_cursor.start().output.lines;
             new_start += tab_edit.new.start.0 - new_cursor.start().input.lines;
 
-            // todo(lw): Should these be seek_forward?
-            new_cursor.seek(&tab_edit.new.end, Bias::Right);
+            new_cursor.seek_forward(&tab_edit.new.end, Bias::Right);
             let mut new_end = new_cursor.start().output.lines;
             new_end += tab_edit.new.end.0 - new_cursor.start().input.lines;
 

crates/editor/src/git/blame.rs 🔗

@@ -602,6 +602,7 @@ impl GitBlame {
     }
 
     fn regenerate_on_edit(&mut self, cx: &mut Context<Self>) {
+        // todo(lw): hot foreground spawn
         self.regenerate_on_edit_task = cx.spawn(async move |this, cx| {
             cx.background_executor()
                 .timer(REGENERATE_ON_EDIT_DEBOUNCE_INTERVAL)

crates/go_to_line/src/cursor_position.rs 🔗

@@ -1,4 +1,4 @@
-use editor::{Editor, MultiBufferSnapshot};
+use editor::{Editor, EditorEvent, MultiBufferSnapshot};
 use gpui::{App, Entity, FocusHandle, Focusable, Styled, Subscription, Task, WeakEntity};
 use settings::Settings;
 use std::{fmt::Write, num::NonZeroU32, time::Duration};
@@ -81,7 +81,7 @@ impl CursorPosition {
 
     fn update_position(
         &mut self,
-        editor: Entity<Editor>,
+        editor: &Entity<Editor>,
         debounce: Option<Duration>,
         window: &mut Window,
         cx: &mut Context<Self>,
@@ -269,19 +269,21 @@ impl StatusItemView for CursorPosition {
         cx: &mut Context<Self>,
     ) {
         if let Some(editor) = active_pane_item.and_then(|item| item.act_as::<Editor>(cx)) {
-            self._observe_active_editor =
-                Some(
-                    cx.observe_in(&editor, window, |cursor_position, editor, window, cx| {
-                        Self::update_position(
-                            cursor_position,
-                            editor,
-                            Some(UPDATE_DEBOUNCE),
-                            window,
-                            cx,
-                        )
-                    }),
-                );
-            self.update_position(editor, None, window, cx);
+            self._observe_active_editor = Some(cx.subscribe_in(
+                &editor,
+                window,
+                |cursor_position, editor, event, window, cx| match event {
+                    EditorEvent::SelectionsChanged { .. } => Self::update_position(
+                        cursor_position,
+                        editor,
+                        Some(UPDATE_DEBOUNCE),
+                        window,
+                        cx,
+                    ),
+                    _ => {}
+                },
+            ));
+            self.update_position(&editor, None, window, cx);
         } else {
             self.position = None;
             self._observe_active_editor = None;

crates/gpui/src/app/async_context.rs 🔗

@@ -176,7 +176,7 @@ impl AsyncApp {
         lock.open_window(options, build_root_view)
     }
 
-    /// Schedule a future to be polled in the background.
+    /// Schedule a future to be polled in the foreground.
     #[track_caller]
     pub fn spawn<AsyncFn, R>(&self, f: AsyncFn) -> Task<R>
     where

crates/gpui/src/executor.rs 🔗

@@ -479,7 +479,6 @@ impl ForegroundExecutor {
     }
 
     /// Enqueues the given Task to run on the main thread at some point in the future.
-    #[track_caller]
     pub fn spawn<R>(&self, future: impl Future<Output = R> + 'static) -> Task<R>
     where
         R: 'static,

crates/language/src/buffer.rs 🔗

@@ -1573,21 +1573,24 @@ impl Buffer {
                 self.reparse = None;
             }
             Err(parse_task) => {
+                // todo(lw): hot foreground spawn
                 self.reparse = Some(cx.spawn(async move |this, cx| {
-                    let new_syntax_map = parse_task.await;
+                    let new_syntax_map = cx.background_spawn(parse_task).await;
                     this.update(cx, move |this, cx| {
-                        let grammar_changed =
+                        let grammar_changed = || {
                             this.language.as_ref().is_none_or(|current_language| {
                                 !Arc::ptr_eq(&language, current_language)
-                            });
-                        let language_registry_changed = new_syntax_map
-                            .contains_unknown_injections()
-                            && language_registry.is_some_and(|registry| {
-                                registry.version() != new_syntax_map.language_registry_version()
-                            });
-                        let parse_again = language_registry_changed
-                            || grammar_changed
-                            || this.version.changed_since(&parsed_version);
+                            })
+                        };
+                        let language_registry_changed = || {
+                            new_syntax_map.contains_unknown_injections()
+                                && language_registry.is_some_and(|registry| {
+                                    registry.version() != new_syntax_map.language_registry_version()
+                                })
+                        };
+                        let parse_again = this.version.changed_since(&parsed_version)
+                            || language_registry_changed()
+                            || grammar_changed();
                         this.did_finish_parsing(new_syntax_map, cx);
                         this.reparse = None;
                         if parse_again {

crates/multi_buffer/src/path_key.rs 🔗

@@ -1,7 +1,7 @@
 use std::{mem, ops::Range, sync::Arc};
 
 use collections::HashSet;
-use gpui::{App, AppContext, Context, Entity, Task};

+use gpui::{App, AppContext, Context, Entity};

 use itertools::Itertools;
 use language::{Buffer, BufferSnapshot};
 use rope::Point;
@@ -117,12 +117,14 @@ impl MultiBuffer {
         buffer: Entity<Buffer>,
         ranges: Vec<Range<text::Anchor>>,
         context_line_count: u32,
-        cx: &mut Context<Self>,

-    ) -> Task<Vec<Range<Anchor>>> {

+        cx: &Context<Self>,

+    ) -> impl Future<Output = Vec<Range<Anchor>>> + use<> {

         let buffer_snapshot = buffer.read(cx).snapshot();
-        cx.spawn(async move |multi_buffer, cx| {

+        let multi_buffer = cx.weak_entity();

+        let mut app = cx.to_async();

+        async move {

             let snapshot = buffer_snapshot.clone();
-            let (excerpt_ranges, new, counts) = cx

+            let (excerpt_ranges, new, counts) = app

                 .background_spawn(async move {
                     let ranges = ranges.into_iter().map(|range| range.to_point(&snapshot));
                     let excerpt_ranges =
@@ -133,7 +135,7 @@ impl MultiBuffer {
                 .await;
 
             multi_buffer
-                .update(cx, move |multi_buffer, cx| {

+                .update(&mut app, move |multi_buffer, cx| {

                     let (ranges, _) = multi_buffer.set_merged_excerpt_ranges_for_path(
                         path_key,
                         buffer,
@@ -147,7 +149,7 @@ impl MultiBuffer {
                 })
                 .ok()
                 .unwrap_or_default()
-        })

+        }

     }
 
     pub(super) fn expand_excerpts_with_paths(

crates/project/src/buffer_store.rs 🔗

@@ -619,29 +619,24 @@ impl LocalBufferStore {
         worktree: Entity<Worktree>,
         cx: &mut Context<BufferStore>,
     ) -> Task<Result<Entity<Buffer>>> {
-        let load_buffer = worktree.update(cx, |worktree, cx| {
-            let load_file = worktree.load_file(path.as_ref(), cx);
-            let reservation = cx.reserve_entity();
-            let buffer_id = BufferId::from(reservation.entity_id().as_non_zero_u64());
-            let path = path.clone();
-            cx.spawn(async move |_, cx| {
-                let loaded = load_file.await.with_context(|| {
-                    format!("Could not open path: {}", path.display(PathStyle::local()))
-                })?;
-                let text_buffer = cx
-                    .background_spawn(async move {
-                        text::Buffer::new(ReplicaId::LOCAL, buffer_id, loaded.text)
-                    })
-                    .await;
-                cx.insert_entity(reservation, |_| {
-                    Buffer::build(text_buffer, Some(loaded.file), Capability::ReadWrite)
-                })
-            })
-        });
-
+        let load_file = worktree.update(cx, |worktree, cx| worktree.load_file(path.as_ref(), cx));
         cx.spawn(async move |this, cx| {
-            let buffer = match load_buffer.await {
-                Ok(buffer) => Ok(buffer),
+            let path = path.clone();
+            let buffer = match load_file.await.with_context(|| {
+                format!("Could not open path: {}", path.display(PathStyle::local()))
+            }) {
+                Ok(loaded) => {
+                    let reservation = cx.reserve_entity::<Buffer>()?;
+                    let buffer_id = BufferId::from(reservation.entity_id().as_non_zero_u64());
+                    let text_buffer = cx
+                        .background_spawn(async move {
+                            text::Buffer::new(ReplicaId::LOCAL, buffer_id, loaded.text)
+                        })
+                        .await;
+                    cx.insert_entity(reservation, |_| {
+                        Buffer::build(text_buffer, Some(loaded.file), Capability::ReadWrite)
+                    })?
+                }
                 Err(error) if is_not_found_error(&error) => cx.new(|cx| {
                     let buffer_id = BufferId::from(cx.entity_id().as_non_zero_u64());
                     let text_buffer = text::Buffer::new(ReplicaId::LOCAL, buffer_id, "");
@@ -657,9 +652,9 @@ impl LocalBufferStore {
                         })),
                         Capability::ReadWrite,
                     )
-                }),
-                Err(e) => Err(e),
-            }?;
+                })?,
+                Err(e) => return Err(e),
+            };
             this.update(cx, |this, cx| {
                 this.add_buffer(buffer.clone(), cx)?;
                 let buffer_id = buffer.read(cx).remote_id();
@@ -840,6 +835,7 @@ impl BufferStore {
 
                 entry
                     .insert(
+                        // todo(lw): hot foreground spawn
                         cx.spawn(async move |this, cx| {
                             let load_result = load_buffer.await;
                             this.update(cx, |this, cx| {

crates/project/src/git_store.rs 🔗

@@ -709,6 +709,7 @@ impl GitStore {
                     repo.load_committed_text(buffer_id, repo_path, cx)
                 });
 
+                // todo(lw): hot foreground spawn
                 cx.spawn(async move |this, cx| {
                     Self::open_diff_internal(this, DiffKind::Uncommitted, changes.await, buffer, cx)
                         .await

crates/project/src/project_tests.rs 🔗

@@ -9171,7 +9171,9 @@ async fn test_odd_events_for_ignored_dirs(
         repository_updates.lock().drain(..).collect::<Vec<_>>(),
         vec![
             RepositoryEvent::MergeHeadsChanged,
-            RepositoryEvent::BranchChanged
+            RepositoryEvent::BranchChanged,
+            RepositoryEvent::StatusesChanged { full_scan: false },
+            RepositoryEvent::StatusesChanged { full_scan: false },
         ],
         "Initial worktree scan should produce a repo update event"
     );

crates/search/src/project_search.rs 🔗

@@ -322,18 +322,25 @@ impl ProjectSearch {
 
             let mut limit_reached = false;
             while let Some(results) = matches.next().await {
-                let mut buffers_with_ranges = Vec::with_capacity(results.len());
-                for result in results {
-                    match result {
-                        project::search::SearchResult::Buffer { buffer, ranges } => {
-                            buffers_with_ranges.push((buffer, ranges));
-                        }
-                        project::search::SearchResult::LimitReached => {
-                            limit_reached = true;
+                let (buffers_with_ranges, has_reached_limit) = cx
+                    .background_executor()
+                    .spawn(async move {
+                        let mut limit_reached = false;
+                        let mut buffers_with_ranges = Vec::with_capacity(results.len());
+                        for result in results {
+                            match result {
+                                project::search::SearchResult::Buffer { buffer, ranges } => {
+                                    buffers_with_ranges.push((buffer, ranges));
+                                }
+                                project::search::SearchResult::LimitReached => {
+                                    limit_reached = true;
+                                }
+                            }
                         }
-                    }
-                }
-
+                        (buffers_with_ranges, limit_reached)
+                    })
+                    .await;
+                limit_reached |= has_reached_limit;
                 let mut new_ranges = project_search
                     .update(cx, |project_search, cx| {
                         project_search.excerpts.update(cx, |excerpts, cx| {
@@ -352,7 +359,6 @@ impl ProjectSearch {
                         })
                     })
                     .ok()?;
-
                 while let Some(new_ranges) = new_ranges.next().await {
                     project_search
                         .update(cx, |project_search, cx| {

crates/worktree/src/worktree.rs 🔗

@@ -1318,7 +1318,8 @@ impl LocalWorktree {
         let entry = self.refresh_entry(path.clone(), None, cx);
         let is_private = self.is_path_private(path.as_ref());
 
-        cx.spawn(async move |this, _cx| {
+        let this = cx.weak_entity();
+        cx.background_spawn(async move {
             // WARN: Temporary workaround for #27283.
             //       We are not efficient with our memory usage per file, and use in excess of 64GB for a 10GB file
             //       Therefore, as a temporary workaround to prevent system freezes, we just bail before opening a file
@@ -1702,6 +1703,7 @@ impl LocalWorktree {
         };
         let t0 = Instant::now();
         let mut refresh = self.refresh_entries_for_paths(paths);
+        // todo(lw): Hot foreground spawn
         cx.spawn(async move |this, cx| {
             refresh.recv().await;
             log::trace!("refreshed entry {path:?} in {:?}", t0.elapsed());

crates/zed/src/zed.rs 🔗

@@ -2860,16 +2860,20 @@ mod tests {
         });
 
         // Split the pane with the first entry, then open the second entry again.
-        let (task1, task2) = window
+        window
             .update(cx, |w, window, cx| {
-                (
-                    w.split_and_clone(w.active_pane().clone(), SplitDirection::Right, window, cx),
-                    w.open_path(file2.clone(), None, true, window, cx),
-                )
+                w.split_and_clone(w.active_pane().clone(), SplitDirection::Right, window, cx)
+            })
+            .unwrap()
+            .await
+            .unwrap();
+        window
+            .update(cx, |w, window, cx| {
+                w.open_path(file2.clone(), None, true, window, cx)
             })
+            .unwrap()
+            .await
             .unwrap();
-        task1.await.unwrap();
-        task2.await.unwrap();
 
         window
             .read_with(cx, |w, cx| {