Use the same background executor for spawning CPU intensive tasks

Co-Authored-By: Nathan Sobo <nathan@zed.dev>
Co-Authored-By: Max Brunsfeld <max@zed.dev>

gpui/src/app.rs

@@ -123,7 +123,6 @@ impl App {
         let cx = Rc::new(RefCell::new(MutableAppContext::new(
             foreground,
             Arc::new(executor::Background::new()),
-            Arc::new(executor::Background::new()),
             Arc::new(platform),
             Rc::new(foreground_platform),
             (),
@@ -140,7 +139,6 @@ impl App {
         let app = Self(Rc::new(RefCell::new(MutableAppContext::new(
             foreground,
             Arc::new(executor::Background::new()),
-            Arc::new(executor::Background::new()),
             platform.clone(),
             foreground_platform.clone(),
             asset_source,
@@ -247,7 +245,6 @@ impl TestAppContext {
     pub fn new(
         foreground: Rc<executor::Foreground>,
         background: Arc<executor::Background>,
-        thread_pool: Arc<executor::Background>,
         first_entity_id: usize,
     ) -> Self {
         let platform = Arc::new(platform::test::platform());
@@ -255,7 +252,6 @@ impl TestAppContext {
         let mut cx = MutableAppContext::new(
             foreground.clone(),
             background,
-            thread_pool,
             platform,
             foreground_platform.clone(),
             (),
@@ -594,7 +590,6 @@ impl MutableAppContext {
     fn new(
         foreground: Rc<executor::Foreground>,
         background: Arc<executor::Background>,
-        thread_pool: Arc<executor::Background>,
         platform: Arc<dyn platform::Platform>,
         foreground_platform: Rc<dyn platform::ForegroundPlatform>,
         asset_source: impl AssetSource,
@@ -612,7 +607,6 @@ impl MutableAppContext {
                 values: Default::default(),
                 ref_counts: Arc::new(Mutex::new(RefCounts::default())),
                 background,
-                thread_pool,
                 font_cache: Arc::new(FontCache::new(fonts)),
             },
             actions: HashMap::new(),
@@ -1490,7 +1484,6 @@ pub struct AppContext {
     values: RwLock<HashMap<(TypeId, usize), Box<dyn Any>>>,
     background: Arc<executor::Background>,
     ref_counts: Arc<Mutex<RefCounts>>,
-    thread_pool: Arc<executor::Background>,
     font_cache: Arc<FontCache>,
 }
 
@@ -1535,10 +1528,6 @@ impl AppContext {
         &self.font_cache
     }
 
-    pub fn thread_pool(&self) -> &Arc<executor::Background> {
-        &self.thread_pool
-    }
-
     pub fn value<Tag: 'static, T: 'static + Default>(&self, id: usize) -> ValueHandle<T> {
         let key = (TypeId::of::<Tag>(), id);
         let mut values = self.values.write();
@@ -1721,10 +1710,6 @@ impl<'a, T: Entity> ModelContext<'a, T> {
         &self.app.cx.background
     }
 
-    pub fn thread_pool(&self) -> &Arc<executor::Background> {
-        &self.app.cx.thread_pool
-    }
-
     pub fn halt_stream(&mut self) {
         self.halt_stream = true;
     }

gpui/src/executor.rs

@@ -34,7 +34,6 @@ pub enum Background {
     Deterministic(Arc<Deterministic>),
     Production {
         executor: Arc<smol::Executor<'static>>,
-        threads: usize,
         _stop: channel::Sender<()>,
     },
 }
@@ -324,9 +323,8 @@ impl Background {
     pub fn new() -> Self {
         let executor = Arc::new(Executor::new());
         let stop = channel::unbounded::<()>();
-        let threads = num_cpus::get();
 
-        for i in 0..threads {
+        for i in 0..2 * num_cpus::get() {
             let executor = executor.clone();
             let stop = stop.1.clone();
             thread::Builder::new()
@@ -337,16 +335,12 @@ impl Background {
 
         Self::Production {
             executor,
-            threads,
             _stop: stop.0,
         }
     }
 
-    pub fn threads(&self) -> usize {
-        match self {
-            Self::Deterministic(_) => 1,
-            Self::Production { threads, .. } => *threads,
-        }
+    pub fn num_cpus(&self) -> usize {
+        num_cpus::get()
     }
 
     pub fn spawn<T, F>(&self, future: F) -> Task<T>