From 4fa6dbb704e8e164943c9d38b85f1884d2f4267b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Yara=20=F0=9F=8F=B3=EF=B8=8F=E2=80=8D=E2=9A=A7=EF=B8=8F?=
 <git@yara.blue>
Date: Fri, 19 Dec 2025 16:03:35 +0100
Subject: [PATCH] adjusted scheduler prioritization algorithm (#45367)

This fixes a number of issues where zed depends on the order of polling which changed when switching scheduler. We have adjusted the algorithm so it matches the previous order while keeping the prioritization feature.

Release Notes:
- N/A
---
 crates/gpui/src/queue.rs | 25 +++++++++++++------------
 1 file changed, 13 insertions(+), 12 deletions(-)

diff --git a/crates/gpui/src/queue.rs b/crates/gpui/src/queue.rs
index 9e9da71097..1ecec183c6 100644
--- a/crates/gpui/src/queue.rs
+++ b/crates/gpui/src/queue.rs
@@ -1,4 +1,5 @@
 use std::{
+    collections::VecDeque,
     fmt,
     iter::FusedIterator,
     sync::{Arc, atomic::AtomicUsize},
@@ -9,9 +10,9 @@ use rand::{Rng, SeedableRng, rngs::SmallRng};
 use crate::Priority;
 
 struct PriorityQueues<T> {
-    high_priority: Vec<T>,
-    medium_priority: Vec<T>,
-    low_priority: Vec<T>,
+    high_priority: VecDeque<T>,
+    medium_priority: VecDeque<T>,
+    low_priority: VecDeque<T>,
 }
 
 impl<T> PriorityQueues<T> {
@@ -42,9 +43,9 @@ impl<T> PriorityQueueState<T> {
         let mut queues = self.queues.lock();
         match priority {
             Priority::Realtime(_) => unreachable!(),
-            Priority::High => queues.high_priority.push(item),
-            Priority::Medium => queues.medium_priority.push(item),
-            Priority::Low => queues.low_priority.push(item),
+            Priority::High => queues.high_priority.push_back(item),
+            Priority::Medium => queues.medium_priority.push_back(item),
+            Priority::Low => queues.low_priority.push_back(item),
         };
         self.condvar.notify_one();
         Ok(())
@@ -141,9 +142,9 @@ impl<T> PriorityQueueReceiver<T> {
     pub(crate) fn new() -> (PriorityQueueSender<T>, Self) {
         let state = PriorityQueueState {
             queues: parking_lot::Mutex::new(PriorityQueues {
-                high_priority: Vec::new(),
-                medium_priority: Vec::new(),
-                low_priority: Vec::new(),
+                high_priority: VecDeque::new(),
+                medium_priority: VecDeque::new(),
+                low_priority: VecDeque::new(),
             }),
             condvar: parking_lot::Condvar::new(),
             receiver_count: AtomicUsize::new(1),
@@ -226,7 +227,7 @@ impl<T> PriorityQueueReceiver<T> {
         if !queues.high_priority.is_empty() {
             let flip = self.rand.random_ratio(P::High.probability(), mass);
             if flip {
-                return Ok(queues.high_priority.pop());
+                return Ok(queues.high_priority.pop_front());
             }
             mass -= P::High.probability();
         }
@@ -234,7 +235,7 @@ impl<T> PriorityQueueReceiver<T> {
         if !queues.medium_priority.is_empty() {
             let flip = self.rand.random_ratio(P::Medium.probability(), mass);
             if flip {
-                return Ok(queues.medium_priority.pop());
+                return Ok(queues.medium_priority.pop_front());
             }
             mass -= P::Medium.probability();
         }
@@ -242,7 +243,7 @@ impl<T> PriorityQueueReceiver<T> {
         if !queues.low_priority.is_empty() {
             let flip = self.rand.random_ratio(P::Low.probability(), mass);
             if flip {
-                return Ok(queues.low_priority.pop());
+                return Ok(queues.low_priority.pop_front());
             }
         }