Agent Eval: bounded concurrency (#28843)

Release Notes:

- N/A

crates/eval/src/eval.rs

@@ -10,6 +10,7 @@ use anyhow::{Result, anyhow};
 use clap::Parser;
 use extension::ExtensionHostProxy;
 use futures::future;
+use futures::stream::StreamExt;
 use gpui::http_client::{Uri, read_proxy_from_env};
 use gpui::{App, AppContext, Application, AsyncApp, Entity, SemanticVersion, Task, UpdateGlobal};
 use gpui_tokio::Tokio;
@@ -46,6 +47,9 @@ struct Args {
     /// How many times to run the judge on each example run.
     #[arg(long, default_value = "3")]
     judge_repetitions: u32,
+    /// Maximum number of examples to run concurrently.
+    #[arg(long, default_value = "10")]
+    concurrency: usize,
 }
 
 fn main() {
@@ -217,22 +221,25 @@ fn main() {
             }
 
             let judge_repetitions = args.judge_repetitions;
+            let concurrency = args.concurrency;
+
             let tasks = examples
                 .into_iter()
                 .map(|example| {
                     let app_state = app_state.clone();
                     let model = model.clone();
                     cx.spawn(async move |cx| {
-                        (
-                            run_example(&example, model, app_state, judge_repetitions, cx).await,
-                            example,
-                        )
+                        let result =
+                            run_example(&example, model, app_state, judge_repetitions, cx).await;
+                        (result, example)
                     })
                 })
                 .collect::<Vec<_>>();
 
-            let results: Vec<(Result<Vec<Result<JudgeOutput>>>, Example)> =
-                future::join_all(tasks).await;
+            let results = futures::stream::iter(tasks)
+                .buffer_unordered(concurrency)
+                .collect::<Vec<(Result<Vec<Result<JudgeOutput>>>, Example)>>()
+                .await;
 
             println!("\n\n");
             println!("========================================");