perf: Reduce default async thread count (#18142)

pola-rs · Aug 12, 2024 · 13ff0e9 · 13ff0e9
1 parent a3eef6d
commit 13ff0e9
Showing 1 changed file with 9 additions and 1 deletion.
diff --git a/crates/polars-io/src/pl_async.rs b/crates/polars-io/src/pl_async.rs
@@ -237,8 +237,16 @@ pub struct RuntimeManager {
 
 impl RuntimeManager {
     fn new() -> Self {
+        let n_threads = std::env::var("POLARS_ASYNC_THREAD_COUNT")
+            .map(|x| x.parse::<usize>().expect("integer"))
+            .unwrap_or((POOL.current_num_threads() / 4).clamp(1, 4));
+
+        if polars_core::config::verbose() {
+            eprintln!("Async thread count: {}", n_threads);
+        }
+
         let rt = Builder::new_multi_thread()
-            .worker_threads(std::cmp::max(POOL.current_num_threads(), 4))
+            .worker_threads(n_threads)
             .enable_io()
             .enable_time()
             .build()