From 215b1ec2f18bae17028975168005cb268bd43a14 Mon Sep 17 00:00:00 2001
From: Stefan Holderbach <sholderbach@users.noreply.github.com>
Date: Thu, 21 Aug 2025 14:47:31 +0200
Subject: [PATCH] Add a benchmark `use`ing the whole `std` (#16485)

In our benchmark suite for a while (#12025) we had a benchmark that
invoked the `nu-std::load_standard_library` function.
But as we prioritized the startup speed the default behavior is to just
import the prelude and make the modules available for later parsing.

With this added benchmarks the entire library is loaded via `use std`.
This gives us a parsing benchmark with a somewhat diverse set of
constructs that get used. This should be helpful to inspect general
trends when we make changes to the parser or the parts of the engines
relevant during parse time.


## Release notes summary - What our users need to know
N/A
---
 benches/benchmarks.rs | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/benches/benchmarks.rs b/benches/benchmarks.rs
index 1ffb4ccc92..6a25221355 100644
--- a/benches/benchmarks.rs
+++ b/benches/benchmarks.rs
@@ -139,6 +139,30 @@ fn bench_load_standard_lib() -> impl IntoBenchmarks {
     })]
 }
 
+/// Load all modules of standard library into the engine through a general `use`.
+fn bench_load_use_standard_lib() -> impl IntoBenchmarks {
+    [benchmark_fn("load_use_standard_lib", move |b| {
+        // We need additional commands like `format number` for the standard library
+        let engine = nu_cmd_extra::add_extra_command_context(setup_engine());
+        let commands = Spanned {
+            item: "use std".into(),
+            span: Span::unknown(),
+        };
+        b.iter(move || {
+            let mut engine = engine.clone();
+            let mut stack = Stack::new();
+            let _ = load_standard_library(&mut engine);
+            evaluate_commands(
+                &commands,
+                &mut engine,
+                &mut stack,
+                PipelineData::empty(),
+                Default::default(),
+            )
+        })
+    })]
+}
+
 fn create_flat_record_string(n: usize) -> String {
     let mut s = String::from("let record = { ");
     for i in 0..n {
@@ -437,6 +461,7 @@ fn decode_msgpack(row_cnt: usize, col_cnt: usize) -> impl IntoBenchmarks {
 
 tango_benchmarks!(
     bench_load_standard_lib(),
+    bench_load_use_standard_lib(),
     // Data types
     // Record
     bench_record_create(1),