refactor(benchmarks): linter benchmark re-run parsing and semantic on each iteration (#13335)

Refactor linter benchmark so it parses and generates `Semantic` afresh before each measured iteration.

This is more realistic usage - in real world you'd never lint the same file repeatedly - and may make cache utilization in the benchmark more realistic.

It also prepares the way for upcoming changes where `ContextSubHost::new` will take an owned `Semantic` instead of `Rc<Semantic>`.

Author: overlookmotel

tasks/benchmark/benches/linter.rs

@@ -19,32 +19,47 @@ fn bench_linter(criterion: &mut Criterion) {
         let id = BenchmarkId::from_parameter(&file.file_name);
         let source_text = &file.source_text;
         let source_type = file.source_type;
-        let allocator = Allocator::default();
-        let ret = Parser::new(&allocator, source_text, source_type).parse();
-        let path = Path::new("");
-        let semantic_ret = SemanticBuilder::new()
-            .with_build_jsdoc(true)
-            .with_scope_tree_child_ids(true)
-            .with_cfg(true)
-            .build(&ret.program);
-        let semantic = semantic_ret.semantic;
-        let module_record = Arc::new(ModuleRecord::new(path, &ret.module_record, &semantic));
-        let semantic = Rc::new(semantic);
-        let external_plugin_store = ExternalPluginStore::default();
-        let lint_config = ConfigStoreBuilder::all().build(&external_plugin_store).unwrap();
-        let linter = Linter::new(
-            LintOptions::default(),
-            ConfigStore::new(lint_config, FxHashMap::default(), external_plugin_store),
-            None,
-        )
-        .with_fix(FixKind::All);
+
+        // Create `Allocator` outside of `bench_function`, so same allocator is used for
+        // both the warmup and measurement phases
+        let mut allocator = Allocator::default();
+
         group.bench_function(id, |b| {
-            b.iter(|| {
-                linter.run(
-                    path,
-                    vec![ContextSubHost::new(Rc::clone(&semantic), Arc::clone(&module_record), 0)],
-                    &allocator,
+            b.iter_with_setup_wrapper(|runner| {
+                // Reset allocator at start of each iteration
+                allocator.reset();
+
+                let parser_ret = Parser::new(&allocator, source_text, source_type).parse();
+                let path = Path::new("");
+                let semantic_ret = SemanticBuilder::new()
+                    .with_build_jsdoc(true)
+                    .with_scope_tree_child_ids(true)
+                    .with_cfg(true)
+                    .build(&parser_ret.program);
+                let semantic = semantic_ret.semantic;
+                let module_record =
+                    Arc::new(ModuleRecord::new(path, &parser_ret.module_record, &semantic));
+                let semantic = Rc::new(semantic);
+                let external_plugin_store = ExternalPluginStore::default();
+                let lint_config = ConfigStoreBuilder::all().build(&external_plugin_store).unwrap();
+                let linter = Linter::new(
+                    LintOptions::default(),
+                    ConfigStore::new(lint_config, FxHashMap::default(), external_plugin_store),
+                    None,
                 )
+                .with_fix(FixKind::All);
+
+                runner.run(|| {
+                    linter.run(
+                        path,
+                        vec![ContextSubHost::new(
+                            Rc::clone(&semantic),
+                            Arc::clone(&module_record),
+                            0,
+                        )],
+                        &allocator,
+                    )
+                });
             });
         });
     }