Repository: denoland/deno
Pull request: perf(cli): Improve concurrency when setting up `node_modules` and loading cached npm package info

The same issue in two different places - doing blocking FS work in an async task, limiting the amount of work that happens concurrently.

- When setting up node_modules, where we try to set up entries concurrently but were blocking other tasks from actually running.
- When loading package info from the npm registry file cache, loading and deserializing is expensive and prevents concurrency. This was especially noticeable when loading an npm resolution snapshot from a lockfile (`snapshot_from_lockfile` in `deno_npm`).

Installing deps in `deno-docs`:

```
❯ hyperfine -i -p 'rm -rf node_modules/' '../d7/deno-main i' '../d7/target/release/deno i'
Benchmark 1: ../d7/deno-main i
  Time (mean ± σ):      2.193 s ±  0.027 s    [User: 0.589 s, System: 1.033 s]
  Range (min … max):    2.151 s …  2.242 s    10 runs

Benchmark 2: ../d7/target/release/deno i
  Time (mean ± σ):      1.597 s ±  0.021 s    [User: 0.977 s, System: 1.337 s]
  Range (min … max):    1.550 s …  1.627 s    10 runs

Summary
  ../d7/target/release/deno i ran
    1.37 ± 0.02 times faster than ../d7/deno-main i
```

Caching `npm:@11ty/eleventy`:
```
❯ hyperfine -i -p 'rm -rf node_modules/' --warmup 5 '../../d7/deno-main cache npm:@11ty/eleventy' '../../d7/target/release/deno cache npm:@11ty/eleventy'
Benchmark 1: ../../d7/deno-main cache npm:@11ty/eleventy
  Time (mean ± σ):     129.9 ms ±   2.2 ms    [User: 27.5 ms, System: 101.3 ms]
  Range (min … max):   127.5 ms … 135.8 ms    10 runs

Benchmark 2: ../../d7/target/release/deno cache npm:@11ty/eleventy
  Time (mean ± σ):     100.6 ms ±   1.3 ms    [User: 38.8 ms, System: 233.8 ms]
  Range (min … max):    99.3 ms … 103.2 ms    10 runs

Summary
  ../../d7/target/release/deno cache npm:@11ty/eleventy ran
    1.29 ± 0.03 times faster than ../../d7/deno-main cache npm:@11ty/eleventy
```

Changed files:
filename: cli/npm/managed/registry.rs
patch: @@ -142,24 +142,21 @@ impl CliNpmRegistryApiInner {
         }
         Some(CacheItem::Pending(future)) => (false, future.clone()),
         None => {
-          if (self.cache.cache_setting().should_use_for_npm_package(name) && !self.force_reload())
-            // if this has been previously reloaded, then try loading from the
-            // file system cache
-            || !self.previously_reloaded_packages.lock().insert(name.to_string())
-          {
-            // attempt to load from the file cache
-            if let Some(info) = self.load_file_cached_package_info(name) {
-              let result = Some(Arc::new(info));
-              mem_cache
-                .insert(name.to_string(), CacheItem::Resolved(result.clone()));
-              return Ok(result);
-            }
-          }
-
           let future = {
             let api = self.clone();
             let name = name.to_string();
             async move {
+              if (api.cache.cache_setting().should_use_for_npm_package(&name) && !api.force_reload())
+                // if this has been previously reloaded, then try loading from the
+                // file system cache
+                || !api.previously_reloaded_packages.lock().insert(name.to_string())
+              {
+                // attempt to load from the file cache
+                if let Some(info) = api.load_file_cached_package_info(&name).await {
+                  let result = Some(Arc::new(info));
+                  return Ok(result);
+                }
+              }
               api
                 .load_package_info_from_registry(&name)
                 .await
@@ -201,11 +198,11 @@ impl CliNpmRegistryApiInner {
     self.force_reload_flag.is_raised()
   }
 
-  fn load_file_cached_package_info(
+  async fn load_file_cached_package_info(
     &self,
     name: &str,
   ) -> Option<NpmPackageInfo> {
-    match self.load_file_cached_package_info_result(name) {
+    match self.load_file_cached_package_info_result(name).await {
       Ok(value) => value,
       Err(err) => {
         if cfg!(debug_assertions) {
@@ -217,18 +214,25 @@ impl CliNpmRegistryApiInner {
     }
   }
 
-  fn load_file_cached_package_info_result(
+  async fn load_file_cached_package_info_result(
     &self,
     name: &str,
   ) -> Result<Option<NpmPackageInfo>, AnyError> {
     let file_cache_path = self.get_package_file_cache_path(name);
-    let file_text = match fs::read_to_string(file_cache_path) {
-      Ok(file_text) => file_text,
-      Err(err) if err.kind() == ErrorKind::NotFound => return Ok(None),
-      Err(err) => return Err(err.into()),
-    };
-    match serde_json::from_str(&file_text) {
-      Ok(package_info) => Ok(Some(package_info)),
+    let deserialization_result = deno_core::unsync::spawn_blocking(|| {
+      let file_text = match fs::read_to_string(file_cache_path) {
+        Ok(file_text) => file_text,
+        Err(err) if err.kind() == ErrorKind::NotFound => return Ok(None),
+        Err(err) => return Err(err.into()),
+      };
+      serde_json::from_str(&file_text)
+        .map(Some)
+        .map_err(AnyError::from)
+    })
+    .await
+    .unwrap();
+    match deserialization_result {
+      Ok(maybe_package_info) => Ok(maybe_package_info),
       Err(err) => {
         // This scenario might mean we need to load more data from the
         // npm registry than before. So, just debug log while in debug
@@ -317,7 +321,10 @@ impl CliNpmRegistryApiInner {
       .await?;
     match maybe_bytes {
       Some(bytes) => {
-        let package_info = serde_json::from_slice(&bytes)?;
+        let package_info = deno_core::unsync::spawn_blocking(move || {
+          serde_json::from_slice(&bytes)
+        })
+        .await??;
         self.save_package_info_to_file_cache(name, &package_info);
         Ok(Some(package_info))
       }

filename: cli/npm/managed/resolvers/local.rs
patch: @@ -332,9 +332,18 @@ async fn sync_resolution_with_fs(
           join_package_name(&sub_node_modules, &package.id.nv.name);
         let cache_folder =
           cache.package_folder_for_name_and_version(&package.id.nv);
-        clone_dir_recursive(&cache_folder, &package_path)?;
-        // write out a file that indicates this folder has been initialized
-        fs::write(initialized_file, "")?;
+
+        deno_core::unsync::spawn_blocking({
+          let package_path = package_path.clone();
+          move || {
+            clone_dir_recursive(&cache_folder, &package_path)?;
+            // write out a file that indicates this folder has been initialized
+            fs::write(initialized_file, "")?;
+
+            Ok::<_, AnyError>(())
+          }
+        })
+        .await??;
 
         if package.bin.is_some() {
           bin_entries_to_setup
@@ -374,6 +383,7 @@ async fn sync_resolution_with_fs(
           .join("node_modules"),
         &package.id.nv.name,
       );
+
       clone_dir_recursive(&source_path, &package_path)?;
       // write out a file that indicates this folder has been initialized
       fs::write(initialized_file, "")?;