refactor(core): bake single-thread assumptions into spawn/spawn_blocking (#19056)

Partially supersedes #19016.

This migrates `spawn` and `spawn_blocking` to `deno_core`, and removes
the requirement for `spawn` tasks to be `Send` given our single-threaded
executor.

While we don't need to technically do anything w/`spawn_blocking`, this
allows us to have a single `JoinHandle` type that works for both cases,
and allows us to more easily experiment with alternative
`spawn_blocking` implementations that do not require tokio (ie: rayon).

Async ops (+~35%):

Before: 

```
time 1310 ms rate 763358
time 1267 ms rate 789265
time 1259 ms rate 794281
time 1266 ms rate 789889
```

After:

```
time 956 ms rate 1046025
time 954 ms rate 1048218
time 924 ms rate 1082251
time 920 ms rate 1086956
```

HTTP serve (+~4.4%):

Before:

```
Running 10s test @ http://localhost:4500
  2 threads and 10 connections
  Thread Stats   Avg      Stdev     Max   +/- Stdev
    Latency    68.78us   19.77us   1.43ms   86.84%
    Req/Sec    68.78k     5.00k   73.84k    91.58%
  1381833 requests in 10.10s, 167.36MB read
Requests/sec: 136823.29
Transfer/sec:     16.57MB
```

After:

```
Running 10s test @ http://localhost:4500
  2 threads and 10 connections
  Thread Stats   Avg      Stdev     Max   +/- Stdev
    Latency    63.12us   17.43us   1.11ms   85.13%
    Req/Sec    71.82k     3.71k   77.02k    79.21%
  1443195 requests in 10.10s, 174.79MB read
Requests/sec: 142921.99
Transfer/sec:     17.31MB
```

Suggested-By: alice@ryhl.io
Co-authored-by: Bartek Iwańczuk <biwanczuk@gmail.com>

cli/cache/cache_db.rs

@@ -3,6 +3,7 @@
 use deno_core::error::AnyError;
 use deno_core::parking_lot::Mutex;
 use deno_core::parking_lot::MutexGuard;
+use deno_core::task::spawn_blocking;
 use deno_runtime::deno_webstorage::rusqlite;
 use deno_runtime::deno_webstorage::rusqlite::Connection;
 use deno_runtime::deno_webstorage::rusqlite::OptionalExtension;
@@ -95,7 +96,7 @@ impl Drop for CacheDB {
       // Hand off SQLite connection to another thread to do the surprisingly expensive cleanup
       let inner = inner.into_inner().into_inner();
       if let Some(conn) = inner {
-        tokio::task::spawn_blocking(move || {
+        spawn_blocking(move || {
           drop(conn);
           log::trace!(
             "Cleaned up SQLite connection at {}",
@@ -168,7 +169,7 @@ impl CacheDB {
   fn spawn_eager_init_thread(&self) {
     let clone = self.clone();
     debug_assert!(tokio::runtime::Handle::try_current().is_ok());
-    tokio::task::spawn_blocking(move || {
+    spawn_blocking(move || {
       let lock = clone.conn.lock();
       clone.initialize(&lock);
     });

cli/cache/incremental.rs

@@ -7,9 +7,10 @@ use std::path::PathBuf;
 use deno_core::error::AnyError;
 use deno_core::parking_lot::Mutex;
 use deno_core::serde_json;
+use deno_core::task::spawn;
+use deno_core::task::JoinHandle;
 use deno_runtime::deno_webstorage::rusqlite::params;
 use serde::Serialize;
-use tokio::task::JoinHandle;
 
 use super::cache_db::CacheDB;
 use super::cache_db::CacheDBConfiguration;
@@ -93,7 +94,7 @@ impl IncrementalCacheInner {
       tokio::sync::mpsc::unbounded_channel::<ReceiverMessage>();
 
     // sqlite isn't `Sync`, so we do all the updating on a dedicated task
-    let handle = tokio::task::spawn(async move {
+    let handle = spawn(async move {
       while let Some(message) = receiver.recv().await {
         match message {
           ReceiverMessage::Update(path, hash) => {

cli/lsp/client.rs

@@ -8,6 +8,7 @@ use deno_core::anyhow::bail;
 use deno_core::error::AnyError;
 use deno_core::serde_json;
 use deno_core::serde_json::Value;
+use deno_core::task::spawn;
 use tower_lsp::lsp_types as lsp;
 use tower_lsp::lsp_types::ConfigurationItem;
 
@@ -56,7 +57,7 @@ impl Client {
   ) {
     // do on a task in case the caller currently is in the lsp lock
     let client = self.0.clone();
-    tokio::task::spawn(async move {
+    spawn(async move {
       client.send_registry_state_notification(params).await;
     });
   }
@@ -64,7 +65,7 @@ impl Client {
   pub fn send_test_notification(&self, params: TestingNotification) {
     // do on a task in case the caller currently is in the lsp lock
     let client = self.0.clone();
-    tokio::task::spawn(async move {
+    spawn(async move {
       client.send_test_notification(params).await;
     });
   }
@@ -77,7 +78,7 @@ impl Client {
     // do on a task in case the caller currently is in the lsp lock
     let client = self.0.clone();
     let message = message.to_string();
-    tokio::task::spawn(async move {
+    spawn(async move {
       client.show_message(message_type, message).await;
     });
   }

cli/lsp/diagnostics.rs

@@ -25,6 +25,8 @@ use deno_core::resolve_url;
 use deno_core::serde::Deserialize;
 use deno_core::serde_json;
 use deno_core::serde_json::json;
+use deno_core::task::spawn;
+use deno_core::task::JoinHandle;
 use deno_core::ModuleSpecifier;
 use deno_graph::Resolution;
 use deno_graph::ResolutionError;
@@ -197,9 +199,9 @@ impl DiagnosticsServer {
 
       runtime.block_on(async {
         let mut token = CancellationToken::new();
-        let mut ts_handle: Option<tokio::task::JoinHandle<()>> = None;
+        let mut ts_handle: Option<JoinHandle<()>> = None;
-        let mut lint_handle: Option<tokio::task::JoinHandle<()>> = None;
+        let mut lint_handle: Option<JoinHandle<()>> = None;
-        let mut deps_handle: Option<tokio::task::JoinHandle<()>> = None;
+        let mut deps_handle: Option<JoinHandle<()>> = None;
         let diagnostics_publisher = DiagnosticsPublisher::new(client.clone());
 
         loop {
@@ -213,7 +215,7 @@ impl DiagnosticsServer {
               diagnostics_publisher.clear().await;
 
               let previous_ts_handle = ts_handle.take();
-              ts_handle = Some(tokio::spawn({
+              ts_handle = Some(spawn({
                 let performance = performance.clone();
                 let diagnostics_publisher = diagnostics_publisher.clone();
                 let ts_server = ts_server.clone();
@@ -265,7 +267,7 @@ impl DiagnosticsServer {
               }));
 
               let previous_deps_handle = deps_handle.take();
-              deps_handle = Some(tokio::spawn({
+              deps_handle = Some(spawn({
                 let performance = performance.clone();
                 let diagnostics_publisher = diagnostics_publisher.clone();
                 let token = token.clone();
@@ -293,7 +295,7 @@ impl DiagnosticsServer {
               }));
 
               let previous_lint_handle = lint_handle.take();
-              lint_handle = Some(tokio::spawn({
+              lint_handle = Some(spawn({
                 let performance = performance.clone();
                 let diagnostics_publisher = diagnostics_publisher.clone();
                 let token = token.clone();

cli/lsp/language_server.rs

@@ -8,6 +8,7 @@ use deno_core::resolve_url;
 use deno_core::serde_json;
 use deno_core::serde_json::json;
 use deno_core::serde_json::Value;
+use deno_core::task::spawn;
 use deno_core::ModuleSpecifier;
 use deno_runtime::deno_fs;
 use deno_runtime::deno_node::NodeResolver;
@@ -240,7 +241,7 @@ impl LanguageServer {
           let cli_options = result.cli_options;
           let roots = result.roots;
           let open_docs = result.open_docs;
-          let handle = tokio::task::spawn_local(async move {
+          let handle = spawn(async move {
             create_graph_for_caching(cli_options, roots, open_docs).await
           });
           if let Err(err) = handle.await.unwrap() {

cli/lsp/parent_process_checker.rs

@@ -1,5 +1,6 @@
 // Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
 
+use deno_core::task::spawn;
 use tokio::time::sleep;
 use tokio::time::Duration;
 
@@ -7,7 +8,7 @@ use tokio::time::Duration;
 /// provided process id. Once that process no longer exists
 /// it will terminate the current process.
 pub fn start(parent_process_id: u32) {
-  tokio::task::spawn(async move {
+  spawn(async move {
     loop {
       sleep(Duration::from_secs(30)).await;
 

cli/lsp/testing/execution.rs

@@ -24,9 +24,11 @@ use deno_core::futures::stream;
 use deno_core::futures::StreamExt;
 use deno_core::parking_lot::Mutex;
 use deno_core::parking_lot::RwLock;
+use deno_core::task::spawn;
+use deno_core::task::spawn_blocking;
 use deno_core::ModuleSpecifier;
 use deno_runtime::permissions::Permissions;
-use deno_runtime::tokio_util::run_local;
+use deno_runtime::tokio_util::create_and_run_current_thread;
 use indexmap::IndexMap;
 use std::collections::HashMap;
 use std::collections::HashSet;
@@ -284,7 +286,7 @@ impl TestRun {
       };
       let token = self.token.clone();
 
-      tokio::task::spawn_blocking(move || {
+      spawn_blocking(move || {
         if fail_fast_tracker.should_stop() {
           return Ok(());
         }
@@ -292,13 +294,13 @@ impl TestRun {
         let file_result = if token.is_cancelled() {
           Ok(())
         } else {
-          run_local(test::test_specifier(
+          create_and_run_current_thread(test::test_specifier(
-            &worker_factory,
+            worker_factory,
             permissions,
             specifier,
             sender.clone(),
             fail_fast_tracker,
-            &test::TestSpecifierOptions {
+            test::TestSpecifierOptions {
               filter,
               shuffle: None,
               trace_ops: false,
@@ -331,7 +333,7 @@ impl TestRun {
     ));
 
     let handler = {
-      tokio::task::spawn(async move {
+      spawn(async move {
         let earlier = Instant::now();
         let mut summary = test::TestSummary::new();
         let mut used_only = false;

cli/main.rs

@@ -46,7 +46,7 @@ use deno_core::error::AnyError;
 use deno_core::error::JsError;
 use deno_runtime::colors;
 use deno_runtime::fmt_errors::format_js_error;
-use deno_runtime::tokio_util::run_local;
+use deno_runtime::tokio_util::create_and_run_current_thread;
 use factory::CliFactory;
 use std::env;
 use std::env::current_exe;
@@ -294,7 +294,7 @@ pub fn main() {
     run_subcommand(flags).await
   };
 
-  let exit_code = unwrap_or_exit(run_local(future));
+  let exit_code = unwrap_or_exit(create_and_run_current_thread(future));
 
   std::process::exit(exit_code);
 }

cli/npm/resolvers/common.rs

@@ -9,6 +9,7 @@ use async_trait::async_trait;
 use deno_ast::ModuleSpecifier;
 use deno_core::error::AnyError;
 use deno_core::futures;
+use deno_core::task::spawn;
 use deno_core::url::Url;
 use deno_npm::NpmPackageId;
 use deno_npm::NpmResolutionPackage;
@@ -71,7 +72,7 @@ pub async fn cache_packages(
     assert_eq!(package.copy_index, 0); // the caller should not provide any of these
     let cache = cache.clone();
     let registry_url = registry_url.clone();
-    let handle = tokio::task::spawn(async move {
+    let handle = spawn(async move {
       cache
         .ensure_package(&package.pkg_id.nv, &package.dist, &registry_url)
         .await

cli/npm/resolvers/local.rs

@@ -18,6 +18,8 @@ use deno_ast::ModuleSpecifier;
 use deno_core::anyhow::bail;
 use deno_core::anyhow::Context;
 use deno_core::error::AnyError;
+use deno_core::task::spawn;
+use deno_core::task::JoinHandle;
 use deno_core::url::Url;
 use deno_npm::resolution::NpmResolutionSnapshot;
 use deno_npm::NpmPackageCacheFolderId;
@@ -27,7 +29,6 @@ use deno_runtime::deno_fs;
 use deno_runtime::deno_node::NodePermissions;
 use deno_runtime::deno_node::NodeResolutionMode;
 use deno_runtime::deno_node::PackageJson;
-use tokio::task::JoinHandle;
 
 use crate::npm::cache::mixed_case_package_name_encode;
 use crate::npm::cache::should_sync_download;
@@ -277,7 +278,7 @@ async fn sync_resolution_with_fs(
       let cache = cache.clone();
       let registry_url = registry_url.clone();
       let package = package.clone();
-      let handle = tokio::task::spawn(async move {
+      let handle = spawn(async move {
         cache
           .ensure_package(&package.pkg_id.nv, &package.dist, &registry_url)
           .await?;

cli/tests/integration/cert_tests.rs

@@ -11,7 +11,6 @@ use std::process::Command;
 use std::sync::Arc;
 use test_util as util;
 use test_util::TempDir;
-use tokio::task::LocalSet;
 use util::TestContext;
 
 itest_flaky!(cafile_url_imports {
@@ -219,10 +218,6 @@ fn cafile_bundle_remote_exports() {
 
 #[tokio::test]
 async fn listen_tls_alpn() {
-  // TLS streams require the presence of an ambient local task set to gracefully
-  // close dropped connections in the background.
-  LocalSet::new()
-    .run_until(async {
   let mut child = util::deno_cmd()
     .current_dir(util::testdata_path())
     .arg("run")
@@ -259,8 +254,7 @@ async fn listen_tls_alpn() {
   let tcp_stream = tokio::net::TcpStream::connect("localhost:4504")
     .await
     .unwrap();
-      let mut tls_stream =
+  let mut tls_stream = TlsStream::new_client_side(tcp_stream, cfg, hostname);
-        TlsStream::new_client_side(tcp_stream, cfg, hostname);
 
   tls_stream.handshake().await.unwrap();
 
@@ -270,16 +264,10 @@ async fn listen_tls_alpn() {
 
   let status = child.wait().unwrap();
   assert!(status.success());
-    })
-    .await;
 }
 
 #[tokio::test]
 async fn listen_tls_alpn_fail() {
-  // TLS streams require the presence of an ambient local task set to gracefully
-  // close dropped connections in the background.
-  LocalSet::new()
-    .run_until(async {
   let mut child = util::deno_cmd()
     .current_dir(util::testdata_path())
     .arg("run")
@@ -316,8 +304,7 @@ async fn listen_tls_alpn_fail() {
   let tcp_stream = tokio::net::TcpStream::connect("localhost:4505")
     .await
     .unwrap();
-      let mut tls_stream =
+  let mut tls_stream = TlsStream::new_client_side(tcp_stream, cfg, hostname);
-        TlsStream::new_client_side(tcp_stream, cfg, hostname);
 
   tls_stream.handshake().await.unwrap_err();
 
@@ -326,6 +313,4 @@ async fn listen_tls_alpn_fail() {
 
   let status = child.wait().unwrap();
   assert!(status.success());
-    })
-    .await;
 }

cli/tests/integration/inspector_tests.rs

@@ -29,7 +29,7 @@ where
   Fut::Output: Send + 'static,
 {
   fn execute(&self, fut: Fut) {
-    tokio::task::spawn(fut);
+    deno_core::task::spawn(fut);
   }
 }
 

cli/tests/integration/run_tests.rs

@@ -9,7 +9,6 @@ use std::process::Stdio;
 use std::time::Duration;
 use test_util as util;
 use test_util::TempDir;
-use tokio::task::LocalSet;
 use trust_dns_client::serialize::txt::Lexer;
 use trust_dns_client::serialize::txt::Parser;
 use util::assert_contains;
@@ -3886,10 +3885,6 @@ async fn test_resolve_dns() {
 
 #[tokio::test]
 async fn http2_request_url() {
-  // TLS streams require the presence of an ambient local task set to gracefully
-  // close dropped connections in the background.
-  LocalSet::new()
-    .run_until(async {
   let mut child = util::deno_cmd()
     .current_dir(util::testdata_path())
     .arg("run")
@@ -3928,8 +3923,6 @@ async fn http2_request_url() {
 
   child.kill().unwrap();
   child.wait().unwrap();
-    })
-    .await;
 }
 
 #[cfg(not(windows))]
@@ -4173,7 +4166,7 @@ where
   Fut::Output: Send + 'static,
 {
   fn execute(&self, fut: Fut) {
-    tokio::task::spawn(fut);
+    deno_core::task::spawn(fut);
   }
 }
 

cli/tools/bench.rs

@@ -27,11 +27,13 @@ use deno_core::futures::FutureExt;
 use deno_core::futures::StreamExt;
 use deno_core::located_script_name;
 use deno_core::serde_v8;
+use deno_core::task::spawn;
+use deno_core::task::spawn_blocking;
 use deno_core::v8;
 use deno_core::ModuleSpecifier;
 use deno_runtime::permissions::Permissions;
 use deno_runtime::permissions::PermissionsContainer;
-use deno_runtime::tokio_util::run_local;
+use deno_runtime::tokio_util::create_and_run_current_thread;
 use indexmap::IndexMap;
 use indexmap::IndexSet;
 use log::Level;
@@ -436,7 +438,7 @@ async fn check_specifiers(
 
 /// Run a single specifier as an executable bench module.
 async fn bench_specifier(
-  worker_factory: &CliMainWorkerFactory,
+  worker_factory: Arc<CliMainWorkerFactory>,
   permissions: Permissions,
   specifier: ModuleSpecifier,
   sender: UnboundedSender<BenchEvent>,
@@ -522,15 +524,15 @@ async fn bench_specifiers(
     let specifier = specifier;
     let sender = sender.clone();
     let options = option_for_handles.clone();
-    tokio::task::spawn_blocking(move || {
+    spawn_blocking(move || {
       let future = bench_specifier(
-        &worker_factory,
+        worker_factory,
         permissions,
         specifier,
         sender,
         options.filter,
       );
-      run_local(future)
+      create_and_run_current_thread(future)
     })
   });
 
@@ -539,7 +541,7 @@ async fn bench_specifiers(
     .collect::<Vec<Result<Result<(), AnyError>, tokio::task::JoinError>>>();
 
   let handler = {
-    tokio::task::spawn(async move {
+    spawn(async move {
       let mut used_only = false;
       let mut report = BenchReport::new();
       let mut reporter =

cli/tools/fmt.rs

@@ -28,6 +28,7 @@ use deno_core::error::generic_error;
 use deno_core::error::AnyError;
 use deno_core::futures;
 use deno_core::parking_lot::Mutex;
+use deno_core::task::spawn_blocking;
 use log::debug;
 use log::info;
 use log::warn;
@@ -629,7 +630,7 @@ where
   let handles = file_paths.iter().map(|file_path| {
     let f = f.clone();
     let file_path = file_path.clone();
-    tokio::task::spawn_blocking(move || f(file_path))
+    spawn_blocking(move || f(file_path))
   });
   let join_results = futures::future::join_all(handles).await;
 

cli/tools/repl/mod.rs

@@ -8,6 +8,7 @@ use crate::factory::CliFactory;
 use crate::file_fetcher::FileFetcher;
 use deno_core::error::AnyError;
 use deno_core::futures::StreamExt;
+use deno_core::task::spawn_blocking;
 use deno_runtime::permissions::Permissions;
 use deno_runtime::permissions::PermissionsContainer;
 use rustyline::error::ReadlineError;
@@ -32,7 +33,7 @@ async fn read_line_and_poll(
   editor: ReplEditor,
 ) -> Result<String, ReadlineError> {
   #![allow(clippy::await_holding_refcell_ref)]
-  let mut line_fut = tokio::task::spawn_blocking(move || editor.readline());
+  let mut line_fut = spawn_blocking(move || editor.readline());
   let mut poll_worker = true;
   let notifications_rc = repl_session.notifications.clone();
   let mut notifications = notifications_rc.borrow_mut();

cli/tools/task.rs

@@ -21,6 +21,7 @@ use indexmap::IndexMap;
 use std::collections::HashMap;
 use std::path::PathBuf;
 use std::rc::Rc;
+use tokio::task::LocalSet;
 
 pub async fn execute_script(
   flags: Flags,
@@ -59,9 +60,10 @@ pub async fn execute_script(
     let seq_list = deno_task_shell::parser::parse(&script)
       .with_context(|| format!("Error parsing script '{task_name}'."))?;
     let env_vars = collect_env_vars();
-    let exit_code =
+    let local = LocalSet::new();
-      deno_task_shell::execute(seq_list, env_vars, &cwd, Default::default())
+    let future =
-        .await;
+      deno_task_shell::execute(seq_list, env_vars, &cwd, Default::default());
+    let exit_code = local.run_until(future).await;
     Ok(exit_code)
   } else if let Some(script) = package_json_scripts.get(task_name) {
     let package_json_deps_provider = factory.package_json_deps_provider();
@@ -109,8 +111,10 @@ pub async fn execute_script(
       .with_context(|| format!("Error parsing script '{task_name}'."))?;
     let npx_commands = resolve_npm_commands(npm_resolver, node_resolver)?;
     let env_vars = collect_env_vars();
-    let exit_code =
+    let local = LocalSet::new();
-      deno_task_shell::execute(seq_list, env_vars, &cwd, npx_commands).await;
+    let future =
+      deno_task_shell::execute(seq_list, env_vars, &cwd, npx_commands);
+    let exit_code = local.run_until(future).await;
     Ok(exit_code)
   } else {
     eprintln!("Task not found: {task_name}");

cli/tools/test.rs

@@ -34,6 +34,8 @@ use deno_core::futures::StreamExt;
 use deno_core::located_script_name;
 use deno_core::parking_lot::Mutex;
 use deno_core::serde_v8;
+use deno_core::task::spawn;
+use deno_core::task::spawn_blocking;
 use deno_core::url::Url;
 use deno_core::v8;
 use deno_core::ModuleSpecifier;
@@ -42,7 +44,7 @@ use deno_runtime::deno_io::StdioPipe;
 use deno_runtime::fmt_errors::format_js_error;
 use deno_runtime::permissions::Permissions;
 use deno_runtime::permissions::PermissionsContainer;
-use deno_runtime::tokio_util::run_local;
+use deno_runtime::tokio_util::create_and_run_current_thread;
 use indexmap::IndexMap;
 use indexmap::IndexSet;
 use log::Level;
@@ -916,12 +918,12 @@ pub fn format_test_error(js_error: &JsError) -> String {
 /// Test a single specifier as documentation containing test programs, an executable test module or
 /// both.
 pub async fn test_specifier(
-  worker_factory: &CliMainWorkerFactory,
+  worker_factory: Arc<CliMainWorkerFactory>,
   permissions: Permissions,
   specifier: ModuleSpecifier,
   mut sender: TestEventSender,
   fail_fast_tracker: FailFastTracker,
-  options: &TestSpecifierOptions,
+  options: TestSpecifierOptions,
 ) -> Result<(), AnyError> {
   if fail_fast_tracker.should_stop() {
     return Ok(());
@@ -1316,7 +1318,7 @@ async fn test_specifiers(
   let concurrent_jobs = options.concurrent_jobs;
 
   let sender_ = sender.downgrade();
-  let sigint_handler_handle = tokio::task::spawn(async move {
+  let sigint_handler_handle = spawn(async move {
     signal::ctrl_c().await.unwrap();
     sender_.upgrade().map(|s| s.send(TestEvent::Sigint).ok());
   });
@@ -1328,14 +1330,14 @@ async fn test_specifiers(
     let sender = sender.clone();
     let fail_fast_tracker = FailFastTracker::new(options.fail_fast);
     let specifier_options = options.specifier.clone();
-    tokio::task::spawn_blocking(move || {
+    spawn_blocking(move || {
-      run_local(test_specifier(
+      create_and_run_current_thread(test_specifier(
-        &worker_factory,
+        worker_factory,
         permissions,
         specifier,
         sender.clone(),
         fail_fast_tracker,
-        &specifier_options,
+        specifier_options,
       ))
     })
   });
@@ -1350,7 +1352,7 @@ async fn test_specifiers(
   ));
 
   let handler = {
-    tokio::task::spawn(async move {
+    spawn(async move {
       let earlier = Instant::now();
       let mut tests = IndexMap::new();
       let mut test_steps = IndexMap::new();
@@ -1887,7 +1889,7 @@ pub async fn run_tests_with_watch(
   // run, a process-scoped basic exit handler is required due to a tokio
   // limitation where it doesn't unbind its own handler for the entire process
   // once a user adds one.
-  tokio::task::spawn(async move {
+  spawn(async move {
     loop {
       signal::ctrl_c().await.unwrap();
       if !HAS_TEST_RUN_SIGINT_HANDLER.load(Ordering::Relaxed) {
@@ -2070,7 +2072,7 @@ fn start_output_redirect_thread(
   sender: UnboundedSender<TestEvent>,
   flush_state: Arc<Mutex<Option<std::sync::mpsc::Sender<()>>>>,
 ) {
-  tokio::task::spawn_blocking(move || loop {
+  spawn_blocking(move || loop {
     let mut buffer = [0; 512];
     let size = match pipe_reader.read(&mut buffer) {
       Ok(0) | Err(_) => break,

cli/tools/upgrade.rs

@@ -17,6 +17,7 @@ use deno_core::anyhow::Context;
 use deno_core::error::AnyError;
 use deno_core::futures::future::BoxFuture;
 use deno_core::futures::FutureExt;
+use deno_core::task::spawn;
 use deno_semver::Version;
 use once_cell::sync::Lazy;
 use std::borrow::Cow;
@@ -198,7 +199,7 @@ pub fn check_for_upgrades(
   if update_checker.should_check_for_new_version() {
     let env = update_checker.env.clone();
     // do this asynchronously on a separate task
-    tokio::spawn(async move {
+    spawn(async move {
       // Sleep for a small amount of time to not unnecessarily impact startup
       // time.
       tokio::time::sleep(UPGRADE_CHECK_FETCH_DELAY).await;

cli/util/draw_thread.rs

@@ -2,6 +2,7 @@
 
 use console_static_text::ConsoleStaticText;
 use deno_core::parking_lot::Mutex;
+use deno_core::task::spawn_blocking;
 use deno_runtime::ops::tty::ConsoleSize;
 use once_cell::sync::Lazy;
 use std::sync::Arc;
@@ -162,7 +163,7 @@ impl DrawThread {
     internal_state.has_draw_thread = true;
 
     let drawer_id = internal_state.drawer_id;
-    tokio::task::spawn_blocking(move || {
+    spawn_blocking(move || {
       let mut previous_size = console_size();
       loop {
         let mut delay_ms = 120;

cli/util/fs.rs

@@ -3,6 +3,7 @@
 use deno_core::anyhow::Context;
 use deno_core::error::AnyError;
 pub use deno_core::normalize_path;
+use deno_core::task::spawn_blocking;
 use deno_core::ModuleSpecifier;
 use deno_runtime::deno_crypto::rand;
 use deno_runtime::deno_node::PathClean;
@@ -503,7 +504,7 @@ impl LaxSingleProcessFsFlag {
               // This uses a blocking task because we use a single threaded
               // runtime and this is time sensitive so we don't want it to update
               // at the whims of of whatever is occurring on the runtime thread.
-              tokio::task::spawn_blocking({
+              spawn_blocking({
                 let token = token.clone();
                 let last_updated_path = last_updated_path.clone();
                 move || {

core/Cargo.toml

@@ -36,6 +36,7 @@ serde_json = { workspace = true, features = ["preserve_order"] }
 serde_v8.workspace = true
 smallvec.workspace = true
 sourcemap = "6.1"
+tokio.workspace = true
 url.workspace = true
 v8.workspace = true
 
@@ -46,4 +47,3 @@ path = "examples/http_bench_json_ops/main.rs"
 # These dependencies are only used for the 'http_bench_*_ops' examples.
 [dev-dependencies]
 deno_ast.workspace = true
-tokio.workspace = true

core/lib.rs

@@ -23,6 +23,7 @@ mod resources;
 mod runtime;
 pub mod snapshot_util;
 mod source_map;
+pub mod task;
 mod task_queue;
 
 // Re-exports

core/task.rs

@@ -0,0 +1,131 @@
+// Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
+use core::pin::Pin;
+use core::task::Context;
+use core::task::Poll;
+use futures::Future;
+use std::marker::PhantomData;
+use tokio::runtime::Handle;
+use tokio::runtime::RuntimeFlavor;
+
+/// Equivalent to [`tokio::task::JoinHandle`].
+#[repr(transparent)]
+pub struct JoinHandle<R> {
+  handle: tokio::task::JoinHandle<MaskResultAsSend<R>>,
+  _r: PhantomData<R>,
+}
+
+impl<R> JoinHandle<R> {
+  /// Equivalent to [`tokio::task::JoinHandle::abort`].
+  pub fn abort(&self) {
+    self.handle.abort()
+  }
+}
+
+impl<R> Future for JoinHandle<R> {
+  type Output = Result<R, tokio::task::JoinError>;
+
+  fn poll(
+    self: Pin<&mut Self>,
+    cx: &mut std::task::Context<'_>,
+  ) -> std::task::Poll<Self::Output> {
+    // SAFETY: We are sure that handle is valid here
+    unsafe {
+      let me: &mut Self = Pin::into_inner_unchecked(self);
+      let handle = Pin::new_unchecked(&mut me.handle);
+      match handle.poll(cx) {
+        Poll::Pending => Poll::Pending,
+        Poll::Ready(Ok(r)) => Poll::Ready(Ok(r.into_inner())),
+        Poll::Ready(Err(e)) => Poll::Ready(Err(e)),
+      }
+    }
+  }
+}
+
+/// Equivalent to [`tokio::task::spawn`], but does not require the future to be [`Send`]. Must only be
+/// used on a [`RuntimeFlavor::CurrentThread`] executor, though this is only checked when running with
+/// debug assertions.
+pub fn spawn<F: Future<Output = R> + 'static, R: 'static>(
+  f: F,
+) -> JoinHandle<R> {
+  debug_assert!(
+    Handle::current().runtime_flavor() == RuntimeFlavor::CurrentThread
+  );
+  // SAFETY: we know this is a current-thread executor
+  let future = unsafe { MaskFutureAsSend::new(f) };
+  JoinHandle {
+    handle: tokio::task::spawn(future),
+    _r: Default::default(),
+  }
+}
+
+/// Equivalent to [`tokio::task::spawn_blocking`]. Currently a thin wrapper around the tokio API, but this
+/// may change in the future.
+pub fn spawn_blocking<
+  F: (FnOnce() -> R) + Send + 'static,
+  R: Send + 'static,
+>(
+  f: F,
+) -> JoinHandle<R> {
+  let handle = tokio::task::spawn_blocking(|| MaskResultAsSend { result: f() });
+  JoinHandle {
+    handle,
+    _r: Default::default(),
+  }
+}
+
+#[repr(transparent)]
+#[doc(hidden)]
+pub struct MaskResultAsSend<R> {
+  result: R,
+}
+
+/// SAFETY: We ensure that Send bounds are only faked when tokio is running on a current-thread executor
+unsafe impl<R> Send for MaskResultAsSend<R> {}
+
+impl<R> MaskResultAsSend<R> {
+  #[inline(always)]
+  pub fn into_inner(self) -> R {
+    self.result
+  }
+}
+
+pub struct MaskFutureAsSend<F> {
+  future: F,
+}
+
+impl<F> MaskFutureAsSend<F> {
+  /// Mark a non-`Send` future as `Send`. This is a trick to be able to use
+  /// `tokio::spawn()` (which requires `Send` futures) in a current thread
+  /// runtime.
+  ///
+  /// # Safety
+  ///
+  /// You must ensure that the future is actually used on the same
+  /// thread, ie. always use current thread runtime flavor from Tokio.
+  pub unsafe fn new(future: F) -> Self {
+    Self { future }
+  }
+}
+
+// SAFETY: we are cheating here - this struct is NOT really Send,
+// but we need to mark it Send so that we can use `spawn()` in Tokio.
+unsafe impl<F> Send for MaskFutureAsSend<F> {}
+
+impl<F: Future> Future for MaskFutureAsSend<F> {
+  type Output = MaskResultAsSend<F::Output>;
+
+  fn poll(
+    self: Pin<&mut Self>,
+    cx: &mut Context<'_>,
+  ) -> Poll<MaskResultAsSend<F::Output>> {
+    // SAFETY: We are sure that future is valid here
+    unsafe {
+      let me: &mut MaskFutureAsSend<F> = Pin::into_inner_unchecked(self);
+      let future = Pin::new_unchecked(&mut me.future);
+      match future.poll(cx) {
+        Poll::Pending => Poll::Pending,
+        Poll::Ready(result) => Poll::Ready(MaskResultAsSend { result }),
+      }
+    }
+  }
+}

core/task_queue.rs

@@ -127,7 +127,7 @@ mod tests {
     for i in 0..100 {
       let data = data.clone();
       tasks.push(task_queue.queue(async move {
-        tokio::task::spawn_blocking(move || {
+        crate::task::spawn_blocking(move || {
           let mut data = data.lock();
           if *data != i {
             panic!("Value was not equal.");

ext/cache/sqlite.rs

@@ -10,6 +10,7 @@ use std::time::UNIX_EPOCH;
 use async_trait::async_trait;
 use deno_core::error::AnyError;
 use deno_core::parking_lot::Mutex;
+use deno_core::task::spawn_blocking;
 use deno_core::AsyncRefCell;
 use deno_core::AsyncResult;
 use deno_core::ByteString;
@@ -99,7 +100,7 @@ impl Cache for SqliteBackedCache {
   async fn storage_open(&self, cache_name: String) -> Result<i64, AnyError> {
     let db = self.connection.clone();
     let cache_storage_dir = self.cache_storage_dir.clone();
-    tokio::task::spawn_blocking(move || {
+    spawn_blocking(move || {
       let db = db.lock();
       db.execute(
         "INSERT OR IGNORE INTO cache_storage (cache_name) VALUES (?1)",
@@ -124,7 +125,7 @@ impl Cache for SqliteBackedCache {
   /// Note: this doesn't check the disk, it only checks the sqlite db.
   async fn storage_has(&self, cache_name: String) -> Result<bool, AnyError> {
     let db = self.connection.clone();
-    tokio::task::spawn_blocking(move || {
+    spawn_blocking(move || {
       let db = db.lock();
       let cache_exists = db.query_row(
         "SELECT count(id) FROM cache_storage WHERE cache_name = ?1",
@@ -143,7 +144,7 @@ impl Cache for SqliteBackedCache {
   async fn storage_delete(&self, cache_name: String) -> Result<bool, AnyError> {
     let db = self.connection.clone();
     let cache_storage_dir = self.cache_storage_dir.clone();
-    tokio::task::spawn_blocking(move || {
+    spawn_blocking(move || {
       let db = db.lock();
       let maybe_cache_id = db
         .query_row(
@@ -210,7 +211,7 @@ impl Cache for SqliteBackedCache {
   > {
     let db = self.connection.clone();
     let cache_storage_dir = self.cache_storage_dir.clone();
-    let query_result = tokio::task::spawn_blocking(move || {
+    let query_result = spawn_blocking(move || {
       let db = db.lock();
       let result = db.query_row(
         "SELECT response_body_key, response_headers, response_status, response_status_text, request_headers
@@ -269,7 +270,7 @@ impl Cache for SqliteBackedCache {
     request: CacheDeleteRequest,
   ) -> Result<bool, AnyError> {
     let db = self.connection.clone();
-    tokio::task::spawn_blocking(move || {
+    spawn_blocking(move || {
       // TODO(@satyarohith): remove the response body from disk if one exists
       let db = db.lock();
       let rows_effected = db.execute(
@@ -287,7 +288,7 @@ async fn insert_cache_asset(
   put: CachePutRequest,
   response_body_key: Option<String>,
 ) -> Result<Option<String>, deno_core::anyhow::Error> {
-  tokio::task::spawn_blocking(move || {
+  spawn_blocking(move || {
     let maybe_response_body = {
       let db = db.lock();
       db.query_row(

ext/crypto/decrypt.rs

@@ -20,6 +20,7 @@ use deno_core::error::custom_error;
 use deno_core::error::type_error;
 use deno_core::error::AnyError;
 use deno_core::op;
+use deno_core::task::spawn_blocking;
 use deno_core::ZeroCopyBuf;
 use rsa::pkcs1::DecodeRsaPrivateKey;
 use rsa::PaddingScheme;
@@ -98,7 +99,7 @@ pub async fn op_crypto_decrypt(
       tag_length,
     } => decrypt_aes_gcm(key, length, tag_length, iv, additional_data, &data),
   };
-  let buf = tokio::task::spawn_blocking(fun).await.unwrap()?;
+  let buf = spawn_blocking(fun).await.unwrap()?;
   Ok(buf.into())
 }
 

ext/crypto/encrypt.rs

@@ -19,6 +19,7 @@ use ctr::Ctr64BE;
 use deno_core::error::type_error;
 use deno_core::error::AnyError;
 use deno_core::op;
+use deno_core::task::spawn_blocking;
 use deno_core::ZeroCopyBuf;
 use rand::rngs::OsRng;
 use rsa::pkcs1::DecodeRsaPublicKey;
@@ -99,7 +100,7 @@ pub async fn op_crypto_encrypt(
       key_length,
     } => encrypt_aes_ctr(key, key_length, &counter, ctr_length, &data),
   };
-  let buf = tokio::task::spawn_blocking(fun).await.unwrap()?;
+  let buf = spawn_blocking(fun).await.unwrap()?;
   Ok(buf.into())
 }
 

ext/crypto/generate_key.rs

@@ -2,6 +2,7 @@
 
 use deno_core::error::AnyError;
 use deno_core::op;
+use deno_core::task::spawn_blocking;
 use deno_core::ZeroCopyBuf;
 use elliptic_curve::rand_core::OsRng;
 use num_traits::FromPrimitive;
@@ -56,7 +57,7 @@ pub async fn op_crypto_generate_key(
       generate_key_hmac(hash, length)
     }
   };
-  let buf = tokio::task::spawn_blocking(fun).await.unwrap()?;
+  let buf = spawn_blocking(fun).await.unwrap()?;
   Ok(buf.into())
 }
 

ext/crypto/lib.rs

@@ -10,6 +10,7 @@ use deno_core::error::type_error;
 use deno_core::error::AnyError;
 use deno_core::op;
 
+use deno_core::task::spawn_blocking;
 use deno_core::OpState;
 use deno_core::ZeroCopyBuf;
 use serde::Deserialize;
@@ -601,7 +602,7 @@ pub async fn op_crypto_subtle_digest(
   algorithm: CryptoHash,
   data: ZeroCopyBuf,
 ) -> Result<ZeroCopyBuf, AnyError> {
-  let output = tokio::task::spawn_blocking(move || {
+  let output = spawn_blocking(move || {
     digest::digest(algorithm.into(), &data)
       .as_ref()
       .to_vec()

ext/ffi/call.rs

@@ -15,6 +15,7 @@ use deno_core::op;
 use deno_core::serde_json::Value;
 use deno_core::serde_v8;
 use deno_core::serde_v8::ExternalPointer;
+use deno_core::task::spawn_blocking;
 use deno_core::v8;
 use deno_core::OpState;
 use deno_core::ResourceId;
@@ -298,7 +299,7 @@ where
     .map(|v| v8::Local::<v8::TypedArray>::try_from(v.v8_value).unwrap());
   let out_buffer_ptr = out_buffer_as_ptr(scope, out_buffer);
 
-  let join_handle = tokio::task::spawn_blocking(move || {
+  let join_handle = spawn_blocking(move || {
     let PtrSymbol { cif, ptr } = symbol.clone();
     ffi_call(
       call_args,
@@ -345,7 +346,7 @@ pub fn op_ffi_call_nonblocking<'scope>(
     .map(|v| v8::Local::<v8::TypedArray>::try_from(v.v8_value).unwrap());
   let out_buffer_ptr = out_buffer_as_ptr(scope, out_buffer);
 
-  let join_handle = tokio::task::spawn_blocking(move || {
+  let join_handle = spawn_blocking(move || {
     let Symbol {
       cif,
       ptr,

ext/fs/std_fs.rs

@@ -9,6 +9,7 @@ use std::path::Path;
 use std::path::PathBuf;
 use std::rc::Rc;
 
+use deno_core::task::spawn_blocking;
 use deno_io::fs::File;
 use deno_io::fs::FsResult;
 use deno_io::fs::FsStat;
@@ -86,8 +87,7 @@ impl FileSystem for RealFs {
     options: OpenOptions,
   ) -> FsResult<Rc<dyn File>> {
     let opts = open_options(options);
-    let std_file =
+    let std_file = spawn_blocking(move || opts.open(path)).await??;
-      tokio::task::spawn_blocking(move || opts.open(path)).await??;
     Ok(Rc::new(StdFileResourceInner::file(std_file)))
   }
 
@@ -105,14 +105,14 @@ impl FileSystem for RealFs {
     recursive: bool,
     mode: u32,
   ) -> FsResult<()> {
-    tokio::task::spawn_blocking(move || mkdir(&path, recursive, mode)).await?
+    spawn_blocking(move || mkdir(&path, recursive, mode)).await?
   }
 
   fn chmod_sync(&self, path: &Path, mode: u32) -> FsResult<()> {
     chmod(path, mode)
   }
   async fn chmod_async(&self, path: PathBuf, mode: u32) -> FsResult<()> {
-    tokio::task::spawn_blocking(move || chmod(&path, mode)).await?
+    spawn_blocking(move || chmod(&path, mode)).await?
   }
 
   fn chown_sync(
@@ -129,53 +129,49 @@ impl FileSystem for RealFs {
     uid: Option<u32>,
     gid: Option<u32>,
   ) -> FsResult<()> {
-    tokio::task::spawn_blocking(move || chown(&path, uid, gid)).await?
+    spawn_blocking(move || chown(&path, uid, gid)).await?
   }
 
   fn remove_sync(&self, path: &Path, recursive: bool) -> FsResult<()> {
     remove(path, recursive)
   }
   async fn remove_async(&self, path: PathBuf, recursive: bool) -> FsResult<()> {
-    tokio::task::spawn_blocking(move || remove(&path, recursive)).await?
+    spawn_blocking(move || remove(&path, recursive)).await?
   }
 
   fn copy_file_sync(&self, from: &Path, to: &Path) -> FsResult<()> {
     copy_file(from, to)
   }
   async fn copy_file_async(&self, from: PathBuf, to: PathBuf) -> FsResult<()> {
-    tokio::task::spawn_blocking(move || copy_file(&from, &to)).await?
+    spawn_blocking(move || copy_file(&from, &to)).await?
   }
 
   fn stat_sync(&self, path: &Path) -> FsResult<FsStat> {
     stat(path).map(Into::into)
   }
   async fn stat_async(&self, path: PathBuf) -> FsResult<FsStat> {
-    tokio::task::spawn_blocking(move || stat(&path))
+    spawn_blocking(move || stat(&path)).await?.map(Into::into)
-      .await?
-      .map(Into::into)
   }
 
   fn lstat_sync(&self, path: &Path) -> FsResult<FsStat> {
     lstat(path).map(Into::into)
   }
   async fn lstat_async(&self, path: PathBuf) -> FsResult<FsStat> {
-    tokio::task::spawn_blocking(move || lstat(&path))
+    spawn_blocking(move || lstat(&path)).await?.map(Into::into)
-      .await?
-      .map(Into::into)
   }
 
   fn realpath_sync(&self, path: &Path) -> FsResult<PathBuf> {
     realpath(path)
   }
   async fn realpath_async(&self, path: PathBuf) -> FsResult<PathBuf> {
-    tokio::task::spawn_blocking(move || realpath(&path)).await?
+    spawn_blocking(move || realpath(&path)).await?
   }
 
   fn read_dir_sync(&self, path: &Path) -> FsResult<Vec<FsDirEntry>> {
     read_dir(path)
   }
   async fn read_dir_async(&self, path: PathBuf) -> FsResult<Vec<FsDirEntry>> {
-    tokio::task::spawn_blocking(move || read_dir(&path)).await?
+    spawn_blocking(move || read_dir(&path)).await?
   }
 
   fn rename_sync(&self, oldpath: &Path, newpath: &Path) -> FsResult<()> {
@@ -186,7 +182,7 @@ impl FileSystem for RealFs {
     oldpath: PathBuf,
     newpath: PathBuf,
   ) -> FsResult<()> {
-    tokio::task::spawn_blocking(move || fs::rename(oldpath, newpath))
+    spawn_blocking(move || fs::rename(oldpath, newpath))
       .await?
       .map_err(Into::into)
   }
@@ -199,7 +195,7 @@ impl FileSystem for RealFs {
     oldpath: PathBuf,
     newpath: PathBuf,
   ) -> FsResult<()> {
-    tokio::task::spawn_blocking(move || fs::hard_link(oldpath, newpath))
+    spawn_blocking(move || fs::hard_link(oldpath, newpath))
       .await?
       .map_err(Into::into)
   }
@@ -218,15 +214,14 @@ impl FileSystem for RealFs {
     newpath: PathBuf,
     file_type: Option<FsFileType>,
   ) -> FsResult<()> {
-    tokio::task::spawn_blocking(move || symlink(&oldpath, &newpath, file_type))
+    spawn_blocking(move || symlink(&oldpath, &newpath, file_type)).await?
-      .await?
   }
 
   fn read_link_sync(&self, path: &Path) -> FsResult<PathBuf> {
     fs::read_link(path).map_err(Into::into)
   }
   async fn read_link_async(&self, path: PathBuf) -> FsResult<PathBuf> {
-    tokio::task::spawn_blocking(move || fs::read_link(path))
+    spawn_blocking(move || fs::read_link(path))
       .await?
       .map_err(Into::into)
   }
@@ -235,7 +230,7 @@ impl FileSystem for RealFs {
     truncate(path, len)
   }
   async fn truncate_async(&self, path: PathBuf, len: u64) -> FsResult<()> {
-    tokio::task::spawn_blocking(move || truncate(&path, len)).await?
+    spawn_blocking(move || truncate(&path, len)).await?
   }
 
   fn utime_sync(
@@ -260,7 +255,7 @@ impl FileSystem for RealFs {
   ) -> FsResult<()> {
     let atime = filetime::FileTime::from_unix_time(atime_secs, atime_nanos);
     let mtime = filetime::FileTime::from_unix_time(mtime_secs, mtime_nanos);
-    tokio::task::spawn_blocking(move || {
+    spawn_blocking(move || {
       filetime::set_file_times(path, atime, mtime).map_err(Into::into)
     })
     .await?
@@ -289,7 +284,7 @@ impl FileSystem for RealFs {
     options: OpenOptions,
     data: Vec<u8>,
   ) -> FsResult<()> {
-    tokio::task::spawn_blocking(move || {
+    spawn_blocking(move || {
       let opts = open_options(options);
       let mut file = opts.open(path)?;
       #[cfg(unix)]
@@ -307,7 +302,7 @@ impl FileSystem for RealFs {
     fs::read(path).map_err(Into::into)
   }
   async fn read_file_async(&self, path: PathBuf) -> FsResult<Vec<u8>> {
-    tokio::task::spawn_blocking(move || fs::read(path))
+    spawn_blocking(move || fs::read(path))
       .await?
       .map_err(Into::into)
   }

ext/http/http_next.rs

@@ -17,6 +17,8 @@ use cache_control::CacheControl;
 use deno_core::error::AnyError;
 use deno_core::futures::TryFutureExt;
 use deno_core::op;
+use deno_core::task::spawn;
+use deno_core::task::JoinHandle;
 use deno_core::AsyncRefCell;
 use deno_core::AsyncResult;
 use deno_core::ByteString;
@@ -68,9 +70,6 @@ use std::rc::Rc;
 use tokio::io::AsyncReadExt;
 use tokio::io::AsyncWriteExt;
 
-use tokio::task::spawn_local;
-use tokio::task::JoinHandle;
-
 type Request = hyper1::Request<Incoming>;
 type Response = hyper1::Response<ResponseBytes>;
 
@@ -262,7 +261,7 @@ pub fn op_http_upgrade_raw(
   let (read_rx, write_tx) = tokio::io::split(read);
   let (mut write_rx, mut read_tx) = tokio::io::split(write);
 
-  spawn_local(async move {
+  spawn(async move {
     let mut upgrade_stream = WebSocketUpgrade::<ResponseBytes>::default();
 
     // Stage 2: Extract the Upgraded connection
@@ -285,7 +284,7 @@ pub fn op_http_upgrade_raw(
     // Stage 3: Pump the data
     let (mut upgraded_rx, mut upgraded_tx) = tokio::io::split(upgraded);
 
-    spawn_local(async move {
+    spawn(async move {
       let mut buf = [0; 1024];
       loop {
         let read = upgraded_rx.read(&mut buf).await?;
@@ -296,7 +295,7 @@ pub fn op_http_upgrade_raw(
       }
       Ok::<_, AnyError>(())
     });
-    spawn_local(async move {
+    spawn(async move {
       let mut buf = [0; 1024];
       loop {
         let read = write_rx.read(&mut buf).await?;
@@ -792,11 +791,10 @@ fn serve_https(
   cancel: Rc<CancelHandle>,
   tx: tokio::sync::mpsc::Sender<u32>,
 ) -> JoinHandle<Result<(), AnyError>> {
-  // TODO(mmastrac): This is faster if we can use tokio::spawn but then the send bounds get us
   let svc = service_fn(move |req: Request| {
     new_slab_future(req, request_info.clone(), tx.clone())
   });
-  spawn_local(
+  spawn(
     async {
       io.handshake().await?;
       // If the client specifically negotiates a protocol, we will use it. If not, we'll auto-detect
@@ -820,11 +818,10 @@ fn serve_http(
   cancel: Rc<CancelHandle>,
   tx: tokio::sync::mpsc::Sender<u32>,
 ) -> JoinHandle<Result<(), AnyError>> {
-  // TODO(mmastrac): This is faster if we can use tokio::spawn but then the send bounds get us
   let svc = service_fn(move |req: Request| {
     new_slab_future(req, request_info.clone(), tx.clone())
   });
-  spawn_local(serve_http2_autodetect(io, svc).try_or_cancel(cancel))
+  spawn(serve_http2_autodetect(io, svc).try_or_cancel(cancel))
 }
 
 fn serve_http_on<HTTP>(
@@ -916,7 +913,7 @@ where
   let cancel_clone = resource.cancel_handle();
 
   let listen_properties_clone: HttpListenProperties = listen_properties.clone();
-  let handle = spawn_local(async move {
+  let handle = spawn(async move {
     loop {
       let conn = listener
         .accept()

ext/http/lib.rs

@@ -20,6 +20,7 @@ use deno_core::futures::FutureExt;
 use deno_core::futures::StreamExt;
 use deno_core::futures::TryFutureExt;
 use deno_core::op;
+use deno_core::task::spawn;
 use deno_core::AsyncRefCell;
 use deno_core::AsyncResult;
 use deno_core::BufView;
@@ -68,7 +69,6 @@ use std::task::Poll;
 use tokio::io::AsyncRead;
 use tokio::io::AsyncWrite;
 use tokio::io::AsyncWriteExt;
-use tokio::task::spawn_local;
 
 use crate::network_buffered_stream::NetworkBufferedStream;
 use crate::reader_stream::ExternallyAbortableReaderStream;
@@ -184,7 +184,7 @@ impl HttpConnResource {
     };
     let (task_fut, closed_fut) = task_fut.remote_handle();
     let closed_fut = closed_fut.shared();
-    spawn_local(task_fut);
+    spawn(task_fut);
 
     Self {
       addr,
@@ -1005,7 +1005,7 @@ where
   Fut::Output: 'static,
 {
   fn execute(&self, fut: Fut) {
-    spawn_local(fut);
+    deno_core::task::spawn(fut);
   }
 }
 
@@ -1015,7 +1015,7 @@ where
   Fut::Output: 'static,
 {
   fn execute(&self, fut: Fut) {
-    spawn_local(fut);
+    deno_core::task::spawn(fut);
   }
 }
 

ext/io/lib.rs

@@ -2,6 +2,7 @@
 
 use deno_core::error::AnyError;
 use deno_core::op;
+use deno_core::task::spawn_blocking;
 use deno_core::AsyncMutFuture;
 use deno_core::AsyncRefCell;
 use deno_core::AsyncResult;
@@ -350,7 +351,7 @@ impl StdFileResourceInner {
         }
       }
     };
-    let (cell_value, result) = tokio::task::spawn_blocking(move || {
+    let (cell_value, result) = spawn_blocking(move || {
       let result = action(&mut cell_value);
       (cell_value, result)
     })
@@ -372,7 +373,7 @@ impl StdFileResourceInner {
     // we want to restrict this to one async action at a time
     let _permit = self.cell_async_task_queue.acquire().await;
 
-    tokio::task::spawn_blocking(action).await.unwrap()
+    spawn_blocking(action).await.unwrap()
   }
 }
 

ext/net/ops_tls.rs

@@ -26,6 +26,7 @@ use deno_core::futures::task::Waker;
 use deno_core::op;
 
 use deno_core::parking_lot::Mutex;
+use deno_core::task::spawn;
 use deno_core::AsyncRefCell;
 use deno_core::AsyncResult;
 use deno_core::ByteString;
@@ -74,7 +75,6 @@ use tokio::io::AsyncWriteExt;
 use tokio::io::ReadBuf;
 use tokio::net::TcpListener;
 use tokio::net::TcpStream;
-use tokio::task::spawn_local;
 
 #[derive(Copy, Clone, Debug, Eq, PartialEq)]
 enum Flow {
@@ -224,9 +224,9 @@ impl Drop for TlsStream {
     let use_linger_task = inner.poll_close(&mut cx).is_pending();
 
     if use_linger_task {
-      spawn_local(poll_fn(move |cx| inner.poll_close(cx)));
+      spawn(poll_fn(move |cx| inner.poll_close(cx)));
     } else if cfg!(debug_assertions) {
-      spawn_local(async {}); // Spawn dummy task to detect missing LocalSet.
+      spawn(async {}); // Spawn dummy task to detect missing runtime.
     }
   }
 }

ext/node/ops/crypto/mod.rs

@@ -4,6 +4,7 @@ use deno_core::error::type_error;
 use deno_core::error::AnyError;
 use deno_core::op;
 use deno_core::serde_v8;
+use deno_core::task::spawn_blocking;
 use deno_core::OpState;
 use deno_core::ResourceId;
 use deno_core::StringOrBuffer;
@@ -57,12 +58,7 @@ pub async fn op_node_check_prime_async(
   checks: usize,
 ) -> Result<bool, AnyError> {
   // TODO(@littledivy): use rayon for CPU-bound tasks
-  Ok(
+  Ok(spawn_blocking(move || primes::is_probably_prime(&num, checks)).await?)
-    tokio::task::spawn_blocking(move || {
-      primes::is_probably_prime(&num, checks)
-    })
-    .await?,
-  )
 }
 
 #[op]
@@ -74,9 +70,7 @@ pub fn op_node_check_prime_bytes_async(
   // TODO(@littledivy): use rayon for CPU-bound tasks
   Ok(async move {
     Ok(
-      tokio::task::spawn_blocking(move || {
+      spawn_blocking(move || primes::is_probably_prime(&candidate, checks))
-        primes::is_probably_prime(&candidate, checks)
-      })
         .await?,
     )
   })
@@ -462,7 +456,7 @@ pub async fn op_node_pbkdf2_async(
   digest: String,
   keylen: usize,
 ) -> Result<ZeroCopyBuf, AnyError> {
-  tokio::task::spawn_blocking(move || {
+  spawn_blocking(move || {
     let mut derived_key = vec![0; keylen];
     pbkdf2_sync(&password, &salt, iterations, &digest, &mut derived_key)
       .map(|_| derived_key.into())
@@ -477,7 +471,7 @@ pub fn op_node_generate_secret(buf: &mut [u8]) {
 
 #[op]
 pub async fn op_node_generate_secret_async(len: i32) -> ZeroCopyBuf {
-  tokio::task::spawn_blocking(move || {
+  spawn_blocking(move || {
     let mut buf = vec![0u8; len as usize];
     rand::thread_rng().fill(&mut buf[..]);
     buf.into()
@@ -535,7 +529,7 @@ pub async fn op_node_hkdf_async(
   info: ZeroCopyBuf,
   okm_len: usize,
 ) -> Result<ZeroCopyBuf, AnyError> {
-  tokio::task::spawn_blocking(move || {
+  spawn_blocking(move || {
     let mut okm = vec![0u8; okm_len];
     hkdf_sync(&hash, &ikm, &salt, &info, &mut okm)?;
     Ok(okm.into())
@@ -578,10 +572,7 @@ pub async fn op_node_generate_rsa_async(
   modulus_length: usize,
   public_exponent: usize,
 ) -> Result<(ZeroCopyBuf, ZeroCopyBuf), AnyError> {
-  tokio::task::spawn_blocking(move || {
+  spawn_blocking(move || generate_rsa(modulus_length, public_exponent)).await?
-    generate_rsa(modulus_length, public_exponent)
-  })
-  .await?
 }
 
 fn dsa_generate(
@@ -635,10 +626,7 @@ pub async fn op_node_dsa_generate_async(
   modulus_length: usize,
   divisor_length: usize,
 ) -> Result<(ZeroCopyBuf, ZeroCopyBuf), AnyError> {
-  tokio::task::spawn_blocking(move || {
+  spawn_blocking(move || dsa_generate(modulus_length, divisor_length)).await?
-    dsa_generate(modulus_length, divisor_length)
-  })
-  .await?
 }
 
 fn ec_generate(
@@ -677,7 +665,7 @@ pub fn op_node_ec_generate(
 pub async fn op_node_ec_generate_async(
   named_curve: String,
 ) -> Result<(ZeroCopyBuf, ZeroCopyBuf), AnyError> {
-  tokio::task::spawn_blocking(move || ec_generate(&named_curve)).await?
+  spawn_blocking(move || ec_generate(&named_curve)).await?
 }
 
 fn ed25519_generate() -> Result<(ZeroCopyBuf, ZeroCopyBuf), AnyError> {
@@ -704,7 +692,7 @@ pub fn op_node_ed25519_generate() -> Result<(ZeroCopyBuf, ZeroCopyBuf), AnyError
 #[op]
 pub async fn op_node_ed25519_generate_async(
 ) -> Result<(ZeroCopyBuf, ZeroCopyBuf), AnyError> {
-  tokio::task::spawn_blocking(ed25519_generate).await?
+  spawn_blocking(ed25519_generate).await?
 }
 
 fn x25519_generate() -> Result<(ZeroCopyBuf, ZeroCopyBuf), AnyError> {
@@ -739,7 +727,7 @@ pub fn op_node_x25519_generate() -> Result<(ZeroCopyBuf, ZeroCopyBuf), AnyError>
 #[op]
 pub async fn op_node_x25519_generate_async(
 ) -> Result<(ZeroCopyBuf, ZeroCopyBuf), AnyError> {
-  tokio::task::spawn_blocking(x25519_generate).await?
+  spawn_blocking(x25519_generate).await?
 }
 
 fn dh_generate_group(
@@ -772,7 +760,7 @@ pub fn op_node_dh_generate_group(
 pub async fn op_node_dh_generate_group_async(
   group_name: String,
 ) -> Result<(ZeroCopyBuf, ZeroCopyBuf), AnyError> {
-  tokio::task::spawn_blocking(move || dh_generate_group(&group_name)).await?
+  spawn_blocking(move || dh_generate_group(&group_name)).await?
 }
 
 fn dh_generate(
@@ -806,9 +794,7 @@ pub async fn op_node_dh_generate_async(
   prime_len: usize,
   generator: usize,
 ) -> Result<(ZeroCopyBuf, ZeroCopyBuf), AnyError> {
-  tokio::task::spawn_blocking(move || {
+  spawn_blocking(move || dh_generate(prime.as_deref(), prime_len, generator))
-    dh_generate(prime.as_deref(), prime_len, generator)
-  })
     .await?
 }
 
@@ -885,7 +871,7 @@ pub async fn op_node_scrypt_async(
   parallelization: u32,
   maxmem: u32,
 ) -> Result<ZeroCopyBuf, AnyError> {
-  tokio::task::spawn_blocking(move || {
+  spawn_blocking(move || {
     let mut output_buffer = vec![0u8; keylen as usize];
     let res = scrypt(
       password,
@@ -1081,5 +1067,5 @@ pub fn op_node_gen_prime(size: usize) -> ZeroCopyBuf {
 pub async fn op_node_gen_prime_async(
   size: usize,
 ) -> Result<ZeroCopyBuf, AnyError> {
-  Ok(tokio::task::spawn_blocking(move || gen_prime(size)).await?)
+  Ok(spawn_blocking(move || gen_prime(size)).await?)
 }

ext/websocket/lib.rs

@@ -591,6 +591,6 @@ where
   Fut::Output: 'static,
 {
   fn execute(&self, fut: Fut) {
-    tokio::task::spawn_local(fut);
+    deno_core::task::spawn(fut);
   }
 }

runtime/inspector_server.rs

@@ -15,6 +15,7 @@ use deno_core::futures::task::Poll;
 use deno_core::serde_json;
 use deno_core::serde_json::json;
 use deno_core::serde_json::Value;
+use deno_core::task::spawn;
 use deno_core::InspectorMsg;
 use deno_core::InspectorSessionProxy;
 use deno_core::JsRuntime;
@@ -109,7 +110,7 @@ where
   Fut::Output: 'static,
 {
   fn execute(&self, fut: Fut) {
-    tokio::task::spawn_local(fut);
+    deno_core::task::spawn(fut);
   }
 }
 
@@ -160,7 +161,7 @@ fn handle_ws_request(
 
   // spawn a task that will wait for websocket connection and then pump messages between
   // the socket and inspector proxy
-  tokio::task::spawn_local(async move {
+  spawn(async move {
     let websocket = if let Ok(w) = fut.await {
       w
     } else {

runtime/tokio_util.rs

@@ -1,5 +1,7 @@
 // Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
 
+use deno_core::task::MaskFutureAsSend;
+
 pub fn create_basic_runtime() -> tokio::runtime::Runtime {
   tokio::runtime::Builder::new_current_thread()
     .enable_io()
@@ -14,11 +16,14 @@ pub fn create_basic_runtime() -> tokio::runtime::Runtime {
     .unwrap()
 }
 
-pub fn run_local<F, R>(future: F) -> R
+pub fn create_and_run_current_thread<F, R>(future: F) -> R
 where
-  F: std::future::Future<Output = R>,
+  F: std::future::Future<Output = R> + 'static,
+  R: Send + 'static,
 {
   let rt = create_basic_runtime();
-  let local = tokio::task::LocalSet::new();
+  // SAFETY: this this is guaranteed to be running on a current-thread executor
-  local.block_on(&rt, future)
+  let future = unsafe { MaskFutureAsSend::new(future) };
+  let join_handle = rt.spawn(future);
+  rt.block_on(join_handle).unwrap().into_inner()
 }

runtime/web_worker.rs

@@ -3,7 +3,7 @@ use crate::colors;
 use crate::inspector_server::InspectorServer;
 use crate::ops;
 use crate::permissions::PermissionsContainer;
-use crate::tokio_util::run_local;
+use crate::tokio_util::create_and_run_current_thread;
 use crate::worker::FormatJsErrorFn;
 use crate::BootstrapOptions;
 use deno_broadcast_channel::InMemoryBroadcastChannel;
@@ -838,5 +838,5 @@ pub fn run_web_worker(
     debug!("Worker thread shuts down {}", &name);
     result
   };
-  run_local(fut)
+  create_and_run_current_thread(fut)
 }

tools/wpt/expectation.json

@@ -3729,7 +3729,9 @@
         ],
         "request-referrer.any.html": false,
         "request-referrer.any.worker.html": false,
-        "response-null-body.any.html": true
+        "response-null-body.any.html": {
+          "ignore": true
+        }
       },
       "response": {
         "json.any.html": true,