fix(runtime): event loop panics in classic workers (#11756)

Classic worker scripts are now executed in the context of a Tokio
runtime. This does mean we can not spawn more tokio runtimes in
"op_worker_sync_fetch". We instead spawn a new thread there, that can
create a new Tokio runtime that we can use to block the worker thread.

cli/tests/integration/run_tests.rs

@@ -1109,6 +1109,13 @@ itest!(import_file_with_colon {
   output: "import_file_with_colon.ts.out",
   http_server: true,
 });
+
+itest!(classic_workers_event_loop {
+  args:
+    "run --enable-testing-features-do-not-use classic_workers_event_loop.js",
+  output: "classic_workers_event_loop.js.out",
+});
+
 // FIXME(bartlomieju): disabled, because this test is very flaky on CI
 // itest!(local_sources_not_cached_in_memory {
 //   args: "run --allow-read --allow-write no_mem_cache.js",

cli/tests/testdata/classic_workers_event_loop.js

@@ -0,0 +1,4 @@
+new Worker(
+  "data:application/javascript,setTimeout(() => {console.log('done'); self.close()}, 1000)",
+  { type: "classic" },
+);

cli/tests/testdata/classic_workers_event_loop.js.out

@@ -0,0 +1 @@
+done

runtime/ops/web_worker/sync_fetch.rs

@@ -38,29 +38,31 @@ pub fn op_worker_sync_fetch(
   let handle = state.borrow::<WebWorkerInternalHandle>().clone();
   assert_eq!(handle.worker_type, WebWorkerType::Classic);
 
-  // TODO(andreubotella) Make the runtime into a resource and add a new op to
-  // block on each request, so a script can run while the next loads.
+  // TODO(andreubotella) It's not good to throw an exception related to blob
+  // URLs when none of the script URLs use the blob scheme.
+  // Also, in which contexts are blob URLs not supported?
+  let blob_store = state
+    .try_borrow::<BlobStore>()
+    .ok_or_else(|| type_error("Blob URLs are not supported in this context."))?
+    .clone();
 
+  // TODO(andreubotella): make the below thread into a resource that can be
+  // re-used. This would allow parallel fecthing of multiple scripts.
+
+  let thread = std::thread::spawn(move || {
     let runtime = tokio::runtime::Builder::new_current_thread()
       .enable_io()
       .enable_time()
       .build()
       .unwrap();
 
-  // TODO(andreubotella) It's not good to throw an exception related to blob
-  // URLs when none of the script URLs use the blob scheme.
-  // Also, in which contexts are blob URLs not supported?
-  let blob_store = state.try_borrow::<BlobStore>().ok_or_else(|| {
-    type_error("Blob URLs are not supported in this context.")
-  })?;
-
     let handles: Vec<_> = scripts
       .into_iter()
       .map(|script| -> JoinHandle<Result<SyncFetchScript, AnyError>> {
         let blob_store = blob_store.clone();
         runtime.spawn(async move {
-        let script_url =
-          Url::parse(&script).map_err(|_| type_error("Invalid script URL"))?;
+          let script_url = Url::parse(&script)
+            .map_err(|_| type_error("Invalid script URL"))?;
 
           let (body, mime_type, res_url) = match script_url.scheme() {
             "http" | "https" => {
@@ -98,9 +100,10 @@ pub fn op_worker_sync_fetch(
               (Bytes::from(body), Some(mime_type), script)
             }
             "blob" => {
-            let blob = blob_store
-              .get_object_url(script_url)?
-              .ok_or_else(|| type_error("Blob for the given URL not found."))?;
+              let blob =
+                blob_store.get_object_url(script_url)?.ok_or_else(|| {
+                  type_error("Blob for the given URL not found.")
+                })?;
 
               let mime_type = mime_type_essence(&blob.media_type);
 
@@ -152,4 +155,7 @@ pub fn op_worker_sync_fetch(
       ret.push(script);
     }
     Ok(ret)
+  });
+
+  thread.join().unwrap()
 }

runtime/web_worker.rs

@@ -11,7 +11,6 @@ use deno_core::error::AnyError;
 use deno_core::error::JsError;
 use deno_core::futures::channel::mpsc;
 use deno_core::futures::future::poll_fn;
-use deno_core::futures::future::FutureExt;
 use deno_core::futures::stream::StreamExt;
 use deno_core::located_script_name;
 use deno_core::serde::Deserialize;
@@ -568,15 +567,14 @@ pub fn run_web_worker(
   // TODO(bartlomieju): run following block using "select!"
   // with terminate
 
+  let fut = async move {
     // Execute provided source code immediately
     let result = if let Some(source_code) = maybe_source_code {
       worker.execute_script(&located_script_name!(), &source_code)
     } else {
       // TODO(bartlomieju): add "type": "classic", ie. ability to load
       // script instead of module
-    let load_future = worker.execute_module(&specifier).boxed_local();
-
-    rt.block_on(load_future)
+      worker.execute_module(&specifier).await
     };
 
     let internal_handle = worker.internal_handle.clone();
@@ -597,7 +595,10 @@ pub fn run_web_worker(
       return Ok(());
     }
 
-  let result = rt.block_on(worker.run_event_loop(true));
+    let result = worker.run_event_loop(true).await;
     debug!("Worker thread shuts down {}", &name);
     result
+  };
+
+  rt.block_on(fut)
 }

tools/wpt/expectation.json

@@ -16744,13 +16744,7 @@
             "Cross-origin throw",
             "Redirect-to-cross-origin syntax error",
             "Redirect-to-Cross-origin throw"
-          ],
-          "report-error-cross-origin.sub.any.worker.html": false,
-          "report-error-redirect-to-cross-origin.sub.any.worker.html": false,
-          "report-error-same-origin.sub.any.worker.html": false,
-          "report-error-setTimeout-cross-origin.sub.any.worker.html": false,
-          "report-error-setTimeout-redirect-to-cross-origin.sub.any.worker.html": false,
-          "report-error-setTimeout-same-origin.sub.any.worker.html": false
+          ]
         }
       }
     },