perf(core): do not drive JsInspector by default (#16410)

Part of https://github.com/denoland/deno/pull/16377

core/ops_builtin_v8.rs

@@ -766,6 +766,10 @@ fn op_dispatch_exception(
     .dispatched_exceptions
     .push_front(v8::Global::new(scope, exception.v8_value));
   // Only terminate execution if there are no inspector sessions.
+  if state.inspector.is_none() {
+    scope.terminate_execution();
+    return;
+  }
   match state.inspector().try_borrow() {
     Ok(inspector) if !inspector.has_active_sessions() => {
       scope.terminate_execution();

core/runtime.rs

@@ -180,7 +180,7 @@ pub struct JsRuntimeState {
   // TODO(nayeemrmn): This is polled in `exception_to_err_result()` which is
   // flimsy. Try to poll it similarly to `pending_promise_exceptions`.
   pub(crate) dispatched_exceptions: VecDeque<v8::Global<v8::Value>>,
-  inspector: Option<Rc<RefCell<JsRuntimeInspector>>>,
+  pub(crate) inspector: Option<Rc<RefCell<JsRuntimeInspector>>>,
   waker: AtomicWaker,
 }
 
@@ -275,6 +275,7 @@ pub struct RuntimeOptions {
   /// [CompiledWasmModuleStore]. If no [CompiledWasmModuleStore] is specified,
   /// `WebAssembly.Module` objects cannot be serialized.
   pub compiled_wasm_module_store: Option<CompiledWasmModuleStore>,
+  pub inspector: bool,
 }
 
 impl Drop for JsRuntime {
@@ -429,8 +430,14 @@ impl JsRuntime {
     };
 
     op_state.borrow_mut().put(isolate_ptr);
-    let inspector =
+    let inspector = if options.inspector {
-      JsRuntimeInspector::new(&mut isolate, global_context.clone());
+      Some(JsRuntimeInspector::new(
+        &mut isolate,
+        global_context.clone(),
+      ))
+    } else {
+      None
+    };
 
     let loader = options
       .module_loader
@@ -439,7 +446,7 @@ impl JsRuntime {
       let mut state = state_rc.borrow_mut();
       state.global_realm = Some(JsRealm(global_context));
       state.op_ctxs = op_ctxs;
-      state.inspector = Some(inspector);
+      state.inspector = inspector;
     }
     isolate.set_data(
       Self::STATE_DATA_OFFSET,
@@ -901,6 +908,18 @@ impl JsRuntime {
     }
   }
 
+  pub fn maybe_init_inspector(&mut self) {
+    if self.state.borrow().inspector.is_some() {
+      return;
+    }
+
+    let mut state = self.state.borrow_mut();
+    state.inspector = Some(JsRuntimeInspector::new(
+      self.v8_isolate.as_mut().unwrap(),
+      state.global_realm.clone().unwrap().0,
+    ));
+  }
+
   pub fn poll_value(
     &mut self,
     global: &v8::Global<v8::Value>,
@@ -970,13 +989,19 @@ impl JsRuntime {
     cx: &mut Context,
     wait_for_inspector: bool,
   ) -> Poll<Result<(), Error>> {
-    // We always poll the inspector first
+    let has_inspector: bool;
-    let _ = self.inspector().borrow_mut().poll_unpin(cx);
+
     {
       let state = self.state.borrow();
+      has_inspector = state.inspector.is_some();
       state.waker.register(cx.waker());
     }
 
+    if has_inspector {
+      // We poll the inspector first.
+      let _ = self.inspector().borrow_mut().poll_unpin(cx);
+    }
+
     self.pump_v8_message_loop()?;
 
     // Ops
@@ -1030,10 +1055,12 @@ impl JsRuntime {
 
     let pending_state = self.event_loop_pending_state();
     if !pending_state.is_pending() && !maybe_scheduling {
-      let inspector_has_active_sessions =
+      if has_inspector {
-        self.inspector().borrow_mut().has_active_sessions();
+        let inspector_has_active_sessions =
-      if wait_for_inspector && inspector_has_active_sessions {
+          self.inspector().borrow_mut().has_active_sessions();
-        return Poll::Pending;
+        if wait_for_inspector && inspector_has_active_sessions {
+          return Poll::Pending;
+        }
       }
 
       return Poll::Ready(Ok(()));

runtime/web_worker.rs

@@ -457,6 +457,7 @@ impl WebWorker {
       shared_array_buffer_store: options.shared_array_buffer_store.clone(),
       compiled_wasm_module_store: options.compiled_wasm_module_store.clone(),
       extensions,
+      inspector: options.maybe_inspector_server.is_some(),
       ..Default::default()
     });
 

runtime/worker.rs

@@ -248,6 +248,7 @@ impl MainWorker {
       shared_array_buffer_store: options.shared_array_buffer_store.clone(),
       compiled_wasm_module_store: options.compiled_wasm_module_store.clone(),
       extensions,
+      inspector: options.maybe_inspector_server.is_some(),
       ..Default::default()
     });
 
@@ -441,6 +442,7 @@ impl MainWorker {
   /// Create new inspector session. This function panics if Worker
   /// was not configured to create inspector.
   pub async fn create_inspector_session(&mut self) -> LocalInspectorSession {
+    self.js_runtime.maybe_init_inspector();
     self.js_runtime.inspector().borrow().create_local_session()
   }