fix: let Node.js perform microtask checkpoint in the main process (#24131)

* fix: let Node.js perform microtask checkpoint in the main process

* fix: don't specify v8::MicrotasksScope for explicit policy

* fix: remove checkpoint from some call-sites

We already perform checkpoint at the end of a task,
either through MicrotaskRunner or through NodeBindings.
There isn't a need to add them again when calling into JS
except when dealing with promises.

* fix: remove checkpoint from some call-sites

We already perform checkpoint at the end of a task,
either through MicrotaskRunner or through NodeBindings.
There isn't a need to add them again when calling into JS
except when dealing with promises.

* fix incorrect specs

* default constructor arguments are considered for explicit mark

* add regression spec

shell/browser/api/electron_api_url_loader.cc

@@ -135,8 +135,6 @@ class JSChunkedDataPipeGetter : public gin::Wrappable<JSChunkedDataPipeGetter>,
     data_producer_ = std::make_unique<mojo::DataPipeProducer>(std::move(pipe));
 
     v8::HandleScope handle_scope(isolate_);
-    v8::MicrotasksScope script_scope(isolate_,
-                                     v8::MicrotasksScope::kRunMicrotasks);
     auto maybe_wrapper = GetWrapper(isolate_);
     v8::Local<v8::Value> wrapper;
     if (!maybe_wrapper.ToLocal(&wrapper)) {

shell/browser/electron_browser_main_parts.h

@@ -90,6 +90,7 @@ class ElectronBrowserMainParts : public content::BrowserMainParts {
 
   Browser* browser() { return browser_.get(); }
   BrowserProcessImpl* browser_process() { return fake_browser_process_.get(); }
+  NodeEnvironment* node_env() { return node_env_.get(); }
 
  protected:
   // content::BrowserMainParts:

shell/browser/javascript_environment.h

@@ -57,6 +57,8 @@ class NodeEnvironment {
   explicit NodeEnvironment(node::Environment* env);
   ~NodeEnvironment();
 
+  node::Environment* env() { return env_; }
+
  private:
   node::Environment* env_;
 

shell/browser/microtasks_runner.cc

@@ -4,6 +4,10 @@
 // found in the LICENSE file.
 
 #include "shell/browser/microtasks_runner.h"
+
+#include "shell/browser/electron_browser_main_parts.h"
+#include "shell/browser/javascript_environment.h"
+#include "shell/common/node_includes.h"
 #include "v8/include/v8.h"
 
 namespace electron {
@@ -15,7 +19,21 @@ void MicrotasksRunner::WillProcessTask(const base::PendingTask& pending_task,
 
 void MicrotasksRunner::DidProcessTask(const base::PendingTask& pending_task) {
   v8::Isolate::Scope scope(isolate_);
-  v8::MicrotasksScope::PerformCheckpoint(isolate_);
+  // In the browser process we follow Node.js microtask policy of kExplicit
+  // and let the MicrotaskRunner which is a task observer for chromium UI thread
+  // scheduler run the micotask checkpoint. This worked fine because Node.js
+  // also runs microtasks through its task queue, but after
+  // https://github.com/electron/electron/issues/20013 Node.js now performs its
+  // own microtask checkpoint and it may happen is some situations that there is
+  // contention for performing checkpoint between Node.js and chromium, ending
+  // up Node.js dealying its callbacks. To fix this, now we always lets Node.js
+  // handle the checkpoint in the browser process.
+  {
+    auto* node_env = electron::ElectronBrowserMainParts::Get()->node_env();
+    node::InternalCallbackScope microtasks_scope(
+        node_env->env(), v8::Local<v8::Object>(), {0, 0},
+        node::InternalCallbackScope::kAllowEmptyResource);
+  }
 }
 
 }  // namespace electron