src: flush V8 interrupts from Environment dtor

This avoids an edge-case memory leak.

Refs: #32523 (comment)

Author: addaleax

src/env.cc

@@ -42,11 +42,13 @@ using v8::NewStringType;
 using v8::Number;
 using v8::Object;
 using v8::Private;
+using v8::Script;
 using v8::SnapshotCreator;
 using v8::StackTrace;
 using v8::String;
 using v8::Symbol;
 using v8::TracingController;
+using v8::TryCatch;
 using v8::Undefined;
 using v8::Value;
 using worker::Worker;
@@ -394,9 +396,31 @@ Environment::Environment(IsolateData* isolate_data,
 }
 
 Environment::~Environment() {
-  if (Environment** interrupt_data = interrupt_data_.load())
+  if (Environment** interrupt_data = interrupt_data_.load()) {
+    // There are pending RequestInterrupt() callbacks. Tell them not to run,
+    // then force V8 to run interrupts by compiling and running an empty script
+    // so as not to leak memory.
     *interrupt_data = nullptr;
 
+    Isolate::AllowJavascriptExecutionScope allow_js_here(isolate());
+    HandleScope handle_scope(isolate());
+    TryCatch try_catch(isolate());
+    Context::Scope context_scope(context());
+
+#ifdef DEBUG
+    bool consistency_check = false;
+    isolate()->RequestInterrupt([](Isolate*, void* data) {
+      *static_cast<bool*>(data) = true;
+    }, &consistency_check);
+#endif
+
+    Local<Script> script;
+    if (Script::Compile(context(), String::Empty(isolate())).ToLocal(&script))
+      USE(script->Run(context()));
+
+    DCHECK(consistency_check);
+  }
+
   // FreeEnvironment() should have set this.
   CHECK(is_stopping());