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fix: enable interruption of V8 execution on Debugger.pause command #378

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fix: enable interruption of V8 execution on Debugger.pause command #378

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12 changes: 12 additions & 0 deletions NativeScript/inspector/JsV8InspectorClient.mm
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Original file line number Diff line number Diff line change
Expand Up @@ -128,6 +128,18 @@
dispatch_semaphore_signal(messageArrived_);
});

// Debugger.pause needs to interrupt V8 even if the main thread is busy
// executing JS. RequestInterrupt fires at the next safe bytecode boundary.
auto parsed = json::parse(message, nullptr, false);
if (!parsed.is_discarded() && parsed.contains("method") && parsed["method"] == "Debugger.pause") {
isolate_->RequestInterrupt(
[](Isolate* isolate, void* data) {
auto client = static_cast<JsV8InspectorClient*>(data);
client->session_->schedulePauseOnNextStatement({}, {});
},
this);
}
Comment on lines +131 to +141
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@coderabbitai coderabbitai Bot May 28, 2026

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⚠️ Potential issue | 🟡 Minor | ⚡ Quick win

Skip the interrupt path when the inspector is already paused.

runMessageLoopOnPause() already pumps frontend messages with runningNestedLoops_ = true. In that state no JS is executing, so this RequestInterrupt stays pending until after resume and can cause an unexpected immediate re-pause on the next statement. Gate the new branch on !runningNestedLoops_ and let the paused message loop handle Debugger.pause normally.

Suggested guard 
   auto parsed = json::parse(message, nullptr, false);
-  if (!parsed.is_discarded() && parsed.contains("method") && parsed["method"] == "Debugger.pause") {
+  bool shouldInterrupt = false;
+  dispatch_sync(this->messageLoopQueue_, ^{
+    shouldInterrupt = !runningNestedLoops_;
+  });
+  if (shouldInterrupt && !parsed.is_discarded() && parsed.contains("method") &&
+      parsed["method"] == "Debugger.pause") {
     isolate_->RequestInterrupt(
         [](Isolate* isolate, void* data) {
           auto client = static_cast<JsV8InspectorClient*>(data);
           client->session_->schedulePauseOnNextStatement({}, {});
         },
         this);
   }
🤖 Prompt for AI Agents 
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@NativeScript/inspector/JsV8InspectorClient.mm` around lines 131 - 141, The
RequestInterrupt path for "Debugger.pause" should be skipped when the inspector
is already in a paused nested loop; wrap the existing parsed-check and
isolate_->RequestInterrupt call in a guard that only runs when
runningNestedLoops_ is false (i.e., if (!runningNestedLoops_) { ... }), so that
runMessageLoopOnPause() (which sets runningNestedLoops_ = true) continues to
handle pause messages via session_->schedulePauseOnNextStatement rather than
queuing an interrupt that re-pauses immediately; update the branch in
JsV8InspectorClient around the RequestInterrupt lambda to check
runningNestedLoops_ before calling isolate_->RequestInterrupt.


tns::ExecuteOnMainThread([this, message]() {
dispatch_sync(this->messageLoopQueue_, ^{
// prevent execution if we're already pumping messages
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