Debug JavaScript with Safari stuck when press Continue or Step over

[loongliu]

Describe the bug
I tried to debug javascript with safari for iOS target and macOS target.
The Safari connected to the JSC successfully.
I can see the console, view the source code, put a breakpoint,
and the JSC stoped at the breakpoint.

But when I click Continue or Step over, the gui just stuck and nothing happened.
Tried debug for iOS target and macOS target, all the same situation.

To Reproduce
Steps to reproduce the behavior:

1. Build and run iOS target for default experience.js
2. Open safari and debug for the iOS target.
3. Put a breakpoint in babylon.max.js or experience.js.
4. the breakpoint worked, and the JSC stoped.
5. But Continue or Step over does not has any effect.

Expected behavior
Continue or Step over should work.

Screenshots

Other

• macOS 11.5.2
• XCode 13.0 (13A233)
• Safari 15.0 (16612.1.29.41.4, 16612)
• iOS 13.8

[darraghjburke]

Hi, thanks for the reporting this issue. I was able to repro it. I'll do some investigation and see if I can find a solution. Hopefully it's not a Safari bug :)

[darraghjburke]

I tested on another version of Safari but it was still broken. Do you happen to know if there's a version of Safari/MacOS/BabylonNative where this did work?

We think it may have worked at one point, but we're not sure.

[bghgary]

I investigated this a tiny bit. It looks like calling engine.runRenderLoop somehow interferes with the JSC debugger. Just commenting out this section makes the JSC debugger work fine.

    //engine.runRenderLoop(function () {
    //    scene.render();
    //});

I also tried just running the render loop with nothing in it, but this also breaks the JSC debugger.

    engine.runRenderLoop(function () {
    //    scene.render();
    });

[bghgary]

The reason why this doesn't work is because the main thread is blocked and can't receive messages from the debugger. We need to rework the way rendering work to fix this. See #1416. Closing as fixing the other issue should fix this.

[AJTech2002]

The reason why this doesn't work is because the main thread is blocked and can't receive messages from the debugger. We need to rework the way rendering work to fix this. See #946. Closing as fixing the other issue should fix this.

Hey @bghgary this makes sense, this is still an issue and makes debugging very difficult - you've linked back to the same thread, is there another issue that's tracking this and are there any temporary work arounds in the meantime?

Thanks :)

[bghgary]

Oops, I fixed the link. It should be #1416. Unfortunately, I don't know of a workaround. I know this is annoying. The fix is unfortunately a bigger change to how rendering works and will take some time before we can get to it.