One of my Manifest V3 addons is not waking up when it should

juraj.masiar · June 20, 2024, 4:37pm

This is gonna be one of those hard to reproduce issues, I can feel it.

I have a super simple addon that moves tabs received from other device into own window.

I’m using it almost every day and today it didn’t do its job, so I went to see about:debugging page, and I see it’s not running:

Even though it has listener for browser.tabs.onCreated, it won’t start even when I open new tab or window.

So, something is wrong. But what, and how can I help?
I hate reporting bugs that can’t be reproduced and there is like 100% chance this is one of those .
I’ve checked the browser console but I can’t find anything useful there.
Are there maybe some other logs I could check?

dotproto · June 21, 2024, 6:31pm

Is the extension consistently failing to start when a new tab opens in your browser right now? If not right now, at the time when you were observing it was it consistent? If so, we may be able to share some guidance about how to debug this issue using Firefox’s Browser Toolbox. Unfortunately, though, I don’t know enough about the implementation details of event dispatch to provide that guidance right now.

juraj.masiar · June 21, 2024, 7:28pm

I haven’t restarted browser yet so yes, I can still reproduce it now. I open new tab and the extension doesn’t wake up. And I can’t make it wake up even if I want to since it doesn’t have popup .

All other extensions work as expected.

UPDATE:
I think I’ve experienced similar issue not long ago with one of my other addons on my other PC at work. It started after I migrated it from persistent to not-persistent background script (but still MV2).

In that case, the addon had a browser.storage.sync.onChanged listener, which didn’t fired, even though the data in the store were changed. It happened only twice or so, so I didn’t investigated it further.

In any case, I’ve enabled and opened the Browser Toolbox and I can now inspect and debug everything, which is great, but indeed, without knowing where to put a debugger, it’s impossible to find the issue. Especially since there is no error in the console (after opening tabs) that would point me to the right direction…

dotproto · June 21, 2024, 7:46pm

I’m trying to see if I can get/find/figure out any guidance on debugging this. I’ll try to follow up in less than 30 min.

juraj.masiar · June 21, 2024, 7:55pm

If you can find someone skilled, I could even share a TeamViewer session and they could debug it on my machine.

dotproto · June 21, 2024, 8:16pm

To start, can you check the set of persistent listeners registered by your extensions? To do this, open Browser Toolbox and run the following snippet:

WebExtensionPolicy.getByID("admin@fastaddons.com_SendTabToDeviceEnhancer").extension.persistentListeners

Also, could you please share the following information?

Firefox version number
Firefox channel (stable, nightly, etc.)
OS & version number
Whether you’re using the published version of the add-on or a local version

juraj.masiar · June 21, 2024, 8:22pm

So, there are two listeners, as expected.
I’m running 128.b5, Developer Edition.
Using Windows 11 Pro 23H2.
The addon is normally installed from the store.

dotproto · June 21, 2024, 8:25pm

Thanks for that. I’m also seeing the same set of persistent listeners – I just installed the extension for testing/debugging purposes and ostensibly everything is working as expected right now.

juraj.masiar · June 21, 2024, 8:28pm

I was testing it at work too and it worked normally, as always.
But this is what I see now:
https://mega.nz/file/ZS50mLwa#MfvThAeoHtmwpS0t_yUkeSNVNVUqq840NiVg3unBieE

dotproto · June 21, 2024, 8:33pm

Very curious, indeed. Thanks for sharing a concrete video of the repro.

Could you run another snippet to get a more readable form of the listener data for us?

function convertNestedMap(m) { const res = {}; for (const [k, v] of m) { res[k] = typeof v?.has === "function" ? convertNestedMap(v) : v; } return res; }

JSON.stringify(convertNestedMap(WebExtensionPolicy.getByID("admin@fastaddons.com_SendTabToDeviceEnhancer").extension.persistentListeners), null, 2)

juraj.masiar · June 21, 2024, 8:34pm

'{
  "tabs": {
    "onCreated": {
      "[]": {
        "params": [],
        "nextPrimeId": 1,
        "listeners": [
          {
            "primeId": 0
          }
        ]
      }
    },
    "onUpdated": {
      "[null]": {
        "params": [
          null
        ],
        "nextPrimeId": 1,
        "listeners": [
          {
            "primeId": 0
          }
        ]
      }
    }
  }
}'

dotproto · June 21, 2024, 8:40pm

Interesting. That’s different than what I’m seeing locally when my extension is awake or asleep. I’ve passed this data on to the relevant engineers.

Sorry for the legginess of this process and thank you for the help so far!

juraj.masiar · June 21, 2024, 8:43pm

No problem , this is actually super exciting for me, even though it’s almost 11PM here . I plan to stay up at least one more hour.

I just hope it will help find the root cause. In the big picture, it will for sure help me too since I’ll receive less bug reports from my users .

dotproto · June 21, 2024, 8:51pm

The engineer I was working with so far had to leave, but it sounds like we got some useful data. I’m going to read through some relevant Firefox source and see if there’s any other data that might be useful to collect.

juraj.masiar · June 21, 2024, 8:55pm

OK, great.
I’ll try to keep my Firefox running over the weekend and even next week so feel free to write me if you need to run more experiments!

hans_squared · June 21, 2024, 8:58pm

Something unrelated that I noticed:
In background_sttd.js, the browser.windows.onFocusChanged listener gets registered inside the browser.tabs.onUpdated listener.
Doesn’t MV3 require that you register all listeners at the top level of the service worker?

juraj.masiar · June 21, 2024, 9:04pm

Only if you want the listener to be able to wake up the worker. Otherwise it will work only until the worker is alive, which is more-less enough for the specific use case it handles .

dotproto · June 21, 2024, 9:23pm

I’m going to keep poking around FF source for a bit longer, @juraj.masiar, but if you’re still up it’s probably best to call it a night. Thanks again for the help. I’ll be sure to follow up here as soon as I have an update over the next couple of days.

juraj.masiar · June 21, 2024, 9:26pm

OK, thanks for the help!
I’ll go sleep soon so good night and have a nice weekend .

dotproto · June 24, 2024, 8:45pm

Assuming the issue is still reproducing on your end, I have a pair of follow up questions for you, @juraj.masiar.

Could you run the following snippet in Browser Toolbox and share the result? It should be a short string.

WebExtensionPolicy.getByID("admin@fastaddons.com_SendTabToDeviceEnhancer").extension.backgroundState

Could you share the addonStartup.json.lz4 file from your profile directory with me? You can find the path to your profile directory by visiting about:profiles. I just sent you a message with my address.