Using the Firefox Profiler on Android just got a lot easier
Julien Wajsberg
Hey folks,
Yesterday Bug 1803607 [1] landed. What this brings is a new way to control the Firefox Profiler on Android, and a new way to capture MOZ_LOGs on Android.
All this in just one interface, that you may already know and use
on desktop.
Follow these simple steps:
- Open a tab, and go to about:logging.
- Select a suitable preset depending on your use case. This preset will define appropriate log modules as well as the right set of profiler options and captured threads for this use case.
- Start logging with the button at the top.
- Stop logging with the same button.
After stopping, you'll be given the choice to either save the profile to a local file, or upload the profile to the common storage.
If you pick the upload option, you'll be able to easily share the
link either with a messaging platform or with Firefox Sync if it's
configured. Note that opening the profiler URL on Fenix doesn't
work properly currently, but we're working on this!
You want to add a new logging preset for your use case? It's possible! Just add an item to the object in [2].
Would you want to add a profiler preset, you can do it as well in [3].
Feedback very welcome! Come and talk with us on the Firefox Profiler channel in Element :-)
Best,
--
Julien
[1] https://bugzilla.mozilla.org/show_bug.cgi?id=1803607
[3]
https://searchfox.org/mozilla-central/source/devtools/shared/performance-new/prefs-presets.sys.mjs
Nick Alexander
Hey folks,
Yesterday Bug 1803607 [1] landed. What this brings is a new way to control the Firefox Profiler on Android, and a new way to capture MOZ_LOGs on Android.
All this in just one interface, that you may already know and use on desktop.
Follow these simple steps:
- Open a tab, and go to about:logging.
- Select a suitable preset depending on your use case. This preset will define appropriate log modules as well as the right set of profiler options and captured threads for this use case.
- Start logging with the button at the top.
- Stop logging with the same button.
After stopping, you'll be given the choice to either save the profile to a local file, or upload the profile to the common storage.
Julien Wajsberg
Hey!
Here is a quick note that it's finally in the latest nightly in
the Android Play Store. Update your nightly to try it!
Cheers,
--
Julien
Julien Wajsberg
On Thu, Apr 10, 2025 at 3:16 AM 'Julien Wajsberg' via firef...@mozilla.org <firef...@mozilla.org> wrote:
Hey folks,
Yesterday Bug 1803607 [1] landed. What this brings is a new way to control the Firefox Profiler on Android, and a new way to capture MOZ_LOGs on Android.
All this in just one interface, that you may already know and use on desktop.
Follow these simple steps:
- Open a tab, and go to about:logging.
- Select a suitable preset depending on your use case. This preset will define appropriate log modules as well as the right set of profiler options and captured threads for this use case.
- Start logging with the button at the top.
- Stop logging with the same button.
After stopping, you'll be given the choice to either save the profile to a local file, or upload the profile to the common storage.
Julien and team -- this is great!
Thanks!
Can I ask 2 follow-up questions?
1. Can we connect `MOZ_LOG` and `adb logcat` together at some level so that we can use this mechanism to get logcat logs from users? This has historically been hard but could be a big win if possible.
I've been told that unfortunately it's not possible currently,
for android security reasons.
2. How does `about:logging` interact with startup profiling? That's a focus for the mobile and perf teams. Could we arrange for `about:logging` to be the/an entrypoint to startup profiling?
Interestingly I did something like that in
about:profiling very recently, but it's not exposed in
about:logging. This uses this
bit of code to restart the browser, but I don't know if the
same code would work on Android too. If somebody here knows,
please tell me!
Best,
--
Julien