Improve Session Replay performance on iOS

[falk-stefan]

OS:

• Windows
• MacOS
• Linux (Ubuntu)

Platform:

• iOS
• Android

SDK:

• @sentry/react-native (>= 1.0.0)
• react-native-sentry (<= 0.43.2)

SDK version: 5.26.0

react-native version: 0.74.3

Are you using Expo?

• Yes
• No

Are you using sentry.io or on-premise?

• sentry.io (SaaS)
• on-premise

Configuration:

(@sentry/react-native)

Sentry.init({
  environment: environment.env,
  dsn: environment.sentry.dsn,
  sampleRate: environment.env === 'production' ? 0.05 : 1.0,
  tracePropagationTargets: [environment.apiUrl],
  _experiments: {
    // Currently under _experiments for 5.26.0-alpha releases
    replaysSessionSampleRate: 0.01,
    replaysOnErrorSampleRate: 1.0,
  },
  defaultIntegrations: [
    Sentry.mobileReplayIntegration({
      maskAllText: false,
      maskAllImages: false,
    }),
  ],
});

---

I have the following issue:

For testing, I have two phones available. One Galaxy A33 5G and an iPhone X.

After making my first iOS build I noticed that the application way really slow. Scrolling would sometimes completely getting stuck on the iOS device. However, I didn't have any issues on the Android device.

Long story short: After some thinking what the issue might be, I removed the Sentry.mobileReplayIntegration and noticed that the iPhone X was able to perform normally.

I am not sure if this is due to the device being comparatively old. However, the iPhone X isn't terribly weak. Not sure if this can be improved but I thought I'd just bring it up here just in case this isn't a known issue.

Expected result:

No significant performance impact.

[brustolin]

Hello @falk-stefan Thanks for reaching out.

We will investigate the impact on performance.
Were you testing this on debug alone, or did you try a release build?

I removed the Sentry.mobileReplayIntegration and noticed that the iPhone X was able to perform normally.

You mean, when the redact was enabled, there were no performance issues?

[falk-stefan]

Hi!

Were you testing this on debug alone, or did you try a release build?

I used an internal ad-hoc build on a physical iPhone X.

You mean, when the redact was enabled, there were no performance issues?

Essentially, I just commented out the entire section in order to remove the integration like so:

Sentry.init({
  environment: environment.env,
  dsn: environment.sentry.dsn,
  sampleRate: environment.env === 'production' ? 0.05 : 1.0,
  tracePropagationTargets: [environment.apiUrl],
  // _experiments: {
  //   // Currently under _experiments for 5.26.0-alpha releases
  //   replaysSessionSampleRate: 0.01,
  //   replaysOnErrorSampleRate: 1.0,
  // },
  // defaultIntegrations: [
  //   Sentry.mobileReplayIntegration({
  //     maskAllText: false,
  //     maskAllImages: false,
  //   }),
  // ],
});

After installing a new ad-hoc build on the device, the performance was back to normal.

[brustolin]

Essentially, I just commented out the entire section in order to remove the integration like so

Ok, so you disabled session replay completely.
Thanks for the answers!

[krystofwoldrich]

From the older Apple devices we have iP 6 and 8 (the same chip as X) available, have we tested any of the recent SDK builds on them?

[yefim]

We've narrowed it down to @sentry/integrations version 7.114.0. We're running @sentry/react-native 5.26.0. I posted video and workaround at #3963 (comment)

[krystofwoldrich]

@yefim Thank you for the message and the video, just to confirm, your app was slow when using the captureConsoleIntegration and when removing it, it worked correctly?

Were you also using the Mobile Replay feature?

[yefim]

@krystofwoldrich yes, it was the captureConsoleIntegration causing the slowness. I had not enabled the Mobile Replay feature. I filed #3992

[krystofwoldrich]

@1forh Thank you.

[krystofwoldrich]

We have tested Session Replay recording with iPhone 8 and iPhone 14 Pro and we can confirm the impact on the lower end devices is larger. We recommend enabling SR only on high end iOS devices.

[LMakshow]

Updated Sentry SDK to 6.4.0 to check the issue again on iPhone 14 Pro. There's still a noticeable scroll stutter which would annoy me as a user. It's not as noticeable as on iPad 7th gen, but I won't recommend pushing it to production to my team.
Also, Xcode shows a warning on this code line alerting about potential priority inversions. Could it help with troubleshooting the issue?

[krystofwoldrich]

@brustolin Do you also get the Xcode warning?

[LMakshow]

To get this warning, you need to build and run the app from Xcode, not from react-native/expo CLI (so Xcode will attach its own debugger).

[brustolin]

@brustolin Do you also get the Xcode warning?

This is supposed to be fixed. I will take a look.

[bruno-garcia]

@LMakshow is the warning still happening? Sorry but Brustolin is no longer at Sentry

[LMakshow]

@bruno-garcia
We still had the issue of 1/second stutters while testing the iOS replays on the Sentry 6.5.0 version. I didn't check the XCode warnings then. Let me try it a bit later. I might also try to reproduce the issue with the sample app if that might help.

[kahest]

Closing this as duplicate of getsentry/sentry-cocoa#4000. Please add relevant information to the other issue as needed and track the progress there