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The App performance dashboard

How the app starts, how its frames build and raster, which screens are slow or busy, and where people are frustrated.

Who it is for: The engineers tuning how the app feels: startup, frames, slow screens and frustrated taps.

Open it from Dashboards in the Observatory: choose App performance. It is a built-in board, so it is read-only; Save a copy makes one you can change. How every panel reads the range, its colors and its empty states is on Reading a board.

The toolbar: the filters Build, Platform, Service and Screen, each All until you pick a value, and the time range. Each menu lists the values flutter.frame.build carries in the range. Each panel below names the filters that narrow it.

[TODO: screenshot of the App performance dashboard over the last 24 hours, every filter All: Overview, Frames and Screens]

Overview

Cold start (p75)

Cold start time at the 75th percentile. Keep it under 3 s; Google Play flags cold starts of 5 s or more.

  • How it is computed: The 75th percentile of flutter.app.startup.duration for cold starts (app.start.type cold). One figure for the whole picked range.
  • Better: Lower is better.
  • Colors: The figure turns amber above 3 s and red above 5 s.
  • Filters: Build, Platform and Service narrow it; Screen does not.
  • Opens: its title opens the Metric screen on flutter.app.startup.duration.

Frame build (p95)

The UI thread's share of a frame: build, layout and paint recording, at the 95th percentile. The 60 Hz budget is 16.7 ms; a frame past 33 ms takes two.

  • How it is computed: The 95th percentile of flutter.frame.build. One figure for the whole picked range.
  • Better: Lower is better.
  • Colors: The figure turns amber above 16 ms and red above 33 ms.
  • Filters: Build, Platform, Service and Screen narrow it.
  • Opens: its title opens the Metric screen on flutter.frame.build.

Janky frames

Dropped frames, of all frames built. Keep it under 5%; at 10% the app feels broken.

  • How it is computed: flutter.frame.dropped divided by the number of flutter.frame.build samples, as a percent. One figure for the whole picked range.
  • Better: Lower is better.
  • Colors: The figure turns amber above 5% and red above 10%.
  • Filters: Build, Platform, Service and Screen narrow it.
  • Opens: its title opens the Metric screen on flutter.frame.dropped.

Severe and frozen frames

Frames well past the vsync budget, of all frames built.

  • How it is computed: flutter.frame.dropped where flutter.frame.severity is severe or frozen, divided by the number of flutter.frame.build samples, as a percent. One figure for the whole picked range.
  • Better: Lower is better.
  • Colors: The figure turns amber above 1% and red above 3%.
  • Filters: Build, Platform, Service and Screen narrow it.
  • Opens: its title opens the Metric screen on flutter.frame.dropped.

UI hangs

A UI hang is a UI-thread hang the watchdog reported. Info is noticeable, mild is one the user feels, severe is long enough that the OS may offer to close the app.

  • How it is computed: flutter.anr.events, every severity. One figure for the whole picked range.
  • Better: Lower is better. Beside the figure, its change from the prior range of the same length: green when it moved the better way, red when it moved the other way.
  • Filters: Build, Platform and Service narrow it; Screen does not.
  • Opens: its title opens the Metric screen on flutter.anr.events.

Memory usage

The app process's resident memory, averaged across devices. Healthy under 200 MB; OOM-kill risk grows past 400 MB.

  • How it is computed: The average of process.memory.usage from Flutter app processes (those that carry flutter.build.mode); a server process never counts here. One figure for the whole picked range.
  • Better: Lower is better.
  • Colors: The figure turns amber above 200 MB and red above 400 MB.
  • Filters: Build, Platform and Service narrow it; Screen does not.
  • Opens: its title opens the Metric screen on process.memory.usage.

Frames

Frame build (p95) over time

Frame build time at the 95th percentile, each step.

  • How it is computed: The 95th percentile of flutter.frame.build. Lines, one point per step across the picked range.
  • Filters: Build, Platform, Service and Screen narrow it.
  • Opens: its title opens the Metric screen on flutter.frame.build.

Frame raster (p95) over time

The raster thread's share of a frame at the 95th percentile, each step.

  • How it is computed: The 95th percentile of flutter.frame.raster. Lines, one point per step across the picked range.
  • Filters: Build, Platform, Service and Screen narrow it.
  • Opens: its title opens the Metric screen on flutter.frame.raster.

Dropped frames per minute by screen

The six screens dropping most, each step.

  • How it is computed: The per-minute rate of flutter.frame.dropped, one line per screen (app.screen.name). Lines, one point per step across the picked range.
  • Filters: Build, Platform, Service and Screen narrow it.
  • Opens: its title opens the Metric screen on flutter.frame.dropped.

Dropped frames by severity

Mild, severe or frozen: by how much the frame missed its budget.

  • How it is computed: flutter.frame.dropped, counted per flutter.frame.severity. A ranked list, each figure for the whole picked range.
  • Filters: Build, Platform, Service and Screen narrow it.
  • Opens: its title opens the Metric screen on flutter.frame.dropped.

Frames missing their vsync deadline

Frames that missed their vsync deadline: each device's latest count, summed.

  • How it is computed: flutter.vsync.deadline_miss_count, summed across devices. One figure for the whole picked range.
  • Better: Lower is better.
  • Filters: Build, Platform and Service narrow it; Screen does not.
  • Opens: its title opens the Metric screen on flutter.vsync.deadline_miss_count.

Screens

How long a route stayed up, from its push to the pop or replace that ended it. A route never popped (often the first screen) is not in it.

  • How it is computed: The 95th percentile of flutter.navigation.duration per screen (app.screen.name), the top ten. A ranked list, each figure for the whole picked range.
  • Filters: Build, Platform, Service and Screen narrow it.
  • Opens: its title opens the Metric screen on flutter.navigation.duration.

Most visited screens

Screen views in this range, one each time a screen became current.

  • How it is computed: Log records with event.name dartastic.screen.view, counted per screen (the record's app.screen.name), the top ten. A ranked list, each figure for the whole picked range.
  • Filters: Build, Platform, Service and Screen narrow it.
  • Opens: its title opens Logs.

Tap to next screen by screen (p75)

From a tap to the screen it opened becoming current.

  • How it is computed: The 75th percentile of dartastic.screen.interaction_to_next_view per screen, the top ten. A ranked list, each figure for the whole picked range.
  • Filters: Build, Platform, Service and Screen narrow it.
  • Opens: its title opens the Metric screen on dartastic.screen.interaction_to_next_view.

Network settled by screen (p75)

From a screen's start to its last request finishing.

  • How it is computed: The 75th percentile of dartastic.screen.network_settled per screen, the top ten. A ranked list, each figure for the whole picked range.
  • Filters: Build, Platform, Service and Screen narrow it.
  • Opens: its title opens the Metric screen on dartastic.screen.network_settled.

Startup

Starts by type

Cold, warm and hot starts in this range.

  • How it is computed: The number of flutter.app.startup.duration samples per app.start.type (cold, warm, hot). A ranked list, each figure for the whole picked range.
  • Filters: Build, Platform and Service narrow it; Screen does not.
  • Opens: its title opens the Metric screen on flutter.app.startup.duration.

Cold start (p95) over time

Cold start time at the 95th percentile, each step.

  • How it is computed: The 95th percentile of flutter.app.startup.duration for cold starts. Lines, one point per step across the picked range.
  • Filters: Build, Platform and Service narrow it; Screen does not.
  • Opens: its title opens the Metric screen on flutter.app.startup.duration.

Warm and hot starts (p95) over time

Warm and hot start time at the 95th percentile, each step.

  • How it is computed: The 95th percentile of flutter.app.startup.duration for warm and hot starts together. Lines, one point per step across the picked range.
  • Filters: Build, Platform and Service narrow it; Screen does not.
  • Opens: its title opens the Metric screen on flutter.app.startup.duration.

Interaction

User actions

Taps the app accepted.

  • How it is computed: dartastic.action.count. One figure for the whole picked range.
  • Better: Higher is better. Beside the figure, its change from the prior range of the same length: green when it moved the better way, red when it moved the other way.
  • Filters: Build, Platform, Service and Screen narrow it.
  • Opens: its title opens the Metric screen on dartastic.action.count.

Frustration signals

Rage taps (three or more on one target within a second), dead taps (nothing happened within 3 s) and error taps (an error during the tap or within 100 ms of it).

  • How it is computed: dartastic.frustration.signal.count. One figure for the whole picked range.
  • Better: Lower is better. Beside the figure, its change from the prior range of the same length: green when it moved the better way, red when it moved the other way.
  • Colors: The figure turns amber above 25 and red above 100.
  • Filters: Build, Platform, Service and Screen narrow it.
  • Opens: its title opens the Metric screen on dartastic.frustration.signal.count.

Frustration by type

Frustration signals by type.

  • How it is computed: dartastic.frustration.signal.count, counted per dartastic.frustration.signal.type. A ranked list, each figure for the whole picked range.
  • Filters: Build, Platform, Service and Screen narrow it.
  • Opens: its title opens the Metric screen on dartastic.frustration.signal.count.

Frustration by screen

The screens with the most frustration signals.

  • How it is computed: dartastic.frustration.signal.count, counted per screen (app.screen.name), the top ten. A ranked list, each figure for the whole picked range.
  • Filters: Build, Platform, Service and Screen narrow it.
  • Opens: its title opens the Metric screen on dartastic.frustration.signal.count.

Actions by screen

The screens where people tap most.

  • How it is computed: dartastic.action.count, counted per screen, the top ten. A ranked list, each figure for the whole picked range.
  • Filters: Build, Platform, Service and Screen narrow it.
  • Opens: its title opens the Metric screen on dartastic.action.count.