Ekhlass/Flutter_Documentation · Datasets at Hugging Face

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app. Frames that perform shader compilation are marked in dark
red:For more information on how to reduce shader compilation jank,
check out Reduce shader compilation jank on mobile.<topic_end>
<topic_start>
Frame analysis tab
Selecting a janky frame (slow, colored in red)
from the Flutter frames chart above shows debugging hints
in the Frame analysis tab. These hints help you diagnose
jank in your app, and notify you of any expensive operations
that we have detected that might have contributed to the slow frame time.<topic_end>
<topic_start>
Raster stats tab
info Note
For best results, this tool should be used with
the Impeller rendering engine. When using Skia,
the raster stats reported might be inconsistent
due to the timing of when shaders are compiled.If you have Flutter frames that are janking with
slow raster thread times, this tool might be able
to help you diagnose the source of the slow performance.
To generate raster stats:If you see an expensive layer, find the Dart code in your app
that is producing this layer and investigate further.
You can make changes to your code, hot reload,
and take new snapshots to see if the performance of a layer
was improved by your change.<topic_end>
<topic_start>
Timeline events tab
The timeline events chart shows all event tracing from your application.
The Flutter framework emits timeline events as it works to build frames,
draw scenes, and track other activity such as HTTP request timings
and garbage collection. These events show up here in the Timeline.
You can also send your own Timeline events using the dart:developer
Timeline and TimelineTask APIs.
For help with navigating and using the trace viewer,
click the ? button at the top right of the timeline
events tab bar. To refresh the timeline with new events from
your application, click the refresh button
(also in the upper right corner of the tab controls).<topic_end>
<topic_start>
Advanced debugging tools
<topic_end>
<topic_start>
Enhance tracing
To view more detailed tracing in the timeline events chart,
use the options in the enhance tracing dropdown:info Note
Frame times might be negatively affected when these options are enabled.To see the new timeline events, reproduce the activity
in your app that you are interested in tracing,
and then select a frame to inspect the timeline.<topic_end>
<topic_start>
Track widget builds
To see the build() method events in the timeline,
enable the Track Widget Builds option.
The name of the widget is shown in the timeline event.Watch this video for an example of tracking widget builds<topic_end>
<topic_start>
Track layouts
To see render object layout events in the timeline,
enable the Track Layouts option:Watch this video for an example of tracking layouts<topic_end>
<topic_start>
Track paints
To see render object paint events in the timeline,
enable the Track Paints option:Watch this video for an example of tracking paints<topic_end>
<topic_start>
More debugging options
To diagnose performance problems related to rendering layers,
toggle off a rendering layer.
These options are enabled by default.To see the effects on your app’s performance,
reproduce the activity in your app.
Then select the new frames in the frames chart
to inspect the timeline events
with the layers disabled.
If Raster time has significantly decreased,
excessive use of the effects you disabled might be contributing
to the jank you saw in your app.<topic_end>
<topic_start>
Import and export
DevTools supports importing and exporting performance snapshots.
Clicking the export button (upper-right corner above the
frame rendering chart) downloads a snapshot of the current data on the
performance page. To import a performance snapshot, you can drag and drop the
snapshot into DevTools from any page. Note that DevTools only
supports importing files that were originally exported from DevTools.<topic_end>
<topic_start>
Other resources
To learn how to monitor an app’s performance and
detect jank using DevTools, check out a guided
Performance View tutorial.
<topic_end>
<topic_start>Using the CPU profiler view
info Note
The CPU profiler view works with Dart CLI and mobile apps only.
Use Chrome DevTools to analyze performance
of a web app.The CPU profiler view allows you to record and profile a
session from your Dart or Flutter application.
The profiler can help you solve performance problems
or generally understand your app’s CPU activity.
The Dart VM collects CPU samples
(a snapshot of the CPU call stack at a single point in time)
and sends the data to DevTools for visualization.
By aggregating many CPU samples together,
the profiler can help you understand where the CPU
spends most of its time.info Note

app. Frames that perform shader compilation are marked in dark

red:For more information on how to reduce shader compilation jank,

check out Reduce shader compilation jank on mobile.<topic_end>

<topic_start>

Frame analysis tab

Selecting a janky frame (slow, colored in red)

from the Flutter frames chart above shows debugging hints

in the Frame analysis tab. These hints help you diagnose

jank in your app, and notify you of any expensive operations

that we have detected that might have contributed to the slow frame time.<topic_end>

<topic_start>

Raster stats tab

info Note

For best results, this tool should be used with

the Impeller rendering engine. When using Skia,

the raster stats reported might be inconsistent

due to the timing of when shaders are compiled.If you have Flutter frames that are janking with

slow raster thread times, this tool might be able

to help you diagnose the source of the slow performance.

To generate raster stats:If you see an expensive layer, find the Dart code in your app

that is producing this layer and investigate further.

You can make changes to your code, hot reload,

and take new snapshots to see if the performance of a layer

was improved by your change.<topic_end>

<topic_start>

Timeline events tab

The timeline events chart shows all event tracing from your application.

The Flutter framework emits timeline events as it works to build frames,

draw scenes, and track other activity such as HTTP request timings

and garbage collection. These events show up here in the Timeline.

You can also send your own Timeline events using the dart:developer

Timeline and TimelineTask APIs.

For help with navigating and using the trace viewer,

click the ? button at the top right of the timeline

events tab bar. To refresh the timeline with new events from

your application, click the refresh button

(also in the upper right corner of the tab controls).<topic_end>

<topic_start>

Advanced debugging tools

<topic_end>

<topic_start>

Enhance tracing

To view more detailed tracing in the timeline events chart,

use the options in the enhance tracing dropdown:info Note

Frame times might be negatively affected when these options are enabled.To see the new timeline events, reproduce the activity

in your app that you are interested in tracing,

and then select a frame to inspect the timeline.<topic_end>

<topic_start>

Track widget builds

To see the build() method events in the timeline,

enable the Track Widget Builds option.

The name of the widget is shown in the timeline event.Watch this video for an example of tracking widget builds<topic_end>

<topic_start>

Track layouts

To see render object layout events in the timeline,

enable the Track Layouts option:Watch this video for an example of tracking layouts<topic_end>

<topic_start>

Track paints

To see render object paint events in the timeline,

enable the Track Paints option:Watch this video for an example of tracking paints<topic_end>

<topic_start>

More debugging options

To diagnose performance problems related to rendering layers,

toggle off a rendering layer.

These options are enabled by default.To see the effects on your app’s performance,

reproduce the activity in your app.

Then select the new frames in the frames chart

to inspect the timeline events

with the layers disabled.

If Raster time has significantly decreased,

excessive use of the effects you disabled might be contributing

to the jank you saw in your app.<topic_end>

<topic_start>

Import and export

DevTools supports importing and exporting performance snapshots.

Clicking the export button (upper-right corner above the

frame rendering chart) downloads a snapshot of the current data on the

performance page. To import a performance snapshot, you can drag and drop the

snapshot into DevTools from any page. Note that DevTools only

supports importing files that were originally exported from DevTools.<topic_end>

<topic_start>

Other resources

To learn how to monitor an app’s performance and

detect jank using DevTools, check out a guided

Performance View tutorial.

<topic_end>

<topic_start>Using the CPU profiler view

info Note

The CPU profiler view works with Dart CLI and mobile apps only.

Use Chrome DevTools to analyze performance

of a web app.The CPU profiler view allows you to record and profile a

session from your Dart or Flutter application.

The profiler can help you solve performance problems

or generally understand your app’s CPU activity.

The Dart VM collects CPU samples

(a snapshot of the CPU call stack at a single point in time)

and sends the data to DevTools for visualization.

By aggregating many CPU samples together,

the profiler can help you understand where the CPU

spends most of its time.info Note