text stringlengths 1 474 |
|---|
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 |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.