Bug 59934 - binding inefficiencies spam debug console output and hurt debug performance
Summary: binding inefficiencies spam debug console output and hurt debug performance
Status: CONFIRMED
Alias: None
Product: Forms
Classification: Xamarin
Component: Android (show other bugs)
Version: 2.4.0
Hardware: PC Windows
: Normal normal
Target Milestone: ---
Assignee: Bugzilla
URL:
Depends on:
Blocks:
 
Reported: 2017-10-03 18:15 UTC by Frank Schwieterman
Modified: 2017-10-04 18:07 UTC (History)
4 users (show)

Tags: ac
Is this bug a regression?: ---
Last known good build:

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Status:
CONFIRMED

Description Frank Schwieterman 2017-10-03 18:15:51 UTC
Repro app is here: https://github.com/trainerroad/ListviewBugRepro/tree/noisey-binding   (be sure you are using the noisey-binding branch)

Select the x64 build of the droid project and deploy to an android phone.  Scroll the green/white list that comes up.  You will see a lot of spam in the debug output.  The expected result is you do not see the spam.  This is what the spam reads:

[0:] Binding: 'OddMessage' property not found on 'ListviewBugRepro.EvenListItemModel', target property: 'Xamarin.Forms.Label.Text'
[0:] Binding: 'OddMessage' property not found on 'ListviewBugRepro.EvenListItemModel', target property: 'Xamarin.Forms.Label.Text'
[0:] Binding: 'OddMessage' property not found on 'ListviewBugRepro.EvenListItemModel', target property: 'Xamarin.Forms.Label.Text'
[0:] Binding: 'OddMessage' property not found on 'ListviewBugRepro.EvenListItemModel', target property: 'Xamarin.Forms.Label.Text'
[0:] Binding: 'OddMessage' property not found on 'ListviewBugRepro.EvenListItemModel', target property: 'Xamarin.Forms.Label.Text'
[0:] Binding: 'OddMessage' property not found on 'ListviewBugRepro.EvenListItemModel', target property: 'Xamarin.Forms.Label.Text'
[0:] Binding: 'OddMessage' property not found on 'ListviewBugRepro.EvenListItemModel', target property: 'Xamarin.Forms.Label.Text'
[0:] Binding: 'OddMessage' property not found on 'ListviewBugRepro.EvenListItemModel', target property: 'Xamarin.Forms.Label.Text'
[0:] Binding: 'OddMessage' property not found on 'ListviewBugRepro.EvenListItemModel', target property: 'Xamarin.Forms.Label.Text'

There is no bug in the application causing the OddMessage to be looked for on the EvenListItemModel.  There is some bug in the Xamarin code causing this binding to be attempted.  The binding shouldn't be attempted and the error shouldn't be showing in the logs.  In our production app with more advanced models/views we get tons of these warning messages though nothing is broken.  It kills performance for debug builds.  We think there could be some performance waste on production builds as well, though performance in production is not obviously affected.

This bug does not occur on iOS.
Comment 2 Paul DiPietro [MSFT] 2017-10-04 18:07:41 UTC
Setting as confirmed until it can be investigated further.