xamarin/Xamarin.Forms

Webviews aren't being garbage collected when the containing page is popped

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#1,430 opened on Dec 20, 2017

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Description

Migrated from https://bugzilla.xamarin.com/show_bug.cgi?id=55749

Description

In the sample program, ThirdPage contains a webview defined in the xaml. Nothing is done to the webview in the code. Run the program and press the ThirdPage button, then the back arrow, 5 times and look at the memory allocations - there are 5 instances of the ThirdPage, WebView, WebViewRenderer, and WebClient (snapshot1 in the attached file). Not tap the button to garbage collect. The instances of ThirdPage and WebView drops to one, but WebViewRenderer and WebViewClient are still 5 (snapshot2). Why aren't these garbage collected?

Basic Information

  • Version with issue: 2.3.4

Reproduction Link

MemoryTest0.zip

Contributor guide

Tech stack
csharp
Domain
mobile
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-2 days
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
stale
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Basic C# knowledgeXamarin.Forms lifecycle
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
30
Research direction
Investigate WebViewRenderer and WebViewClient lifecycle in Xamarin.Forms. The issue mentions that WebViewRenderer and WebViewClient are not garbage collected when ThirdPage is popped. Look at the sample MemoryTest0.zip for reproduction steps. Check if there are any strong references from native side preventing GC. Consider the role of event handlers or object retention in renderers.