We use the EO WebBrowser in our WPF application. As our users navigate around our application, the EO browser is created and disposed when no longer needed. This creation and dispose could happen thousands of times in an applicarion process lifetime as our applications run by operators and they are required to run the application without restarting for months.

We have created a simple WPF application to reproduce this issue. We will upload the source code for this. Click on the Create button on the top middle area to create an instance of EO Web Browser. Click Dispose button to dispose the EO Web Browser instance. You can also check the Auto check box to automatically create and dispose repeatedly. Watch the User Objects count in the Task Manager. The count keeps growing as new instances are created and disposed.

Note that there is limit of 10,000 user objects per application and the application will crash when it reaches this limit.

We notice the same issue can be reproduced in the sample TabbedBrowser application. Just create new tabs to show web page and close tabs. As more tabs created and closed the user objects count keeps growing.

Our release is on hold due to this issue. This is kind of extremely urgent for us. Appreciate your help.

EO version used: 2018.0.28

Thank you for looking into this. The user object leak in the main process. And this is our concern. We are seeing the user object leak every time consistently on the main process (the test application). There must be something different in your setup. We can reproduce in all our machines.

When we run Deleaker utility we do see indication that there is leak inside Eo WebControl.

By the we use Window 10 64 bit OS.

As I stated in the title and in the initial post above, the leak we are reporting is the "User Objects" NOT "Handles". It is the "User Objects" that are leaking. In the Task manager, details tab select the "User Objects" column and see the leak when running the sample application.

Here are some leads based on analysis from our team members:

1.Possible window leak in EO
Looks like there is window leak every time we create and dispose EO WebControl instance. Following is the analysis from running Spyxx tool.

We can continuously reproduce two user objects leak once we create and dispose the web control. We used Spyxx to observe the window and found there are window handles leak which came from EO. The below windows are created after we open and close the browser:

The highlighted windows were created by multiple times of open/close window which contains webbrowser and are not released. It’s about one window created per action (open/close WebBrowser)

Window 000B0A38 "SystemResourceNotifyWindow" HwndWrapper[view.exe;;623c14db-f338-4dae-957f-065ba17e74cf]
Window 00150CC2 "" eo.nativewnd.v18.0.28.0.0.26482361
Window 00270DBC "" eo.nativewnd.v18.0.28.0.0.26482361
Window 002F09DC "" eo.nativewnd.v18.0.28.0.0.26482361
Window 00090B6A "" eo.nativewnd.v18.0.28.0.0.26482361
Window 00B20822 "" eo.nativewnd.v18.0.28.0.0.26482361
Window 00150A08 "" eo.nativewnd.v18.0.28.0.0.26482361
Window 00040B86 "" eo.nativewnd.v18.0.28.0.0.26482361
Window 001A0410 "" eo.nativewnd.v18.0.28.0.0.26482361
Window 002A0D2C "" eo.nativewnd.v18.0.28.0.0.26482361
Window 00390B1E "" eo.nativewnd.v18.0.28.0.0.26482361
Window 00050B78 "" eo.nativewnd.v18.0.28.0.0.26482361
Window 00050C3E "" eo.nativewnd.v18.0.28.0.0.26482361
Window 000D082E "" eo.nativewnd.v18.0.28.0.0.26482361
Window 00040C66 "" eo.nativewnd.v18.0.28.0.0.26482361
Window 00040C62 "" eo.nativewnd.v18.0.28.0.0.26482361
Window 005804AC "" eo.nativewnd.v18.0.28.0.0.26482361
Window 02C40BB0 "" eo.nativewnd.v18.0.28.0.0.26482361
Window 000D0A88 "" eo.nativewnd.v18.0.28.0.0.26482361

2. Another common problem in .Net code that may lead this kind of leak is not properly unregistering .Net event subscriptions. Please ensure all the events registered are unsubscribed properly. For every += in the code must have corresponding -= to unsubscribe.
For example: engine.Stopped += Engine_Stopped; should have corresponding unregister call engine.Stopped -= Engine_Stopped;

Great, thank you. When can we have a build with this fix?

We won't be able to give you hot fix directly on top a specific version but we will try to provide you a test build as soon as possible, should be in this week.

Thank you for the build. We tested with this build. The user objects don't leak anymore.

However we see the handle count in the main process is steadily going up when we repeatedly create and dispose web browser control. You could see the handle growth using the test application with this build.

Also, we have a question regarding dispose. We have a derived class from EO.Wpf.WebControl and in our derived class we have dispose. Prior to consuming this build we were calling the WebView.Close with force close and WebView.Dispose.

Our derived class code prior to consuming this private build:

public void Dispose()
{
var webView = this.WebView;

if (webView != null)
{
this.UnInitialize();
webView.Close(true);
webView.Dispose();
}
}

After consuming the private build, we are calling the Dispose on the EO.Wpf.WebControl, like this:
public new void Dispose()
{
var webView = this.WebView;

if (webView != null)
{
this.UnInitialize();
//webView.Close(true);
//webView.Dispose();
}

base.Dispose();
}

However we had to comment out the webView.Close(true) and webView.Dispose() to make it work with this build. Is the Webview associated with the WebControl closed properly in your WebControl's Dispose? If so, is it force closing? We had to force close it as without this we had issues.

We have e-mailed an updated version of our sample test application where the handle leak can be seen.

We tested with the new build and don't see handle leaks. Thank you so much for the prompt responses.

We have one open item that we need your input.

What is the proper way to close the WebView instance associated to the WebControl? Strange thing is when we close the WebView instance in our dispose method (like below) we see user objects leaking.

Following dispose method is in our derived class of Eo.Wpf.WebControl
public new void Dispose()
{
this.UnInitialize();

this.WebView.Close(true);
this.WebView.Dispose();

base.Dispose();

//this.WebView.Close(true); // we tried calling after invoking the WebControl.Dispose but still user object leaks
//this.WebView.Dispose();
}

There is no user object or handle leak when we don't close the WebView in our dispose, like this:
public new void Dispose()
{
this.UnInitialize();

base.Dispose();
}

We needed to do a force close of the WebView. Wondering how we could do this without causing user object leaks.

We have tested with the new private build and there are no leaks.

Thank you again for addressing this issue!