RFR: 8240466: AppJSCallback* apps launched by ModuleLauncherTest intermittently hang

[Ajit Ghaisas]

On Tue, 3 Mar 2020 22:51:43 GMT, Kevin Rushforth <kcr at openjdk.org> wrote:

> While testing JavaFX using gradle 6.3-nightly and JDK 14, I ran into what turned out to be a latent test bug in the
> AppJSCallback* apps that are launched by ModuleLauncherTest. The launched apps construct a WebView instance, obtain a
> WebEngine instance from the WebView, add a state listener to the WebEngine, load the web content, and then return from
> the Application::start method. The WebView instance is held a local variable, and so is subject to garbage collection
> once it goes out of scope when the start method returns.  In addition, the test apps did not check for successful
> launching of the application or successful loading of the web content, which led to the test suite hanging (else it
> would have been a simple test failure).  Note that I don't know (nor care) what changed in JDK 14 to make this more
> likely to occur, but since the test itself is demonstrably wrong, it needs to be fixed.  The main part of the fix was
> to make the WebEngine an instance variable. In order to make the test more robust, I also modified it to launch the
> application in another thread, and having the main thread check that the application launched successfully and that the
> web content was loaded successfully, after which I did the assertion check for the correct number of callbacks.  The 5
> different apps only differ from each other in the name of the class, the name of the package from which MyCallback is
> imported, and possibly the expected number of callbacks. I diffed AppJSCallbackExported.java against the other 4 test
> files and the diffs are essentially the same as they were before this change. Reviewers thus only need to review one of
> the tests in detail.  For example, here are the diffs between AppJSCallbackExported and AppJSCallbackUnexported:  $
> diff .../AppJSCallbackExported.java .../AppJSCallbackUnexported.java  37c37 < import myapp5.pkg2.MyCallback;
> ---
>> import myapp5.pkg1.MyCallback;
> 45c45
> < public class AppJSCallbackExported extends Application {
> ---
>> public class AppJSCallbackUnexported extends Application {
> 77c77
> <             Util.assertEquals(1, callbackCount);
> ---
>>             Util.assertEquals(0, callbackCount);

Marked as reviewed by aghaisas (Reviewer).

-------------

PR: https://git.openjdk.java.net/jfx/pull/134