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List:       openjdk-openjfx-dev
Subject:    Re: Platform dependent behavior in Platform.startup()
From:       Kevin Rushforth <kevin.rushforth () oracle ! com>
Date:       2019-07-31 13:03:44
Message-ID: bc7376f8-57ab-7aa6-7f44-096ddfa969c6 () oracle ! com
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While there is always a danger in calling a method that runs a lambda 
from a static init method, this seems like a case that should work. The 
current Mac implementation precludes returning from Platform::startup 
until after the Runnable passed into that method has completed and 
returned, which is not what was intended or expected.

Your solution seems like a good one, although it will need to be 
well-tested.

-- Kevin


On 7/31/2019 2:24 AM, Johan Vos wrote:
> Hi,
>
> A pattern I increasingly use is to add JavaFX functionality to existing
> non-JavaFX applications. Rather than adding a class that extends
> javafx.application.Application, I add some code to an existing class, like
> this:
>
> javafx.platform.Platform.startup(() -> {System.err.println("JavaFX
> started");});
> javafx.platform.Platform.runLater(() -> {Stage, Scene,... });
>
> I noticed that having Platform.startup() in a class initialiser works fine
> on Linux/Windows, but fails on Mac when a lambda is passed to startup().
>
> The reason for this is that on Mac, the main thread that starts Glass
> blocks until Glass has been started.
> But starting Glass also contains running the argument passed to startup().
> In case this is a lambda, this requires the encapsulating class to be
> initialized -- but initializing this class is happening already but blocked
> on Glass being started.
>
> The other platforms (Windows/Linux) are less strict. They don't block on
> Glass being started (including running the Runnable passed to startup)
> before they return.
>
> I created issue https://github.com/javafxports/openjdk-jfx/issues/542 for
> this and I propose to fix it via PR
> https://github.com/javafxports/openjdk-jfx/pull/543 which considers Glass
> to be started *before* the supplied runnable is executed.
>
> - Johan

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