JavaFX 13 Webview hangs

Lior Yaffe lior.yaffe at
Tue Feb 11 15:21:25 UTC 2020

Test results:
OpenJFX 11 never hangs
OpenJFX 13 always hangs
OpenJFX 15ea the webview frame comes up empty but the runtime never hangs

The Java version has no effect.
The hang seems to occur in native code since there is no way to take a thread dump using jstack and the only possible action is to kill the process.
Is there any other logging or diagnostic you can suggest? 

February 10, 2020 7:24:54 PM CET Kevin Rushforth <kevin.rushforth at> wrote:    Can you also try JDK 11 with OpenJFX 13? I suspect it will not make    a difference (i.e., it will still hang), but it would be good to    confirm. And even more interesting will be the results of JavaFX    15-ea.


    -- Kevin

On 2/10/2020 10:17 AM, Lior Yaffe      wrote:

The problem does not reproduce when using JavaFX        11 regardless of the version of Java being used.        
I will try with Java 15ea

On Mon, Feb 10, 2020, 17:01          Kevin Rushforth <kevin.rushforth at>          wrote:

        And one last          thing to try: can you run it with the JavaFX 15-ea+1 build 
          and see if that makes a difference?

          -- Kevin

          On 2/10/2020 6:59 AM, Kevin Rushforth wrote:
          > Seems I missed your comment about it being hung to the          point you can't 
          > run jstack.
          > If you are using JDK 12 or later, you might try with JDK          11 and see if 
          > that makes a difference. It will help narrow it down to a          change in 
          > the JDK versus a change in JavaFX (although I suspect          it's a change in 
          > JavaFX).
          > -- Kevin
          > On 2/10/2020 6:40 AM, Kevin Rushforth wrote:
          >> A thread stack dump using "jstack" might be helpful.
          >> Also, what version of the JDK are you running?
          >> -- Kevin
          >> On 2/9/2020 4:07 AM, Lior Yaffe wrote:
          >>> My application is a Java application running a          Javascript/Html website
          >>> inside a JavaFX WebView. It was working stable          for several years with
          >>> various versions of Java and JavaFX.
          >>> As far as I can tell it is following best coding          practices such as 
          >>> running
          >>> all UI code in the JavaFX thread and as such.
          >>> Since upgrading to JavaFX 13 my application hangs          sporadically. When it
          >>> happens the website running inside the webview          becomes unresponsive and
          >>> displays an hourglass icon.
          >>> When the app hangs I cannot take a thread dump          using jstack or close 
          >>> the
          >>> application. I have to kill it.
          >>> The problem is reproduced on multiple Windows          workstations. It was 
          >>> never
          >>> reported or reproduced on Linux or Mac so there          is a chance it is 
          >>> Windows
          >>> specific.
          >>> When the app hangs the CPU is ideal so this is          not a busy loop.
          >>> Which diagnostic information can I obtain to          better understand this 
          >>> problem?

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