App freezing on Linux

David Hill David.Hill at
Thu Dec 3 20:05:27 UTC 2015

On 12/2/15, 3:29 AM, Bryan Buchanan wrote:
> I have a customer testing an FX app and more often than not, if the app is
> left open for a while (20 minutes or so), either the mouse ceases to work,
> or if it does work, when you click a field, or do something that should
> re-paint the window, the whole FX window goes totally grey and the app
> "disappears".
"disappears" would seem to indicate that the app has failed in some nasty fashion. The obvious question is if there is anything on the console/command line, or if there is any java crash dump in the launch directory (usually something like hs*.log).

If you have an indication that this is happening (mouse dying for example), then you try to force a jvm dump. The way I normally do it is to type ctrl-\ in the terminal window that is running the java command. The command line 'kill -QUIT <pid>" or "kill -3 <pid>" can also do this. In this case the dump goes to stdout, so you need something to capture this to a file. For this I tend to do something like:
      java <my usual args> 2>&1 | tee my_log.txt
This also grabs stderr as a bonus.

I suspect that there is something going on that is kicking to application thread main loop - something we try to protect against.

If you can capture a decent log, file a bug against it and I will likely be the one to root around in it to see if I can find anything that helps (there is a lot of stuff in one of those logs and it takes a bit to learn how to untangle one).


> I've tried starting with "-Dprism.verbose=true -Dprism.order=sw" and
> without these options, and it seems to make no difference.
> The system is Xubuntu 14.0.43,  kernel 3.13.0-71 running on a Gigabyte
> Brix, and Java 64 bit build 1.8.0_60-b27. I don't have this hardware in my
> office, but have run up a system with the same OS, kernel and Java, and
> cannot re-produce the problem.
> Are the any other command line switches, or debug flags that I can set to
> try and get a handle on why this is happening ?
> (Hope this is the right list for issues like this).

David Hill<David.Hill at>
Java Embedded Development

"A man's feet should be planted in his country, but his eyes should survey the world."
-- George Santayana (1863 - 1952)

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