Affects Version/s: Master
Steps to Reproduce:
1. Set the following in portal-ext.properties:
2. Start Liferay and navigate to Control Panel > Server Administration > External Services.
3. Install Xuggler.
4. Restart Liferay.
5. Navigate back to Control Panel > Server Administration > External Services and enable Xuggler.
6. Upload and publish MP4 video.
7. Assert the video processing begins but never ends and the preview is not generated.
If you set dl.file.entry.preview.fork.process.enabled=false then the process will complete successfully. The issue is that a non-daemon thread is keeping the process from being destroyed.