Hi Ceki,

I've updated the Environment section of the bug report. I'm running under Windows 10.

Yes, the semaphores are used to limit the number of concurrent threads.

If you want to reproduce the bug even faster, you can make the following changes:

• Change maxFileSize to 1MB and totalSizeCap to 10MB in logback.xml
• Decrease the number of semaphore permits to 50

When I run this, I get a deadlock after a single line of output.