Seems to be the same problem as this one: https://forum.renoise.com/t/vsts-on-64-bit-linux/45319
Libc’s “sem_post” crashes after the “sem_open” succeeded. Never could replicate this here and unfortunately also have no clue why this is happening.
Are you using Ubuntu’s standard kernel + standard settings, or have to applies some tweaks to optimize Ubuntu for audio?
Can anyone else replicate this on Ubuntu 15.10?