VM goes into 100% CPU utilization

[noha]

Since last week I was noticing on our production system that in the morning one to four vms are using 100% CPU. The date matches the new release of the vm 1.2.1 and the a few days it tool for us to make a new release including that. I've search the process list in the image for something strange but could only find normal processes and number. I then made our deployment be able to go back to an earlier vm. So I moved our system back to 1.2.0 vm and the effect disappeared. I've watched this now for a few days. Before every day there was vms having 100% CPU and now there is none. At this point this is sadly the only context I can provide. To us the introduction of epoll() might be the nearest possible culprit. The images go most probably in 100% CPU mode at night because there the backup runs are happening with a high I/O load. I will try to preserve a manual triggered crash.dmp file. This needs a bit of effort due to the ephemeral nature of docker containers. This is the best bet to find something in crash.dmp as I don't know how it can be reproduced. So if you have better ideas about data I should collect please tell