I updated Mongo from version 3.2.5 to 3.2.9 and after that Mongo has freezed my system by using all the CPU time.
There is nothing in Mongo's own logs but I can see that my own process has done both times a number of updates. But there has not been anything special with those updates as similar updates are done every 10 seconds.
There was about 24 hours between these problems so it won't occur very frequently. However, I had to downgrade Mongo back to 3.2.5 to see if this issues goes away.
I tried to search any open issues but I couldn't find anything relevant. As this is my production server and there is not much information about what is wrong, this might be quite hard to debug what is happening.