Symptoms

Suppose you see periods of high CPU load (reaching 100%) caused by the K2 blackpearl host server service process (K2HostServer.exe). The high CPU load appears temporarily and sporadically and cannot be reproduced intentionally.
 

Diagnoses

Apart from insufficient hardware capacity, the other reason of such issue can be some misbehaving or poorly designed process.
Verify if any of running process instances have extremely large state size. In case you have at least one such process, which has very large state size (for example 6MB) you will observe high CPU load whenever K2 server performs loading of this state into memory.
Large state size can be result of infinite looping in the process, which may be necessary in certain scenarios. If this is the case, you may consider restarting such instance via IPC over regular interval instead of running instance infinitely and decrease timeout values.
 

Resolution

Use details outlined above to investigate and address this issue.