Symptoms
- Server is slow
- While trying to install packages the following error is shown:
Waiting for cache lock: Could not get lock /var/lib/dpkg/lock-frontend
- SSH session is slow
- Websites fail with 502 error
- The Monitoring extension shows a high value for CPU steal:
Cause
Another virtual server that is created on the same hypervisor that the Plesk virtual server resides on is stealing a very big chunk of CPU time that is meant for the virtual server, due to which the virtual server is unable to use the resources that it should be able to use at all times.
CPU steal time is the percentage of time the virtual processor of the virtual server waits for a real physical CPU to become available, while the CPU of the hypervisor on which it resides is servicing the virtual processor of another virtual server.
A large amount of CPU steal time can make the server and the websites slow and/or inaccessible.
Resolution
Issues with CPU time can be resolved only on the end of the hypervisor that holds the virtual server on which Plesk is installed. Please contact your service provider to assist with managing the server's resources.
Note: CPU steal time on a Plesk server can be viewed using the Monitoring extension by checking the CPU total usage in Monitoring tab.