High CPU Load After Permission Changes On NI VLM

Updated Apr 7, 2023

Reported In


  • Volume License Manager

Issue Details

I am using a lot of NI software on several hundred computers. I manage the licenses with the NI Volume License Manager (VLM). There is times where users cannot connect to the VLM and pull a license accordingly.
During these times I can see a high CPU-load on one core of the server which is caused by the nilm.exe process. 

How can I solve this issue?


This issue is a known bug with the FLEXlm software used in our licensing technologies. Please see Additional Information section for more insight. While we are collaborating with the component vendor to fix the issue, currently there is no fix to the issue. To avoid the issue, use one of the workarounds mentioned below. For all workarounds new license files are needed, please contact NI Support for more information.
  • Using a backup-server that will bounce-in while the first server is not reachable because of the issue
    • In order to implement this an appropriate IT structure is necessary.
    • This workaround will not prevent the issue from appearing, but provide a backup system for ensuring that all clients can continue working.
  • Using several servers by splitting the license file for reducing the number of clients per server
    • This would prevent the issue from appearing as it is depending on a critical number of clients set-up and connected.
    • All clients can be divided into organizational groups at different locations which makes it easier to distribute them to the different servers. 
    • A well-considered distribution strategy can offer further advantages such as an existing free space in time where maintenance work can be carried out on the servers.
    • On each server it should be checked regularly if the critical number of clients has been exceeded. If this is the case a new server must come into place.
  • Handling new permission requests through a new server while freezing the configuration of the old server
    • The issue only appears on a server if there are permission changes to be applied. If the configuration of a server is not changed anymore the issue won't appear.
    • This workaround can also be used for having a smooth transition to the second workaround. The effort for setting up new servers is minimized.
    • Make sure that the automatic permission handling is deactivated on the current server (see Additional Information)
    • Any new user or computer should be directed to use the new server.
    • New license files for all servers are needed.

Additional Information

  • The issue typically appears after around 800 clients or more are added to the VLM. The exact number of clients varies depending on hardware specifications and license file configuration. It is also needed that a high number of the clients are connected to the server for the issue to be seen. High load will last for several hours, how long exactly depends again on several influencing parameters.
  • The high CPU load is only a symptom of the cause. Other possible symptoms are:
    • Freeze of the VLM Software
    • NI Software cannot be used properly for any client
  • The trigger for the issue is basically applying permission changes for clients. There is two options how this can be noticed:
    • If the automatic permission handling in VLM under Tools > Preferences is activated, the issue will appear sporadically: 
  • If automatic permission handling is disabled, whenever permissions are handled manually the issue is caused when the Apply Changes button is pressed: 
  • Note: Shifting the use of the Apply Changes button into a time where the fewest clients are using the software can help minimizing the impact that this issue has. There is currently no way to schedule applying any changes.