Why is the License Manager using 100% CPU at times?

Sometimes the License Manager, specifically the MLM process, is using up 100% of CPU available to it. It can take a few seconds to several minutes. I have a larger Options file, but still within the limits: less than 4000 characters per line, no more than 10,000 lines in total. I have several groups defined according to their IP address with HOST_GROUP and use RESERVE to reserve a certain number seats for different groups.

Clients may get License Manager Error -139 (Timeout) during the high CPU load.

Answer 1

[MathWorks Support Team]

Reserved seats with the RESERVE keyword are computationally expensive when used in combination with IP addresses. When the number of reserved seats for a product and the total number of IP addresses in the Options file reach a certain limit, a license checkout of that product will cause MLM to go to 100% CPU usage.

The more IP addresses are defined in total, the lower the number of reserved seats can be before CPU usage goes up. The duration of high CPU usage seems to depend on the number of reserved seats. It can range from a few seconds when only a few seats over the limit, to several minutes when much over the limit.

Shutting down the license manager will not terminate the overloaded MLM process. You can either wait it out or kill the process manually.

There are no known direct workarounds. The number of reserved seats has to be decreased, at least for the product with the highest number of reserved seats, as that is the most likely culprit. Possibilities include:

- Faster server.

- Use host names or user names instead of IP addresses.

- Use INCLUDE and MAX to implement similar licensing restrictions.