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Why is MATLAB using 12% CPU at idle?

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Stephen Wilson
Stephen Wilson on 1 Aug 2020
Commented: Stephen Wilson on 6 Aug 2020
I just installed 2020a on a Thinkpad X1C5 laptop running Ubuntu 18.04. It is using ~12% CPU at idle.
This is a fast machine (core i7-7500U @ 4x 3.5 Gz) so no reason this should be happening. I run this version of MATLAB on other (desktop) machines on the same OS with no problems. I have also run other versions of MATLAB (most recently 2018a) on this laptop without seeing any significant CPU usage at baseline.
Everything is stock, e.g. built-in java, etc. The system is fully up-to-date, restarted, and so on.


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Stephen Wilson
Stephen Wilson on 6 Aug 2020
Further update: MATLAB technical support closed the case without being able to solve it. They declared this a "potential bug of MATLAB".
Stephen Wilson
Stephen Wilson on 6 Aug 2020
Further update: Bug is also present in 2019b, but is not present in 2019a.
Stephen Wilson
Stephen Wilson on 6 Aug 2020
Also, the bug exists even if no toolboxes are installed. My only workaround for now is to use 2019a.

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Answers (1)

Chidvi Modala
Chidvi Modala on 4 Aug 2020
The issue is specific to system settings, or due to a third party software installed in the system.
Many products in MATLAB rely on connector to maintain certain states. The connector creates and uses sockets. These sockets are being closed or altered by a third party software installed in the system, or specific system settings, due to which the CPU is spinning.
As the issue is system specific, you can try the following troubleshooting steps:
1) Change the power settings to High performance. To do this, open Power Options by clicking the Start button, and then clicking Control Panel. In the search box, type power options, and then click Power Options. Under Select a power plan, click Show additional plans, and then click High performance.
2) Download and run MSI Afterburner system utility to boost MSI graphics card. Please refer the link for more details on solving High CPU usage:
3) As a third party software is closing the sockets used by MATLAB connector, try killing processes (in Task Manager) which are of no use and are running in background.
If the above troubleshooting steps do not help resolve the issue, then the only workaround is to kill the MATLAB process, and restart the session.

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Stephen Wilson
Stephen Wilson on 4 Aug 2020
Thanks for your time but sorry, you seem to have missed the information that this is a linux system. But even so, this problem is 100% reproducible and happens immediately on launch of MATLAB, so restarting the session is not a workaround. Anyway, tech support is working on this now.

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