Why is mysqld CPU heavy?

Question

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There are:
5 online stores with low attendance. Good hosting. Periodically huge brakes on the site due to the fact that mysql loads the percentage under 100%. There are no formal procedures. The problem is old and has been going on for a long time. My qualifications are not enough to understand what the cant is (maybe not in Bitrix at all, but in the server settings).
Tell me where to dig? Or recommend a specialist. Thank you.

Answer 1

well, first show mysql config

Answer 2

Under admin at the time of the brakes:
SHOW PROCESSLIST
and look for a hung request

Answer 3

Enable profiling.
Make a conclusion for yourself on each page and walk around the site, see which queries are taking a long time to complete.
Ordinary slowlog sometimes will not show that some request is looped on your page and is executed several dozen times.

Answer 4

Not all good hosting services are created equal. VPS/VPS? Random loading usually means disk drawdown.

Answer 5

Did you try to take the config that 1C made himself with slight changes in the distribution of RAM?
Is the result of the top command, wa normal?
And so in bitrix, requests are not particularly easy, when the online store wrote there, it completely abandoned infoblocks.