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Re: Mysql 8.0: High CPU Usage
Posted by: Peter Brawley
Date: November 04, 2019 10:48AM

8.0 is a bigger, more ambitious package than 5.7, places a few percent more demands on mem & cpu.

The numbers you posted suggest a system running at the edge of hardware capacities.

To explore it further please ...

(i) post the result of ...

select engine,data,indexes,total
from (
    ifnull(engine,'TOTALS') as engine, 
    concat(data,' GB') as data, 
    concat(indexes,' GB') as indexes, 
    concat(tot,' GB') as total,
    if(engine is null,-1,tot) as ord
  from (
      round( sum(data_length)/1024/1024/1024, 2 ) as data,  
      round( sum(index_length)/1024/1024/1024, 2 ) as indexes,  
      round( sum(data_length+index_length)/1024/1024/1024, 2 ) as tot
    from information_schema.tables
    where engine is not null and engine not in('information_schema','performance_schema')
    group by engine with rollup
  ) sums
) list
order by list.ord desc;

(ii) post the results of running these queries in the mysql client program ...

show variables;

show global status;

select * from sys.memory_global_total;

substring_index(event_name,'/',2) as code_area,
sys.format_bytes( sum(current_alloc) ) as current_alloc
from sys.x$memory_global_by_current_bytes
group by substring_index(event_name,'/',2)
order by sum(current_alloc) desc;

concat(format(a.num * 100.0 / b.num,2),"%") bufferpoolfullpct
(select variable_value num from performance_schema.global_status
where variable_name = 'innodb_buffer_pool_pages_data') a,
(select variable_value num from performance_schema.global_status
where variable_name = 'innodb_buffer_pool_pages_total') b;

... and look for runaway mem use in the results of ...

select * 
from performance_schema.memory_summary_global_by_event_name
where event_name like 'memory/performance_schema/%';

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Written By
November 02, 2019 09:33AM
November 02, 2019 10:57AM
November 04, 2019 03:46AM
Re: Mysql 8.0: High CPU Usage
November 04, 2019 10:48AM

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