High CPU usage

There are about 1000 users concurrently access my website.So i have hosted my web site on OVH server with below specification
CPU
Intel(R) Xeon(R) CPU E5-1620 v2 @ 3.70GHz
Cores : 8
Cache : 10240KB

RAM
8x 16384MB
Disks
2 x 2000 GB
Motherboard
X9SRE/X9SRE-3F/X9SRi/X9SRi-3F

Kernel version
3.14.32-xxxx-grs-ipv6-64

but sometimes my cpu usage is getting high,one day it was increased to top level.In SSH mysql server is on the top.Today i checked my error_log file and found below mention error at every time.

[26-Jun-2016 16:50:20 UTC] WordPress database error You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ‘WHERE AND comment_parent IN (18,19,24,28) ORDER BY comment_date_gmt ASC, comme’ at line 1 for query WHERE AND comment_parent IN (18,19,24,28) ORDER BY comment_date_gmt ASC, comment_ID ASC made by require(‘wp-blog-header.php’), require_once(‘wp-includes/template-loader.php’), include(‘/themes/Newspaper/single_template_5.php’), comments_template, require(‘/plugins/intensedebate/intensedebate-comment-template.php’), id_get_original_comment_template, comments_template, WP_Comment_Query->__construct, WP_Comment_Query->query, WP_Comment_Query->get_comments, WP_Comment_Query->fill_descendants

so that i am unable to find the exact file which contains this error.Can you please help me to solve that problem.I want to know about my server,is it enough for this kind of traffic or not.Still i can’t understand where is the problem,in my website or the server.Please help to solve that problem.Thank you.

Its your server, maybe has a bad configuration or its your website whit bad configuration. In your server you need to use a cache system and in your web a cache plugin to manage 1000 users online, optimize databases and everything on your site, reduce request to mysql, etc.

Btw, for more than 300 simultaneus users online you need a server whit SSDs and not HDD 😛

Thank you for answering me an what about this issue

26-Jun-2016 16:50:20 UTC] WordPress database error You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ‘WHERE AND comment_parent IN (18,19,24,28) ORDER BY comment_date_gmt ASC, comme’ at line 1 for query WHERE AND comment_parent IN (18,19,24,28) ORDER BY comment_date_gmt ASC, comment_ID ASC made by require(‘wp-blog-header.php’), require_once(‘wp-includes/template-loader.php’), include(‘/themes/Newspaper/single_template_5.php’), comments_template, require(‘/plugins/intensedebate/intensedebate-comment-template.php’), id_get_original_comment_template, comments_template, WP_Comment_Query->__construct, WP_Comment_Query->query, WP_Comment_Query->get_comments, WP_Comment_Query->fill_descendants

Which file that I have to edit to fix above mention error.so how can optimus mysql.I used w3 total cache plugin.but after that my cpu usage is getting high.any recommned plugin to use for optimus mysql.I know that I asked you a lot of questions.So I don’t have another option to do.Please help again.Thank you.

Today also i got a problem in my website, it gets a lot of time to load.in today error i got these errors

1.
[27-Jun-2016 03:29:43 UTC] PHP Warning: Cannot modify header information – headers already sent by (output started at /home/nethnews/public_html/index.php:2) in /home/nethnews/public_html/wp-includes/load.php on line 155

2.
[27-Jun-2016 03:34:16 UTC] WordPress database error You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ‘WHERE AND comment_parent IN (15) ORDER BY comment_date_gmt ASC, comment_ID ASC’ at line 1 for query WHERE AND comment_parent IN (15) ORDER BY comment_date_gmt ASC, comment_ID ASC made by require(‘wp-blog-header.php’), require_once(‘wp-includes/template-loader.php’), include(‘/themes/Newspaper/single_template_5.php’), comments_template, require(‘/plugins/intensedebate/intensedebate-comment-template.php’), id_get_original_comment_template, comments_template, WP_Comment_Query->__construct, WP_Comment_Query->query, WP_Comment_Query->get_comments, WP_Comment_Query->fill_descendants

on 24th this error

[24-Jun-2016 08:07:04 UTC] PHP Fatal error: require(): Failed opening required ‘/home/nethnews/public_html/wp-includes/taxonomy.php’ (include_path=’.:/usr/lib/php:/usr/local/lib/php’) in /home/nethnews/public_html/wp-settings.php on line 167

I don’t know what to do please help me if you can.Thank you