Mysql process CPU usage over 90% after update

[Zeljko]

Hi guys,
Two weeks ago I have updated The Events Calendar (from 4.5.9 to 4.6.3) + The Events Calendar PRO (4.4.17 to not sure which) on WordPress 4.8.3. After update completed, I got notice from hosting that my database is causing mysql process to put CPU usage on over 90%. I tried disabling plugins one by one and noticed if I disable Event Calendar, CPU usage drops back to normal (under 5%). Reverting plugin to older versions didn’t helped until I restored complete backup of the whole page.
Yesterday I updated WP to 4.9 and all other plugins except Event Calendar. Everything worked fine. Couple of hours age, I also updated Event Calendar to 4.6.6 and Event Calendar Pro to 4.4.19 and same issue with mysql process happened.
I needed to restore page from backup again to use it normally again…

Do you have any ideas what could be causing the problems?

Thanks in advance!

[Victor]

Hi Zeljko!

Thanks for reaching out to us. Let me help you with that issue.

Let me first note that we’ve had a couple other users experiencing a slowdown in performance for our latest release of Event Calendar Pro 4.4.19. Our devs are already working to improve this, so I will link this thread to the report and we’ll notify you as soon as we have an update for it.

In the meantime, the workaround we’ve found so far is staying at Event Calendar Pro version 4.4.18. If you still experience performance issues in that version, then this could be related to something different.

How many events, venues and organizers do you currently have? Do you experience a slow down in performance in specific pages? Please let me know which ones.

We have a great article that will get you started on Performance Considerations you should know about. After that, if you decide to implement a caching system then you can move to these articles: Caching: What, when and how and Caching month view HTML in transients

Finally, there is a good article George put up here that groups a set of developer plugins. It’s a bit more technical than the others but will definitely be of help if you are into development.

Let me know how it goes.

Thanks,
Victor

 

[Zeljko]

Hi Victor,

There are currently 29240 events, 7608 venues and 723 organizers. Pages are working fairly correctly, biggest issues with pages were after updates.Dashboard can be sluggish from time to time.

The Month View cache option is enabled and there is also W3 Total Cache plugin installed from the first day of using The Events Calendar.

Changing any of cache options didn’t helped after update. Only thing that helps return things to normal is restoring server to pre-update state. Even if I only downgrade plugin, issue remains until database is restored to the pre-update state.

Also, I noticed bug related to Community Events addon. Default site language is German. If admin account is set (in the profile settings) to the English language, “hinzufuegen” link is changed back to “add”. Setting language back to “Site default” or German restores link back to “hinzufuegen”.

[Victor]

Hi Zeljko!

Thanks for coming back with that information.

I ran a few tests in your site’s main events page. The first time I visited the page, the TTFB (time to first byte) was more than 7 seconds. After that first time, the TTFB dropped to a few milliseconds. This drop in time is probably because the page has been cached by W3 Total Cache, which is great for the front-end of your site.

The slow down in performance you experience in the wp-admin is because there is no caching in it. You are probably getting a poorer performance after updating the plugins, because the cache is being cleared and needs to be rebuilt again, thus needing more resources and time.

The number of events and venues in your site is a really high number of posts to consider when dealing with performance issues, and is mostly sure the main reason for your site’s performance. You could try removing events that are from far in the past and venues that are no longer used to lower the amount of posts.

If that is not an option, then you could get in touch with your hosting provider and see if they can offer a hosting environment with higher resources.

I truly sympathise with your situation as I have also experienced performance issues in the past and know they can be really hard to tackle, specially when dealing with a high number of posts.

I hope this helps. Let me know if you have any follow up questions and I will try to help as much possible.

As for the language issue, could you please open a new topic for it? This will help us keep things organized and make sure we give each topic its proper attention. We doing so, please share a screenshot of the issue so we can get a sense of the what you are experience so we can try to reproduce on our end.

Thanks,
Victor

[Zeljko]

Hi Victor,

Thanks for your response. At the moment, deleting events is not a option. Current server has Intel i7 6700 CPU and 32GB of RAM. Not quite sure about hard drives but they should be SSD. Server has ISPConfig 3.1.0 control panel.

Have you noticed any difference in performance on nginx and apache servers? Could there maybe be issue with nginx?

[Jada Jarillo]

In case it’s of any help, we had this issue as well. We have 8k events, 1.6k venues. Upon activating the Events Calendar plugins, cpu use by mysql shot way up–I saw it break 400% (we are on virtual server). I have rolled back to Pro v4.4.18 and things are steady. Mysql CPU use is still on the high side, but it’s not constantly maxed out any more and the site is staying online.

We are ok to delete old events, so I am going to work on that now and hopefully that will further improve resource use.

[Victor]

Hi Zeljko!

Thanks for following up with this. I’m not an expert in servers but your server setup seems powerful to me.

We are not aware of any issues regarding NGINX.  It seems that NGINX handles better multiple/simultaneous requests (NGINX was created with this purpose: to handle a larger number of clients at the same time). Here’s an interesting article one of our team members shared with me about the difference between NGINX and Apache servers > https://www.digitalocean.com/community/tutorials/apache-vs-nginx-practical-considerations

As you are dealing with a high number of posts, this means that your database is big and is probably slowing down your site. What I would recommend is installing the Query Monitor plugin > https://wordpress.org/plugins/query-monitor/ to find the slow database queries performed. This will give you more information of where you should try to optimize things.

Point 6 of the following article > https://wpengine.com/blog/page-speed-wordpress-performance/ gives a really good tip about database optimization you should also know about.

We always suggest you setup a dev/staging site so you can make all these tests without disrupting the live site. We also encourage to make a full backup of your site, both database and files so in case something goes wrong you can always restore your site.

I hope that helps!

Hi Jada! Thanks for chiming in and sharing your experience about this subject 🙂

It’s a good idea to downgrade to Events Calendar PRO version 4.4.18 if you have that many events and are experiencing a slow down in performance. As I mentioned before, we are aware of this performance issue in version 4.4.19 and we are actively working to improve this.

Feel free to follow the updates in this thread as we will notify when a fix for this has been released.

If you need further assistance please open a new topic so we can help you further with any questions you may have.

Best,
Victor

[Zeljko]

Hi Victor,

Any news with the update?

[Victor]

Hi Zeljko!

I’m sorry for the delay in getting back to you.

I have just checked the report for the performance issue and it seems a filter is going to be added to prevent the large SQL query from being called that causes that specific performance issue in Events Calendar PRO 4.4.19.

I can’t commit to a date for when this will be available, but there is a chance that will be included in our next maintenance release. We will keep you posted about it.

Thanks for your patience.

Best,
Victor

[Nico]

Hi there,

Just wanted to share with you that a new maintenance release (for the Week of 7th January 2018) is out, including a fix for this issue :slightly_smiling_face:

Find out more about this release → https://theeventscalendar.com/maintenance-release-week-7-january-2018/

Please update the plugins and let us know if the fix works for your site,
Best,
Nico

[Support Droid]

Hey there! This thread has been pretty quiet for the last three weeks, so we’re going to go ahead and close it to avoid confusion with other topics. If you’re still looking for help with this, please do open a new thread, reference this one and we’d be more than happy to continue the conversation over there.

Thanks so much!
The Events Calendar Support Team

[Author]

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