Resolved High CPU and terrible performance with Wordpress sites with PHP 7.4.33

[danimora]

Server operating system version

CentOS Linux 7.9.2009 (Core)

Plesk version and microupdate number

Plesk Obsidian Version 18.0.48, last updated on Nov 17, 2022

Hi all,

Just sharing this here in case it is affecting someone else. Since the upgrade to PHP-FPM 7.4.33 all wordpress sites and very slow and extremely cpu intensive. Downgrading those sites to php 7.3.33 (that is "deprecated") speeds them up again. I'm talking about that a TTFB in 7.3 of 1s that goes up to 9s in 7.4.3.

I don't know how to rollback 7.4.33 to 7.4.0 but at least 7.3.33 mitigates the issue.

Am I alone with this?


PS. Moving them from Apache+FPM to NGINX+FPM also helps but I'm aware that this might be an issue on some sites because of .htaccess dependencies.

 

[mow]

Is the PHP configuration similar? Did you try PHP8.0 or 8.1?

 

[danimora]

Yes, php configuration was identical. I managed to reproduce it in a freshly installed Plesk instance with both PHP 7.3.33 and 7.4.33.

I made an attempt with PHP 8 but according to the wordpress 6.1 compatibility matrix PHP 8.x it is still in beta support. One of the sites was throwing 500 errors with php 8 and I did not pursued it further. But I'l try again in a sandbox and let you know.

 

[danimora]

PHP 8.0.25 has the same problem. Elapsed time to load the WP-admin dashboard:

9.0 seconds with PHP v8 or PHP v7.4.33
1.0 seconds with v7.3.33 or lower (7.4.0 works fine as well but i can no longer get it in plesk)

Both PHP 8.0.25 and PHP 7.4.33 share these two fixes in the reelase notes:

• GD:
  • Fixed bug #81739: OOB read due to insufficient input validation in imageloadfont(). (CVE-2022-31630)
• Hash:
  • Fixed bug #81738: buffer overflow in hash_update() on long parameter. (CVE-2022-37454)

 

[tomstar]

I am facing a similar proplem, fresh install of a vps with fresh worpress, ttfb > 2.5sec, running on 4 core 8GB RAM host with redis object cache. the site is currently not public so i am the only user testing the site, with php 8.0.25 i have 30% cpu usage on page refresh, 26.05% of that 30% by domains for process php-fpm.

looks like earlier this year someone has similar problems with newer php version:

Issue - Php 7 vs 8 performance issue

Hello everyone, i have two dedicated servers with plesk obsidian, both running debian 10 (10.5 and 10.11) and both hosting moderate traffic websites. I tried updating php version from the current 7.3.33 to more modern ones (7.4.30, 8.0.20, 8.1.7) but i have worse performance using them. The...

talk.plesk.com

 

[danimora]

I am facing a similar proplem, fresh install of a vps with fresh worpress, ttfb > 2.5sec, running on 4 core 8GB RAM host with redis object cache. the site is currently not public so i am the only user testing the site, with php 8.0.25 i have 30% cpu usage on page refresh, 26.05% of that 30% by domains for process php-fpm.

looks like earlier this year someone has similar problems with newer php version:

Issue - Php 7 vs 8 performance issue

Hello everyone, i have two dedicated servers with plesk obsidian, both running debian 10 (10.5 and 10.11) and both hosting moderate traffic websites. I tried updating php version from the current 7.3.33 to more modern ones (7.4.30, 8.0.20, 8.1.7) but i have worse performance using them. The...

talk.plesk.com

and if you test it with PHP 7.3, does it perform better?

 

[tomstar]

i have not installed PHP 7.3 because it is deprecated, so i am unable to test it right now. i'm not sure what the problem is, but the performance should be much better. i have enabled the new php 8 jit compiler, which helped a bit, but there is something else that is not performing right.

 

[tomstar]

currently i am using plesk on a VPS with 4 cores and 8GB RAM and SSD with 2.5sec ttfb with PHP 8.0.25, i just installed the same wordpress with the same theme and plugins on a shared hosting for testing, i have 250ms ttfp. i tested with PHP 8.0.23 and 8.1.10, i have no clue at the moment why it so much slower on plesk.

 

[Maarten]

What does PageSpeed Insights tell you about your website?

PageSpeed Insights

pagespeed.web.dev

Did you check the error_log and proxy_error_log files?

 

[danimora]

@tomstar

that is exactly what I'm experiencing with PHP 7.4.33 and PHP 8.x. Using PageSpeed and Newrelic what I see is a huge slowdown in the php processing that leads to TTFB of 2-3seconds per request.

I'm trying to install an additional handler with PHP 7.4.0 using this procedure. I'll let you know how it goes.

 

[tomstar]

error_log and proxy_error log are both only a warning because off ssl, but these are before i setup ssl, so no errors, PageSpeed Insights tells me ishould reduce the server response time

 

[ChristophRo]

Did you guys have the xDebug module for PHP active?
If yes, does the PHP7.4.33 performance revert back to normal, if you disable it?

 

[tomstar]

@ChristophRo xdebug is disabled on my PHP settings

 

[danimora]

Did you guys have the xDebug module for PHP active?
If yes, does the PHP7.4.33 performance revert back to normal, if you disable it?

xdebug is disabled on my PHP settings as well

 

[danimora]

error_log and proxy_error log are both only a warning because off ssl, but these are before i setup ssl, so no errors, PageSpeed Insights tells me ishould reduce the server response time

@tomstar do you have the newrelic extension installed?

 

[danimora]

I found the culprit. In my case it was the New Relic extension. Removing it fixed the issue.