We updated our busy Drupal 7.50 site from Panels 7.x-3.5 to Panels 7.x-3.6 on August 17th as soon as it was released. We use Panels throughout our site, and almost every page is rendered through a page template.

We immediately noticed a significant slowdown in non-cached, non-Anonymous responsiveness of the site, and this correlates to a significant change in the shape of Drupal's MySQL usage, illustrated in this graph showing average MySQL connections over the period before the upgrade, after the 7.x-3.6 upgrade, during a period where we reverted, as a test, to 7.x-3.5, and after subsequent an upgrade to 7.x-3.7:

Amazon RDS DB Connections graph

We're interested in understanding the root of this issue, and steps we can take to mitigate it: in the move from 7.x-3.5 to 7.x-3.6 is there an expected increase in database usage in a way that would result in what we're seeing?

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RDS · AWS Console-1.jpg295.52 KBreinvented
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reinvented created an issue.

reinvented’s picture

reinvented CreditAttribution: reinvented as a volunteer commented

What further research has shown is in the days since we created this ticket was that the issue with Panels 3.6 and 3.7 vs. Panels 3.5 is that the demand on our MySQL server to rebuild a page when it expires from the cache is significantly greater.

We've correlated spikes in MySQL connections with the expiration of pages from the cache. While there are no long-running queries being logged, we're seeing significant connections in the Sleep state associated with the spike in connections and the slowdown of the site.

It would be helpful to us to be able to understand more about what changed from Panels 3.5 to Panels 3.6/3.7 in terms of the weight of building a Panels-managed page.

reinvented’s picture

reinvented CreditAttribution: reinvented as a volunteer commented

We updated to Panels 7.x.3.8 and Ctools 7.x.1.11 and the issues we've been having remain: significant increase in MySQL load and a resulting increase in site latency. Reverting to Panels 3.5 solves the issue.