Groups/Groups Forums Compatibility with Caching Solutions

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Awesome set of plugins! Thank you for all the great work! I’m hoping to get some advice about using plugins from the Groups ecosystem with server-side caching solutions. Our hosting provider (SiteGround) offers three “levels” of caching to help speed up site performance–static, dynamic and memcached. Over the past few weeks, we’ve seen instances where restricted Recent Forum Topics that are normally displayed only to defined groups of logged in users remain visible in a sidebar widget even after a user has logged out and returned to the page that features the list. The topics remain visible even after the page is refreshed and the browser cache is cleared by the visitor. However, the topics disappear after the server-side cache is purged and the visitor refreshes the page. Based on our testing, the issue does not appear to occur with static and/or dynamic caching enabled, but it does appear to occur when we activate memcached (https://memcached.org/about). For now, we’ve disabled memcached, but are wondering whether (1) there’s a way to take advantage of it without breaking things and (2) whether there might be any other known issues related to caching that we should be aware of or test for. Thanks in advance!

One Response to Groups/Groups Forums Compatibility with Caching Solutions

  1. Kento December 2, 2019 at 2:19 pm #

    Hi!

    Thank you very much for your kind comment on the tools, I’m very happy to hear this!

    Based on what you describe and looking at Siteground’s Memcached option, you would have to leave it off.

    The reason for this is that any caching which does not distinguish between plain visitors and privileged members will most likely present unwanted content to either of those groups. The most basic variation of this happening is when users who are logged in get pages with inconsistent content, seeing what plain visitors would see when they should see more specific content. The issue stems from the caching system providing the same content that it has in cache to both connected (logged in) and unconnnected (not logged in) viewers.

    For many caching systems you have the option to turn off caching altogether when you are presenting content to a user who is logged in. They would only serve cached content to normal visitors.

    For the case with Memcached used by Siteground, they would actually need to refine their implementation and give you the choice to not use Memcached when a privileged member is visiting the the pages. Or even better, integrate with Groups and make cached content group-specific. I’m not really so familiar with all their caching options, but it wouldn’t hurt to ask them if they would be able to enhance their options or if they already have one, they can point you to the right settings.

    Cheers

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