Conflict on object-cache.php

Hi @didierjm,

Thanks for reaching out. The object-cache.php file generated by the Performance Lab plugin doesn’t interfere with any third party plugins object caching features, or the W3 Total Cache’s object-cache.php file (which they place inside the wp-contentw3-total-cache/wp-content/ directory. It’s used to measure server timings in WordPress as early as possible, with details then added to a users Site Health information.

You’ll find more on this by visiting the plugins GitHub, where there is a mention on why the plugin generates an object-cache.php file.

Within the Performance Lab generated object-cache.php file there is also a PERFLAB_DISABLE_OBJECT_CACHE_DROPIN constant. If you set this to true this will prevent the plugin from updating the file, to ensure there is no conflict if you’re finding another plugin updates the same file. If applied, however, you won’t have the server timing feature active.

Let me know if you have any further questions on this.

Sorry, but that’s not true, by default…

I now have 2 conflicting files with same name, one renaming the other depending on who’s last:

ObjectCache Version: 1.4
W3 Total Cache Object Cache

Object cache drop-in from Performance Lab plugin.
@ package performance-lab
@ since 1.8.0

Both are located in /wp-content/

When the one that comes with Performance Lab is active, W3TC gets unconfortable… offering to disable object caching and/or deleting the conflicting file…

SIncerely

DJM

• This reply was modified 2 years, 3 months ago by cybeardjm.

FYI, support at W3TC confirms the problem…

DJM

Hi @didierjm,

Thanks for the update, and apologies if the W3 Total Cache plugin is inserting the object-cache.php file in the wp-content directory. In my case I located this within it’s own directory, although I didn’t look into this or check this further.

I’ll perform some additional checks on this now, and open a GitHub issue if I once I can recreate the same, with the steps to recreate and additional insights.

I’ll report back to you here after some additional testing. Thank you!

I’m seeing the same issue but with Object Cache Pro. Performance Lab and Object Cache Pro keep replacing each other. I wonder if Performance Lab should be a bit more conservative about this — if it detects another object-cache drop-in, sure, fire a warning in the health check screen, but maybe don’t replace the pre-existing one without explicit user consent.

@jamesosborne it’s possible that, if Object Caching is not activated in W3TC, the file stays in a kind of “repository”.

But as I had this option ON in my setup, it was in the wp-content directory. And throught the many tests I did (incl. installing/desinstalling both plugins., one by one or both at once…), it’s normal behavior for the plugin…

Once again, the team @ W3TC confirmed the problem…

Might be, you could rename your file to something different, or at least like @desmith wrote above, not write over or just rename existing files without warning and taking the context into account…

Looks a bit “unprofessional”…

DJM

Hi @didierjm,

From testing this further I can confirm the same behavior as you reported. Thanks for highlighting this. The expected behavior of the Performance Lab plugin is to rename any third party plugin inserted object-cache.php file, so as not to impact any object caching settings. I’ve created the following GitHub issue where we can investigate this further:

https://github.com/WordPress/performance/issues/612

Feel free to subscribe to that GitHub issue for updates on this, and many thanks for bringing this to our attention.

THX

DJM