Title: Object cache problems back?
Last modified: August 21, 2016

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# Object cache problems back?

 *  [David Anderson / Team Updraft](https://wordpress.org/support/users/davidanderson/)
 * (@davidanderson)
 * [13 years ago](https://wordpress.org/support/topic/object-cache-problems-back/)
 * In the days of W3 Total Cache 0.9.2.8, I used to see a lot of users (for the 
   UpdraftPlus plugin, which I develop) who had their transients vanish. Transients
   set with a 9-hour expiry were not found when requested 5 minutes later with get_transient().
 * This problem seemed to go away when 0.9.2.9 was released.
 * But now, it seems to be back – I’m seeing the same symptoms in users’ reports/
   logs; some minutes after setting a transient that lasts for 9 hours, we attempt
   to retrieve it with get_transient() and there’s nothing there.
 * I’m wondering if this item in 0.9.2.10 has anything to do with it?
    “Improved
   Object Cache purge policy performance”
 * [http://wordpress.org/extend/plugins/w3-total-cache/](http://wordpress.org/extend/plugins/w3-total-cache/)

Viewing 9 replies - 1 through 9 (of 9 total)

 *  [bikeboy888](https://wordpress.org/support/users/bikeboy888/)
 * (@bikeboy888)
 * [13 years ago](https://wordpress.org/support/topic/object-cache-problems-back/#post-3781169)
 * My object cache is not clearing also.
    I am using page cache – disk enhanced 
   object cache – disk browser cache – on Garbage collection and expires header 
   lifetime set to 1800 secs on all options.
 * Cron GUI plugin shows tasks to clear cache in cron list, but the files are never
   cleared…and baloon in size.
    Manual clearing of cache from admin button works.
   I know its not only me….any updates on this
 * latest versions of w3tc and WP
 *  Thread Starter [David Anderson / Team Updraft](https://wordpress.org/support/users/davidanderson/)
 * (@davidanderson)
 * [13 years ago](https://wordpress.org/support/topic/object-cache-problems-back/#post-3781170)
 * That’s a different problem to this one. The problem in this thread is that transients
   set during cron runs with update_transient are sometimes no longer found (returns
   nothing with get_transient) during later cron runs.
 *  Plugin Contributor [Frederick Townes](https://wordpress.org/support/users/fredericktownes/)
 * (@fredericktownes)
 * [13 years ago](https://wordpress.org/support/topic/object-cache-problems-back/#post-3781246)
 * The improvement was that the object cache is not purged as much anymore.
 * When do you set the transients? Is it in backend, frontend, logged in, not logged
   in? Are users calling empty cache?
 * Emptying Object Cache or all caches, the engine used for transients will remove
   the transients as well.
 *  Thread Starter [David Anderson / Team Updraft](https://wordpress.org/support/users/davidanderson/)
 * (@davidanderson)
 * [13 years ago](https://wordpress.org/support/topic/object-cache-problems-back/#post-3781249)
 * Hi Frederick,
 * No emptying of the object cache is involved.
 * My code runs during an action called via wp_schedule_single_event(). It sets 
   a transient with update_transient(). The action itself re-calls wp_schedule_single_event()
   to invoke itself again 5 minutes later. This can happen various times. The re-
   called code calls get_transient() to get the data that was set earlier with update_transient().
   Sometimes, get_transient() returns nothing (false/null).
 * The problem is random, i.e. does not happen every time. However, testing it many
   times on various different sites establishes one common factor – the problem 
   only ever occurs on site’s where W3 Total Cache’s object cache is active, and
   never occurs when it is turned off.
 * David
 *  [rclai](https://wordpress.org/support/users/rclai/)
 * (@rclai)
 * [12 years, 12 months ago](https://wordpress.org/support/topic/object-cache-problems-back/#post-3781268)
 * I am getting a problem with transients as well when I set a transient in a function
   hooked to a shortcode. I try to retrieve the transient in an ajax request, and
   it’s not there. This problem doesn’t happen when I have object caching off.
 *  Plugin Contributor [Frederick Townes](https://wordpress.org/support/users/fredericktownes/)
 * (@fredericktownes)
 * [12 years, 11 months ago](https://wordpress.org/support/topic/object-cache-problems-back/#post-3781270)
 * I assume you meant set_transient? And also that is just together with wp-cron?
   Which cache engine do you use? We’ll look into cron and transients some more.
 *  [Birgir Erlendsson (birgire)](https://wordpress.org/support/users/birgire/)
 * (@birgire)
 * [12 years, 9 months ago](https://wordpress.org/support/topic/object-cache-problems-back/#post-3781291)
 * I got similar problems with `set_transient()` with version** 0.9.3** installed.
 * The function `get_tranisent()` was always returning `false` no matter what.
 * By reverting back to** 0.9.2.9** it started working normal again.
 * **ps:**
 * My setup is:
 * page cache – apc
    object cache – apc browser cache – on
 *  Thread Starter [David Anderson / Team Updraft](https://wordpress.org/support/users/davidanderson/)
 * (@davidanderson)
 * [12 years, 9 months ago](https://wordpress.org/support/topic/object-cache-problems-back/#post-3781292)
 * Hi birgire,
 * This thread is a bout a different problem, which happens during WP_CRON, and 
   exists in 0.9.2.9 too. I’ve seen your problem (APC/outside WP_CRON/0.9.3) too,
   but you should start a separate thread for it as it’s a separate problem.
 * David
 *  [Birgir Erlendsson (birgire)](https://wordpress.org/support/users/birgire/)
 * (@birgire)
 * [12 years, 9 months ago](https://wordpress.org/support/topic/object-cache-problems-back/#post-3781293)
 * Hi, David Anderson
 * ok, sorry about that.
 * I haven’t used the Updraft plugin and you didn’t mention wp-cron in your question
   and it sounded very similar to my w3tc object cache + transient problem 😉
 * cheers
 * ps: any way I found this
 * [http://wordpress.org/support/topic/bug-in-apc-object-cache-wp_cache_set-making-it-fail](http://wordpress.org/support/topic/bug-in-apc-object-cache-wp_cache_set-making-it-fail)
 * that might be related to the problem I’m seeing and/or related to yours?

Viewing 9 replies - 1 through 9 (of 9 total)

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 * Last activity: [12 years, 9 months ago](https://wordpress.org/support/topic/object-cache-problems-back/#post-3781293)
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