Title: Yac Object Cache Author: laruence Published: شتنبر 2, 2026 Last modified: شتنبر 23, 2026 --- Search plugins ![](https://ps.w.org/yac-object-cache/assets/banner-772x250.png?rev=3677662) ![](https://ps.w.org/yac-object-cache/assets/icon-256x256.png?rev=3677662) # Yac Object Cache By [laruence](https://profiles.wordpress.org/laruence/) [Download](https://downloads.wordpress.org/plugin/yac-object-cache.1.4.0.zip) * [Details](https://ary.wordpress.org/plugins/yac-object-cache/#description) * [Reviews](https://ary.wordpress.org/plugins/yac-object-cache/#reviews) * [Installation](https://ary.wordpress.org/plugins/yac-object-cache/#installation) * [Development](https://ary.wordpress.org/plugins/yac-object-cache/#developers) [Support](https://wordpress.org/support/plugin/yac-object-cache/) ## Description [Yac](https://github.com/laruence/yac) keeps the cache in a shared memory segment accessible to all PHP workers, so a read is a hash lookup in local memory — no cache server, no socket, no network. **Highlights** * **Fast.** No socket, no network, no global lock, so throughput scales with workers. Yac’s own [benchmark](https://github.com/laruence/yac#benchmarks) measured 13x- 70x higher ops/s than APCu and 170x-730x higher than local Memcached, depending on value size. On the author’s own site ([www.laruence.com](https://www.laruence.com)) that translated to page renders coming out 19% faster than with the Memcached drop-in. * **Nothing to operate.** No cache server to install, secure, monitor or restart. * **Health you can read.** Hit rate, hits and misses charted over Today / Yesterday/ Last 7 days, with a diagnosis that also says when _not_ to add memory. * **Fails soft.** No extension, or `yac.enable=0`, degrades to a per-request cache and the site keeps serving. **Best fit** Single-node or few-node installs where all PHP workers share a machine. For multi- server clusters needing cross-node consistency, a network cache (Memcached/Redis) suits better. ## Screenshots [⌊Dashboard widget: hit rate, uptime, key slots, values occupied and the 24-hour counters.⌉⌊Dashboard widget: hit rate, uptime, key slots, values occupied and the 24-hour counters.⌉[ Dashboard widget: hit rate, uptime, key slots, values occupied and the 24-hour counters. [⌊Tools → Yac Object Cache: the status bar, with the live shared-memory round trip.⌉⌊ Tools → Yac Object Cache: the status bar, with the live shared-memory round trip .⌉[ Tools Yac Object Cache: the status bar, with the live shared-memory round trip. [⌊Tools → Yac Object Cache: cache status — hit rate, hits and misses over Today / Yesterday / Last 7 days, with the capacity diagnosis on hover.⌉⌊Tools → Yac Object Cache: cache status — hit rate, hits and misses over Today / Yesterday / Last 7 days, with the capacity diagnosis on hover.⌉[ Tools Yac Object Cache: cache status — hit rate, hits and misses over Today / Yesterday/ Last 7 days, with the capacity diagnosis on hover. [⌊Tools → Yac Object Cache: shared memory contents — keys-by-group pie, occupancy totals and the largest (or hottest) entries, each clickable for the entry inspector.⌉⌊ Tools → Yac Object Cache: shared memory contents — keys-by-group pie, occupancy totals and the largest (or hottest) entries, each clickable for the entry inspector .⌉[ Tools Yac Object Cache: shared memory contents — keys-by-group pie, occupancy totals and the largest (or hottest) entries, each clickable for the entry inspector. ## Installation 1. Install the Yac extension, any of three ways (then enable `extension=yac.so` in php.ini): 2. PECL 3. pecl install yac 4. PIE (the PHP Foundation’s PECL successor; yac is on Packagist) 5. pie install laruence/yac Or from source: download the latest [release](https://github.com/laruence/yac/releases), unzip it, then inside: ``` phpize && ./configure && make && make install ``` 1. Install and activate Yac Object Cache. Activation deploys `wp-content/object-cache. php`. That is it — no wp-config edit needed. Visit **Tools Yac Object Cache** to verify status. **Optional php.ini tuning** ``` yac.enable = 1 yac.keys_memory_size = 16M ; ~128K slots (~32K per 4M) yac.values_memory_size = 64M ; raise for large sites (big alloptions) ``` **Optional wp-config switches** ``` define( 'YAC_OCACHE_KEY_PREFIX', 'ab' ); // default wp; give each install its own when sites share one PHP pool define( 'YAC_OCACHE_EMPTY_TTL', 0 ); // default 21600s: lifetime cap on empty negative results; 0 disables define( 'YAC_OCACHE_DISABLE', true ); // escape hatch: force runtime-only mode ``` ## FAQ ### Do I need a Memcached or Redis server? No. That is the point — the cache lives in shared memory on the machine. ### What happens if the Yac extension is not installed? The drop-in degrades to a per-request cache: the site keeps working, you lose cross- request persistence, and the status page flags the missing extension. ### How are keys stored, given Yac’s 48-byte key limit? As `::` (default prefix `wp`), verbatim while they fit the 48-byte budget; over-long keys keep the group verbatim and hash (crc32b) only the key part. ### Does flush() clear other Yac users on the same machine? Yes. `wp_cache_flush()` calls `Yac::flush()`, which wipes the entire shared memory on the machine, including data written by other Yac users sharing the PHP pool. The admin page asks for confirmation first. ### Multisite? Yes. On multisite the Yac instance prefix is `YAC_OCACHE_KEY_PREFIX` + the current blog id (ids up to 9999 verbatim, larger ids a 4-hex crc32b digest), and `switch_to_blog()` re-namespaces: blogs of one install get separate namespaces and never read each other’s entries. The admin page follows the same split — the cache-status totals stay machine-wide, but the shared-memory contents, the group pie and the entry inspector are scoped to (and titled with) the blog you are viewing, so one blog never lists or edits another’s entries. Installs sharing one PHP pool still need different ` YAC_OCACHE_KEY_PREFIX` values. ### What about wp_cache_flush_group()? Yac cannot delete entries by prefix, so a group flush clears the request-level copy of that group; shared entries then expire via TTL. The plugin reports `flush_group` as unsupported so core does not rely on it. ## Reviews ![](https://secure.gravatar.com/avatar/533f3d075bc62d5b1e359f2f3320e96d87bf7503d445c4eb52620b107173d681? s=60&d=retro&r=g) ### 󠀁[Excellent plugin](https://wordpress.org/support/topic/excellent-plugin-9966/)󠁿 [flytomoon](https://profiles.wordpress.org/flytomoon/) شتنبر 13, 2026 Really fast. Switching from my previous cache plugin gave me a 23% QPS boost. [ Read all 1 review ](https://wordpress.org/support/plugin/yac-object-cache/reviews/) ## Contributors & Developers “Yac Object Cache” is open source software. The following people have contributed to this plugin. Contributors * [ laruence ](https://profiles.wordpress.org/laruence/) [Translate “Yac Object Cache” into your language.](https://translate.wordpress.org/projects/wp-plugins/yac-object-cache) ### Interested in development? [Browse the code](https://plugins.trac.wordpress.org/browser/yac-object-cache/), check out the [SVN repository](https://plugins.svn.wordpress.org/yac-object-cache/), or subscribe to the [development log](https://plugins.trac.wordpress.org/log/yac-object-cache/) by [RSS](https://plugins.trac.wordpress.org/log/yac-object-cache/?limit=100&mode=stop_on_copy&format=rss). ## Changelog #### 1.4.0 * Multisite: blogs of one install are now isolated. The Yac instance prefix becomes` YAC_OCACHE_KEY_PREFIX` + the current blog id (ids up to 9999 verbatim, larger ids a 4-hex crc32b digest) and `switch_to_blog()` re-namespaces, so one blog can no longer read another blog’s cached entries (the menu/duplication reports on shared namespaces). Single-site behavior is unchanged; upgrading is a one- time cold start. * Multisite admin: the diagnostics now match that isolation. Cache-status totals stay machine-wide, but shared-memory contents, the group pie and the entry inspector/ delete are scoped to the current blog (the contents heading is titled with the blog name), so a site admin can no longer read or delete another blog’s entries. The flush confirmation now also notes that Yac recycles expired memory on its own, so a manual flush is rarely needed. #### 1.3.1 * Fixed the admin “Remove drop-in” action always reporting failure. * Added WP-CLI commands: `wp yac deploy-dropin`, `wp yac update-dropin`, `wp yac remove-dropin`. * Comment-query cache misses (`WP_Comment_Query::get_comments()` wraps an empty result as `array('comment_ids' => array(), 'found_comments' => 0)`) are now recognized as negative cache results and capped by `YAC_OCACHE_EMPTY_TTL` instead of occupying a slot forever. #### 1.3.0 * No wp-config edit is needed any more: `WP_CACHE` is no longer required or reported. WordPress loads `object-cache.php` regardless of it — that constant only gates` advanced-cache.php` (page caching), which this plugin does not provide. The live CI run now boots WordPress without it to prove the point. * The Cache health panel became a client-side trend chart: hit rate, hits and misses over Today / Yesterday / Last 7 days, with the window’s counters and the capacity diagnosis on hover. Counters are sampled every 15 minutes into a ~7-day ring. * Fixed the entry inspector exhausting the PHP memory limit on a busy cache: it now pages through `Yac::dump()` instead of accumulating the whole dump. * Fixed the dashboard widget reporting “0 bytes” for values occupied. The Active bar now also shows shared-memory uptime. * Suggested tuning raised to `yac.keys_memory_size = 16M` (~128K slots); 4M gives only ~32K. #### 1.2.2 * Fixed stale shared-memory writes: `wp_cache_set()` on a key already written by` wp_cache_add()` in the same request skipped the shared write, so other requests kept reading the value the add stored (the `update_option()` pattern left the old option behind). * Replaced `YAC_OCACHE_SKIP_EMPTY` with `YAC_OCACHE_EMPTY_TTL` (default 21600s): empty results now share as usual but expire instead of occupying a slot forever. * The health panel’s “keys used” reports live entries rather than the `slots_used` high-water mark. #### 1.2.1 * Moved the PHPCS EscapeOutput annotations so WordPress.org Plugin Check recognizes the exemption; annotated `pre_wp_cache_get` as a core hook. #### 1.2.0 * Fixed the health-ring donut disappearing: `wp_kses_post()` strips SVG elements. * Renamed every plugin-owned symbol to the `yac_ocache_`/`YAC_OCACHE_`/`yac-ocache-` prefixes for WordPress.org policy (`wp_` is reserved for core). The `wp_cache_*` functions and `$wp_object_cache` keep their standard names; WP-CLI stays `wp yac status` / `wp yac flush`. #### 1.1.1 * A stored `false` is now written as `0`: Yac’s `get()` returns `false` for both a miss and a stored `false`, so a stored false never survived past the request. * Top entries grew a Hottest tab (by access count) alongside Largest; the entry inspector gained Hits, Embedded-in-slot and `c_len`. * Entry listings page through `Yac::dump()` instead of one `dump(-1)`, which could exhaust the memory limit. #### 1.1.0 * Dashboard rebuilt around a cache-health verdict, keys-by-group pie, largest entries, configuration reference and diagnostics. * Key format rework: `::` with no per-blog prefix; over-long keys hash only the key part. * `YAC_OCACHE_DISABLE` escape hatch forces runtime-only mode. #### 1.0.0 * Initial release. Yac-backed object cache with self-deploying drop-in, verbatim keys with hashed fallback, multisite support, graceful runtime-only fallback, and the admin dashboard. ## Meta * Version **1.4.0** * Last updated **14 ساعة ago** * Active installations **Fewer than 10** * WordPress version ** 5.6 or higher ** * Tested up to **7.1.2** * PHP version ** 7.0 or higher ** * Language * [English (US)](https://wordpress.org/plugins/yac-object-cache/) * Tags * [cache](https://ary.wordpress.org/plugins/tags/cache/)[object cache](https://ary.wordpress.org/plugins/tags/object-cache/) [performance](https://ary.wordpress.org/plugins/tags/performance/) * [Advanced View](https://ary.wordpress.org/plugins/yac-object-cache/advanced/) ## Ratings 5 out of 5 stars. * [ 1 5-star review ](https://wordpress.org/support/plugin/yac-object-cache/reviews/?filter=5) * [ 0 4-star reviews ](https://wordpress.org/support/plugin/yac-object-cache/reviews/?filter=4) * [ 0 3-star reviews ](https://wordpress.org/support/plugin/yac-object-cache/reviews/?filter=3) * [ 0 2-star reviews ](https://wordpress.org/support/plugin/yac-object-cache/reviews/?filter=2) * [ 0 1-star reviews ](https://wordpress.org/support/plugin/yac-object-cache/reviews/?filter=1) [Your review](https://wordpress.org/support/plugin/yac-object-cache/reviews/#new-post) [See all reviews](https://wordpress.org/support/plugin/yac-object-cache/reviews/) ## Contributors * [ laruence ](https://profiles.wordpress.org/laruence/) ## Support Issues resolved in last two months: 1 out of 2 [View support forum](https://wordpress.org/support/plugin/yac-object-cache/)