[wp-trac] [WordPress Trac] #35454: `lazyload_term_meta` is called many time when calling `get_term_metadata`

[WordPress Trac]

#35454: `lazyload_term_meta` is called many time when calling `get_term_metadata`
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 Reporter:  sfai05        |       Owner:
     Type:  defect (bug)  |      Status:  new
 Priority:  normal        |   Milestone:  Awaiting Review
Component:  General       |     Version:  4.4
 Severity:  normal        |  Resolution:
 Keywords:                |     Focuses:  performance
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Comment (by boonebgorges):

 @sfai05 - Thanks for the details.

 I'm struggling to see whether this is a fundamental architectural problem
 with the lazyloading technique, or whether there's a race condition that's
 causing many more cache checks than is required. Maybe you can help me
 figure this out.

 `WP_Query::lazyload_term_meta()` is designed to bail when
 `$this->updated_term_meta_cache` is true. However, this flag doesn't get
 set until the end of the method. I wonder if this fact, combined with lots
 of calls to `get_term_meta()`, is causing `get_object_term_cache()` to be
 called more often than it should. Two things to look at:

 * How many times is `lazyload_term_meta()` being called? (It should be
 once for every call to `get_term_meta()`.) And how many times is it
 getting past the `$this->update_term_meta_cache` flag? (It should be once
 for each `WP_Query` loop previously loaded on the page.)
 * If you move the `$this->updated_term_meta_cache = true` check to the top
 of the method - just before the `// We can only lazyload...` comment -
 does it help?

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Ticket URL: <https://core.trac.wordpress.org/ticket/35454#comment:3>
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