Asynchronous term object cache clearing for cases when term update times out.

functions.php

<?php

//disable cache invalidation just before the term objects cache is cleared
function my_prefix_deactivate_cache_invalidation( $tt_id, $taxonomy ) {

        //wp_suspend_cache_invalidation returns current status before it get's changed
        $current_cache_suspend_status = wp_suspend_cache_invalidation( true );

        //schedule asynchronous cache clearing
        wp_schedule_single_event( time(), 'my_prefix_invalidate_term_objects_cache', array( $tt_id, $taxonomy ) );

        //if cache invalidation was not previously deactivated, we need to reactivate it
        //neds to check for `true !==` as `wp_suspend_cache_invalidation` returns null in case it was not called previously
        if ( true !==  $current_cache_suspend_status ) {
                add_action( 'edit_term', 'my_prefix_reactivate_cache_invalidation' );
        }
}
add_action( 'edited_term_taxonomy', 'my_prefix_deactivate_cache_invalidation', 10, 2 );

//re-activate cache invalidation
function my_prefix_reactivate_cache_invalidation() {
        wp_suspend_cache_invalidation( false );
}

//Cron triggered function which actually cleans the cache
function my_prefix_invalidate_term_objects_cache( $tt_id, $taxonomy ) {
        global $wpdb;
        $objects = $wpdb->get_col( $wpdb->prepare( "SELECT object_id FROM $wpdb->term_relationships WHERE term_taxonomy_id = %d", $tt_id ) );
        $tax_object = get_taxonomy( $taxonomy );
        foreach ( $tax_object->object_type as $object_type ) {
                clean_object_term_cache( $objects, $object_type );
        }
}
add_action( 'my_prefix_invalidate_term_objects_cache', 'my_prefix_invalidate_term_objects_cache', 10, 2 );

This works only when following patch is in place: https://core.trac.wordpress.org/attachment/ticket/28743/taxonomy.php.patch