Over the weekend we became aware of a bug (#33423) in the recently released 4.3 version of WordPress that can cause high CPU load for some sites. A fix for this bug will be included in the first maintenance release, 4.3.1. If you are a GoWP customer your site has already been patched to address this bug in the interim.

In July of 2013 a long-term plan to remove shared taxonomy terms from core was put in place and implementation began with the first of three phases in 4.1. Version 4.3 completed this implementation. However, one of the maintenance functions included in 4.3 contained an error:

/**   * In order to avoid the wp_batch_split_terms() job being accidentally removed,   * check that it's still scheduled while we haven't finished splitting terms.   *   * @ignore   * @since 4.3.0   */  function _wp_check_for_scheduled_split_terms() {          if ( ! get_option( 'finished_splitting_shared_terms' ) && ! wp_next_scheduled( 'wp_batch_split_terms' ) ) {                  wp_schedule_single_event( 'wp_batch_split_terms', time() + MINUTE_IN_SECONDS );          }  }

The arguments passed to wp_schedule_single_event() were reversed, causing invalid entries to the WP Cron system. Thankfully, because of the way this is implemented, not all sites are impacted. Of those that do have these erroneous cronjob entries, very few will have more than a few entries.

Of our customers’ sites, only about 10% were affected at all – and only one severely enough that it interfered with site stability.

A patch for this has been written and will be included in version 4.3.1. We have rolled out a hotfix patch to all GoWP customers’ sites in the meantime.