INF arriving via node_cron_comments_scale derails search

Drupal goes into the weeds on occasion, with no obvious trigger, and — once it gets into this state — every search fails.

The proximate trigger is a search (for anything), and once one goes wrong all of which fail with the cited red box error.

The error in the red box is always the 'INF' string embedded in the SELECT query.

Sometimes purging the search database and reloading it via cron seems to cure the problem.

cron is run manually at present.

Something upstream is loading the $scale variable with 'INF'.

This really smells like an uninitialized variable somewhere, or a version-level difference in what gets returned.

(If I could provide a reproducer, I would have done so. I have found that the specified hack seems to have cured the most recent round of problems. I'd love to cite chapter and verse and reproducer — was that available, the fix would have been queued. I'm just sorting out the internals of Drupal.)

The bug has hit earlier and on multiple occasions, and I've recently had the cycles to dig into it. Here's the earlier report 78102.

Division by zero? It may well be, but that is well upstream of this section of code somewhere, and probably around the calculation of or the assignment of the node_cron_comments_scale variable.

This particular php code clearly constructs part of the search select query, and the specific $scale looks to multiply by floating zero, which obviously clobbers the factor.

Having it floating zeroed out bothers me far less than having the 'INF' string embedded in the query in the position of the , as having 'INF' in the query derails the entire search. To wit: (2.0 - 2.0 / (1.0 + nc.totalcount * -INF)) This implies the INF string (negative INF, in this case) is arriving via $scale, which back-tracks pretty quickly to the node_cron_comments_scale variable. I haven't back-tracked what code assigns that value.

The assignment overwrites the 'INF' that is occasionally arriving in the query.

As for the search weights, the values for Keyword relevance, Recently posted, Number of comments, Number of views are each set to 5.

Here's a fix — some might use reasonably “workaround” here — for use within node.module. This code adds a pair of is_infinite checks into the sequence, and suppresses the errors. This has been in production use for over a month now with Drupal 5.1 and replicated into the local 5.2 within a couple of days of that release, with no untoward effects and with no re-occurrences of the original INF errors. This code is also now operating on PHP 5.2.2, as well, though should operate on the original PHP.

      if (module_exists('comment') && $weight = (int)variable_get('node_rank_comments', 5)) {
        // Inverse law that maps the highest reply count on the site to 1 and 0 to 0.
        $scale = variable_get('node_cron_comments_scale', 0.0);
        if (is_infinite($scale))
          $scale = 0.0;
        $ranking[] = '%d * (2.0 - 2.0 / (1.0 + c.comment_count * %f))';

…and a little further along…

      if (module_exists('statistics') && variable_get('statistics_count_content_views', 0) &&
          $weight = (int)variable_get('node_rank_views', 5)) {
        // Inverse law that maps the highest view count on the site to 1 and 0 to 0.
        $scale = variable_get('node_cron_views_scale', 0.0);        
        if (is_infinite($scale)) 
          $scale = 0.0;
        $ranking[] = '%d * (2.0 - 2.0 / (1.0 + nc.totalcount * %f))';

Current versions:

• Drupal 5.2
• Apache/1.3.33 (Darwin) PHP/5.2.2 mod_jk/1.2.6 DAV/1.0.3 mod_ssl/2.8.24 OpenSSL/0.9.7l mod_perl/1.29
• MySQL 4.1.22