Debugging drush updb

If you’ve ever tried to debug your update hooks via drush you may (like me) have been puzzled as to why your breakpoints don’t seem to work.

It seems that proc_open() is used to avoid memory issues http://drupal.org/node/687724 (effectively resetting all the Drupal static variables??) and this separate process isn’t available to the debugger.

After stepping though the drush update process I found where this happens and have a bypass that is basically functional (drush reporting seems broken - but I can step through my code).

This patch is the change I’ve made.

I bypass the patch process and go direct to the update.

--- commands/core/drupal/update_6.inc   (revision 547)
+++ commands/core/drupal/update_6.inc   (working copy)
@@ -424,10 +424,7 @@
       'error_message' => 'An unrecoverable error has occurred. You can find the error message below. It is advised to copy it to the clipboard for reference.',
       'finished' => 'update_finished',
     );
-    batch_set($batch);
-    $batch =& batch_get();
-    $batch['progressive'] = FALSE;
-    drush_backend_batch_process('updatedb-batch-process');
+    _update_do_one($module, $version, $batch);
   }
   else {
     drush_log(dt("No database updates required"), 'success');