When executing the eZ Find updatesearchindexsolr.php script with multiple processes (using --conc=2, for example) , an exception will be thrown:

  [Exception]
  dfs/mysqli DB error: MySQL server has gone away
  SQL Query: SELECT * FROM ezdfsfile_cache WHERE name_hash=MD5('var/ezdemo_site/cache/user-info/1/0/user-data-10.cache.php')

This seems to occur because the cluster DB connection is instantiated before the process forks.

Steps to reproduce:

1. Setup an eZ Publish installation with DFS clustering
2. Install eZ Find and start solr
3. Execute the index update script with multiple processes (default):

   php ezpublish/console ezpublish:legacy:script extension/ezfind/bin/php/updatesearchindexsolr.php --siteaccess=ezdemo_site_admin --conc=2