Smarty bus errors
Smarty can show bus errors under load
See
Truncating a compiled template leads to concurrency issues if another process is including the same file. See also CRM-11189 for a description of the "bus error" encountered when one of the concurrent processes dies.
CRM-19013: Compiled templates are truncated CRM-11189: When CiviMail renders smarty templates for mailing, it saves them to disk