Exception in Workflow with active error logging

If a scheduled workflow has many records (more than 1500,in my case), an exception ocures, because there is no more filepointer available (1024 fp limited in my system).

This is the error message: The exception occurred while attempting to log: Entering Users() method ...) ...[CRON]Continue in process exception {module:ProjectTask, id:367886 } err: (The stream or file "/usr/www/users/xxxx/logs/vtigercrm.log" could not be opened in append mode:

The reason is that each Logger::getLogger(...) consumes one fp, but this is never released)