Check_MK Werk 4427: Fixed temporal spreading of pnp4nagios' XML file updates.

ID: 4427 Title: Fixed temporal spreading of pnp4nagios' XML file updates. Component: Core & setup Level: 1 Class: Bug fix Version: 1.5.0i1 If you use the old pnp4nagios format with one metric per RRD, the core needs to create/update an XML description for each RRD from time to time. To avoid creation/update storms after e.g. reloads or mass imports of new hosts, this work should be spread over several (currently 10) minutes. Due to a bug this spreading didn't work, which has been fixed.