Steps to reproduce:

Create LLD discovery with some item having multiple tags of the same name and different values (i.e. Application = App1, Application = App2)

 

Result:

It seems multiple tag values are processed in random order during RRD, and so Zabbix generates a lot of audit events on every discovery showing it changes discovered item tags from one value to other value set back and forth each discovery.

I.e.

{{

{"item.tag[472542]":["update"],"item.tag[472542].value":["update","Port traffic","Ports"],"item.tag[472584]":["update"],"item.tag[472584].value":["update","Ports","Port traffic"]}

}}

You can clearly see it just changed the value order

All item tags are applied correctly to discovered items though, there is just a HUGE bloat of audit messages.

Probably database operations to change tag values are performed as well.

 

Expected:

Existing tag values are not causing any excessive changes on discovered items during LLD. New tag values are added, removed are removed.

 

Resolution considerations:

Not sure if this happens on trigger tags with LLD as well.

The simple but quirky fix can probably be done easy just by sorting tag value sets before applying. It will still change multiple tags when tag value count changes.

More proper fix should compare possible values of the tag and only delete what's removed and add what's added.