Questions about Triggers of Rules

Hi there,

I am running Openhab on an RPI 4,

I am trying to set up some advanced rules with multiple triggers.

To be honest i understand how to write rules, but not what is under the hood.

Are there any potential downsides in having “many” rules with a lot of triggers?
Lets say a rule looks like this and i have like 30 of them.

rule "Test"
    Item Something1  changed or 
    Item Something2  changed or
    Item Something3  changed or 
    Item Something4  changed or
    Item Something5  changed or
    Item Something6  changed or 
    Item Something7  changed or
    Item Something8  changed or 
    Item Something9  changed or
    Item Something10 changed or
    Item Something11 changed or
    Item Something12 changed or
    Item Something13 changed or 
    Item Something14 changed or
    Item Something15 changed or
    Item Something16 changed or 
    Item Something17 changed or
    Item Something18 changed or 
    Item Something19 changed or
  do some stuff based on other stuff

Would be nice to know before i put a lot of work in them :wink:


That works, or you could put all these Items into a Group Item and then you have a single trigger on a Group Member change…


The negative side of this is - if all these items change within a millisecond of each other, the rule will run multiple times.

As mentioned above, better off doing a group with those items with a timer inside the rule so if the timer exists (meaning it’s running), not to run the rule again if another item changes in the group when its running.

Best, Jay

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Thanks for the input with the group. :slight_smile: I will do that

About the timer: I wannt all the items as trigger beacuse each of them is important. If i doo the timer thing and 2 items change very fast in series both changes could be important but i could miss the later one… right?


Correct, if the rule has lots of logic based on what specific item changed, then Yes you would miss sometime with a timer.

Best, Jay

thanks again :slight_smile:

It is usually possible to code carefully to avoid that, using variables derived solely from the triggering event, and none from “current state” (which as you suggest, might change after triggering): Depends exactly what is done.

Everything mentioned so far is correct but I wanted to provide some additional info.

  1. As mentioned, it’s probably best to use a Group with a Member of trigger for ease of flexibility and to make writing the rule easier. If you need to know the Item that triggered the rule there is the implicit variable triggeringItem which is a reference to the Item that triggered the rule.

  2. Even if you list each Item individually you’ll have access to the triggeringItemName to know which Item triggered the rule.

  3. In OH 3 only one instance of the rule can run at a time. So if the rule is running and then gets triggered again, that second trigger will be queued and not run until the previously triggered rule completes. Therefore, especially with a rule that has lots of triggers, you can’t always rely on it running immediately when that trigger is received.

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thanks for the Info