[rules-users] Delete a List of Facts

[Weiss, Wolfgang]

Hi,

I want to delete a list of facts from the working memory and therefore created following rule:

rule "delete rule"
  agenda-group "evaluation"
  salience 50
  no-loop true

  when
    $facts : ArrayList(size > 0) from collect (Fact())
  then
    logger.info("delete rule, number of facts in list: " + $facts.size());

    for (int i = 0; i < $facts.size(); i++) {
       Fact f = (Fact)$facts.get(i);
       logger.info("retract fact id: " + f.getId());
       retract(f);
    }
end

When inserting 10 facts with IDs 1 to 10 and then fire all rules, I get following result:
delete rule, number of facts in list: 10
retract fact id: 1
retract fact id: 3
retract fact id: 5
retract fact id: 7
retract fact id: 9

but, the facts 2, 4, 6, 8 and 10 are not deleted. I would have expected to set "no-loop" to true, as I do some modification of facts and don't want that this rule is fired again with the same facts. When I set "no-loop" to false, I get following result:
delete rule, number of facts in list: 10
retract fact id: 1
retract fact id: 3
retract fact id: 5
retract fact id: 7
retract fact id: 9
delete rule, number of facts in list: 5
retract fact id: 2
retract fact id: 6
retract fact id: 10
delete rule, number of facts in list: 2
retract fact id: 4
delete rule, number of facts in list: 1
retract fact id: 8

now, all facts are deleted but the "delete rule" was fired 4 times. Is this the intended behavior of Drools? Is there a way to fire a rule only once and delete a list of facts?
I can reproduce this behavior with Drools 5.5.0.Final and 6.0.0.Beta2 but did not try any other version.

Best Regards,
Wolfgang

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