Ack'd and queued.
On 07/22/2014 11:46 PM, Kent Anderson wrote:
It appears there is another condition where Drools holds onto memory
indefinitely. (See https://issues.jboss.org/browse/DROOLS-516)
Use case: We have a set of rules designed to detect a heartbeat, then
report when/if the heartbeat stops.
Problem: In the normal case of a constant heartbeat, memory is
retained in the JVM, even though the fact count in working memory is 1.
The following rules produce this problem. I have attached a test
project that demonstrates this problem. 600K events are inserted into
the stream, then the test driver waits. After 10 seconds, the
absence detected rule fires. Requesting a GC via JMC has no effect.
If you hit a key while the test driver is waiting, a new event will
be added, which will cause the clear absence alarm rule to fire. At
this point some memory is freed automatically. Requesting another GC
removes all memory and the JVM is back in its (nearly) new condition.
We consider this a memory leak since the events are gone from working
memory and will no longer be considered in any rule evaluations, but
they are still active somewhere in the JVM.
packageorg.drools.example.api.kiemodulemodel
import demo.Event
declareEvent
@role( event )
@timestamp( timestamp )
end
declare Heartbeat
@role( event )
@timestamp( event.timestamp )
event : Event
end
declare AbsenceDetected
name: String
end
/*
* This rule matches the first event
*
* NOTE: This stream requires the heartbeat event
* to occur at least once before absence will be detected.
*/
ruledetect first heartbeat
when
$event : Event()
not ( Heartbeat() )
then
delete($event);
insert(new Heartbeat($event));
System.out.println([DFH] Got event: + $event.getEventId());
end
/*
* This rule matches every event and stores only the most recent
* as the heartbeat.
*/
rulekeep latest heartbeat
when
$heartbeat : Heartbeat()
$event : Event()
then
delete($heartbeat);
insert(new Heartbeat($event));
System.out.println([KLH] Got event: + $event.getEventId());
delete($event);
end
/*
* This rule detects when a heartbeat stops for 10s
*/
ruledetect absence
duration(10s)
when
$heartbeat : Heartbeat()
not ( Event() )
not (AbsenceDetected() )
then
delete($heartbeat);
insert(new AbsenceDetected(Absence));
System.out.println([DA] Absence detected);
end
/*
* This rule detects when the heartbeat starts again after
* absence has been detected.
*/
ruleclear absence alarm
when
$heartbeat : Heartbeat()
$absence : AbsenceDetected ()
then
delete($absence);
System.out.println([CAA] Heartbeat restored);
end
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