[rules-users] Memory Leak in 5.4.0 and 5.5.0 [was: Garbage collection and sliding windows (Drools 5.5.0 Final)]
Wolfgang Laun
wolfgang.laun at gmail.com
Sun Feb 17 03:55:21 EST 2013
With Drools 5.4.0.Final and 5.5.0.Final, automatic event retraction in
combination with a sliding window is broken, i.e., it suffers from a
memory leak. Full code for a demo has been posted by tai-atari; so I
just add some diagnostics that clearly indicate what goes wrong.
In the snapshot taken with jmap -histo:live after running the program
for several seconds and the insertion of 15800 AnEvent facts you can
see:
* several classes with 2000 instances each - AnEvents and the ones
required for bookkeeping the future expiry
* EventFactHandle, WindowTupleList, ObjectHashMap$ObjectEntry all
growing without restraint, indicating a memory leak.
num #instances #bytes class name
----------------------------------------------
1: 8747 8696096 [S
2: 26985 4110776 <constMethodKlass>
3: 26985 2161888 <methodKlass>
4: 47816 2046304 <symbolKlass>
5: 2414 1482672 <constantPoolKlass>
6: 6142 1434280 [I
7: 13800 1324800 org.drools.common.EventFactHandle
8: 2414 1056424 <instanceKlassKlass>
9: 1891 854664 <constantPoolCacheKlass>
10: 8348 644704 [C
11: 13800 441600 org.drools.reteoo.WindowTupleList
12: 2571 426976 [B
13: 15800 379200
org.drools.core.util.ObjectHashMap$ObjectEntry
14: 2672 256512 java.lang.Class
15: 545 246776 <methodDataKlass>
16: 7852 188448 java.lang.String
17: 4084 185496 [[I
18: 2000 176000 org.drools.common.PropagationContextImpl
19: 8 164288 [Lorg.drools.core.util.Entry;
20: 2000 160000 org.drools.common.AgendaItem
21: 2005 128320 org.drools.reteoo.WindowTuple
22: 2000 128000 org.drools.reteoo.RuleTerminalNodeLeftTuple
23: 2001 96048 java.util.concurrent.FutureTask$Sync
24: 2001 80040
java.util.concurrent.ScheduledThreadPoolExecutor$ScheduledFutureTask
25: 1165 79152 [J
26: 229 75112 <objArrayKlassKlass>
27: 2001 64032
org.drools.time.impl.JDKTimerService$JDKJobHandle
28: 2001 64032 org.drools.time.impl.DefaultTimerJobInstance
29: 423 54728 [Ljava.lang.Object;
30: 2150 51600 java.util.LinkedList$Entry
31: 2052 49248 java.util.LinkedList
32: 2002 48048
org.drools.core.util.ObjectHashSet$ObjectEntry
33: 2001 48024 java.util.Date
34: 2000 48000
org.drools.reteoo.ObjectTypeNode$ExpireJobContext
35: 1958 46992 java.util.HashMap$Entry
36: 2261 36176 java.lang.Integer
37: 2006 32096 java.util.concurrent.atomic.AtomicBoolean
38: 2001 32016 org.drools.time.impl.PointInTimeTrigger
39: 2000 32000
org.drools.reteoo.ReteooWorkingMemory$WorkingMemoryReteExpireAction
40: 2000 32000 memcons.AnEvent
On 17/02/2013, tai-atari <p00temkin at gmail.com> wrote:
> Hi laune,
>
> Really appreciate you trying to reproduce the issue. Since you are not
> experiencing the same behavior I'm obviously missing something. I've
> attached a very simple example below which reproduces the scenario for the
> Drools versions I have tried so far: 5.2, 5.4 and 5.5.
>
> Basically this example runs an infinite loop which inserts 200 events about
> every second, and keeps a sliding window of 10 seconds. Every loop will
> print the current wm event count, which will increase to 2000 and stay put.
> This is where I expected the expired events to be available for garbage
> collection (since only 2000 are concurrently active in wm). But VisualVM
> shows that org.drools.common.EventFactHandle uses an increasing amount of
> memory over time.
>
> Start.java:
> ==================================
> package org.drools.example;
>
> import java.util.Random;
>
> import org.drools.KnowledgeBase;
> import org.drools.KnowledgeBaseConfiguration;
> import org.drools.KnowledgeBaseFactory;
> import org.drools.builder.KnowledgeBuilder;
> import org.drools.builder.KnowledgeBuilderError;
> import org.drools.builder.KnowledgeBuilderErrors;
> import org.drools.builder.KnowledgeBuilderFactory;
> import org.drools.builder.ResourceType;
> import org.drools.conf.EventProcessingOption;
> import org.drools.io.ResourceFactory;
> import org.drools.runtime.StatefulKnowledgeSession;
> import org.drools.runtime.rule.WorkingMemoryEntryPoint;
>
> public class Start {
>
> public static final void main(String[] args) {
> try {
>
> System.out.println("Init");
> KnowledgeBase kbase = readKnowledgeBase();
> StatefulKnowledgeSession ksession =
> kbase.newStatefulKnowledgeSession();
> WorkingMemoryEntryPoint eventStream =
> ksession.getWorkingMemoryEntryPoint("TheEventStream");
> Random randGen = new Random();
>
> while( true ) {
>
> // Insert 200
> int x = 0;
> while( x < 200 ) {
> AnEvent anEvent = new AnEvent();
> anEvent.setSource(randGen.nextInt());
> eventStream.insert(anEvent);
> ksession.fireAllRules();
> x++;
> }
>
> System.out.println("current event count in wm" + ": " +
> eventStream.getFactCount());
> Thread.sleep(1000);
> }
>
> //ksession.dispose();
>
> } catch (Throwable t) {
> t.printStackTrace();
> }
> }
>
> private static KnowledgeBase readKnowledgeBase() throws Exception {
>
> KnowledgeBuilder kbuilder =
> KnowledgeBuilderFactory.newKnowledgeBuilder();
> kbuilder.add(ResourceFactory.newClassPathResource("Sample.drl"),
> ResourceType.DRL);
> KnowledgeBuilderErrors errors = kbuilder.getErrors();
> if (errors.size() > 0) {
> for (KnowledgeBuilderError error: errors) {
> System.err.println(error);
> }
> throw new IllegalArgumentException("Could not parse
> knowledge.");
> }
>
> final KnowledgeBaseConfiguration kbConfig =
> KnowledgeBaseFactory.newKnowledgeBaseConfiguration();
> kbConfig.setOption(EventProcessingOption.STREAM);
> KnowledgeBase kbase = KnowledgeBaseFactory.newKnowledgeBase(kbConfig);
>
> kbase.addKnowledgePackages(kbuilder.getKnowledgePackages());
> return kbase;
> }
>
> }
> ==================================
>
> AnEvent.java:
> ==================================
> package org.drools.example;
>
> public class AnEvent {
>
> private Integer source;
>
> public AnEvent () {
> }
>
> public Integer getSource() {
> return source;
> }
>
> public void setSource(Integer source) {
> this.source = source;
> }
>
> }
> ==================================
>
> Sample.drl
> ==================================
> package org.drools.example
> import org.drools.example.AnEvent;
>
> declare AnEvent
> @role( event )
> end
>
> rule "Event print"
> when
> AnEvent ( $src: source ) over window:time(10s) from entry-point
> TheEventStream
> then
> System.out.println("---------> Received AnEvent from " + $src);
> end
> ==================================
>
> Also tried using an immutable pojo as you suggested cusmaimatteo, with
>
> AnEvent.java:
> ==================================
> package org.drools.example;
>
> public class AnEvent {
>
> private final Integer source;
>
> public AnEvent (Integer i) {
> this.source = i;
> }
>
> public Integer getSource() {
> return source;
> }
> }
> ==================================
>
> and using instead using
>
> eventStream.insert(new AnEvent(randGen.nextInt()));
>
> but with the same memory issues noted.
>
>
>
>
>
> --
> View this message in context:
> http://drools.46999.n3.nabble.com/Garbage-collection-and-sliding-windows-Drools-5-5-0-Final-tp4022183p4022350.html
> Sent from the Drools: User forum mailing list archive at Nabble.com.
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