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new 143b6ece668 [incubator-kie-drools-6765] Park no-loop/lock-on-active
blocked tuples in dormantMatches (#6768)
143b6ece668 is described below
commit 143b6ece66841c1f88de396e149f4336d15fd147
Author: Toshiya Kobayashi <[email protected]>
AuthorDate: Fri Jun 26 16:27:44 2026 +0900
[incubator-kie-drools-6765] Park no-loop/lock-on-active blocked tuples in
dormantMatches (#6768)
* [incubator-kie-drools-6765] Revisit removeDormantTuple issue
- Test cases
* [incubator-kie-drools-6765] Park no-loop/lock-on-active blocked tuples in
dormantMatches
When doLeftTupleInsert returns early due to no-loop or lock-on-active
guards, the tuple was left as an orphan — not in any RuleExecutor list
but still linked at the join node. A subsequent UPDATE or DELETE would
call removeDormantTuple on the orphan, causing NPE in LinkedList.remove().
Park blocked tuples in dormantMatches before returning, consistent with
the existing activationsFilter path that already parks never-fired tuples
in dormant.
Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>
* temporal change for draft test CI
* Revert "temporal change for draft test CI"
This reverts commit 2183c46ba36978c29020df148a83c0e166efa285.
* comment
* make a comment precise
---------
Co-authored-by: Claude Opus 4.6 (1M context) <[email protected]>
---
.../drools/core/phreak/PhreakRuleTerminalNode.java | 4 +
.../java/org/drools/core/phreak/RuleExecutor.java | 5 +-
.../RemoveDormantTupleNPETest.java | 259 +++++++++++++++++++++
3 files changed, 266 insertions(+), 2 deletions(-)
diff --git
a/drools-core/src/main/java/org/drools/core/phreak/PhreakRuleTerminalNode.java
b/drools-core/src/main/java/org/drools/core/phreak/PhreakRuleTerminalNode.java
index 703f23e7c75..ce75adef6db 100644
---
a/drools-core/src/main/java/org/drools/core/phreak/PhreakRuleTerminalNode.java
+++
b/drools-core/src/main/java/org/drools/core/phreak/PhreakRuleTerminalNode.java
@@ -113,6 +113,7 @@ public class PhreakRuleTerminalNode {
// most recent PropagationContext is required to maintain the right
recency which triggers the match
PropagationContext pctx = leftTuple.findMostRecentPropagationContext();
if ( rtnNode.getRule().isNoLoop() && sameRules(rtnNode,
pctx.getTerminalNodeOrigin()) ) {
+ executor.addDormantTuple(leftTuple);
return;
}
@@ -127,6 +128,7 @@ public class PhreakRuleTerminalNode {
InternalAgendaGroup agendaGroup =
executor.getRuleAgendaItem().getAgendaGroup();
if (blockedByLockOnActive(rtnNode.getRule(), pctx, agendaGroup)) {
activationsManager.getAgendaEventSupport().fireActivationCancelled(leftTuple,
reteEvaluator, MatchCancelledCause.FILTER );
+ executor.addDormantTuple(leftTuple);
return;
}
}
@@ -278,6 +280,8 @@ public class PhreakRuleTerminalNode {
// Expiration propagations should not be removed from the list, as
they still need to fire
executor.removeActiveTuple( leftTuple );
} else if ( leftTuple.getStagedType() == Tuple.DELETE &&
!leftTuple.isQueued() ) {
+ // if Tuple.DELETE, it's not in activeMatches nor dormantMatches.
Basically, unlinked from parent nodes, so will be GC'ed.
+ // Note: there could be a case where such a tuple will be retained
and activated again. (e.g., accPropCtx.getResultLeftTuple())
executor.removeDormantTuple( leftTuple );
}
diff --git a/drools-core/src/main/java/org/drools/core/phreak/RuleExecutor.java
b/drools-core/src/main/java/org/drools/core/phreak/RuleExecutor.java
index 7839ea8813b..46f0de6064b 100644
--- a/drools-core/src/main/java/org/drools/core/phreak/RuleExecutor.java
+++ b/drools-core/src/main/java/org/drools/core/phreak/RuleExecutor.java
@@ -314,7 +314,7 @@ public class RuleExecutor {
if (tuple.getPrevious() != null || dormantMatches.getFirst() == tuple)
{
dormantMatches.remove(tuple);
} else {
- log.debug("Skipping removeDormantTuple for orphan tuple {} on rule
\"{}\" — tuple is not present in dormantMatches",
+ log.warn("Skipping removeDormantTuple for orphan tuple {} on rule
\"{}\" — tuple is not present in dormantMatches",
tuple, ruleAgendaItem.getRule().getName());
}
if (DEBUG_DORMANT_TUPLE) {
@@ -345,7 +345,8 @@ public class RuleExecutor {
activeMatches.remove(tuple);
if (tuple.getStagedType() != Tuple.DELETE) {
addDormantTuple(tuple);
- }
+ } // if Tuple.DELETE, it's not in activeMatches nor dormantMatches.
Basically, unlinked from parent nodes, so will be GC'ed.
+ // Note: there could be a case where such a tuple will be retained
and activated again. (e.g., accPropCtx.getResultLeftTuple())
if (queue != null) {
removeQueuedLeftTuple(tuple);
}
diff --git
a/drools-test-coverage/test-compiler-integration/src/test/java/org/drools/mvel/integrationtests/RemoveDormantTupleNPETest.java
b/drools-test-coverage/test-compiler-integration/src/test/java/org/drools/mvel/integrationtests/RemoveDormantTupleNPETest.java
new file mode 100644
index 00000000000..36c88507b87
--- /dev/null
+++
b/drools-test-coverage/test-compiler-integration/src/test/java/org/drools/mvel/integrationtests/RemoveDormantTupleNPETest.java
@@ -0,0 +1,259 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements. See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership. The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.drools.mvel.integrationtests;
+
+import java.util.stream.Stream;
+
+import org.drools.mvel.compiler.Cheese;
+import org.drools.mvel.compiler.Person;
+import org.drools.testcoverage.common.util.KieBaseTestConfiguration;
+import org.drools.testcoverage.common.util.KieBaseUtil;
+import org.drools.testcoverage.common.util.TestParametersUtil2;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.MethodSource;
+import org.kie.api.KieBase;
+import org.kie.api.runtime.KieSession;
+import org.kie.api.runtime.rule.FactHandle;
+
+/**
+ * Reproducers for NPE in RuleExecutor.removeDormantTuple (issue #6422, PR
#6707).
+ *
+ * Root cause: doLeftTupleInsert can return early (no-loop or lock-on-active
guard)
+ * without adding the tuple to any RuleExecutor list. The tuple remains linked
as
+ * a child at the join node. A subsequent fact modification triggers an UPDATE
for
+ * the orphan, and modifyActiveTuple calls removeDormantTuple on a tuple that
was
+ * never in dormantMatches — NPE in LinkedList.remove().
+ */
+public class RemoveDormantTupleNPETest {
+
+ public static Stream<KieBaseTestConfiguration> parameters() {
+ return
TestParametersUtil2.getKieBaseCloudConfigurations(true).stream();
+ }
+
+ /**
+ * Orphan via no-loop, triggered by external ksession.update().
+ *
+ * R1 (no-loop) fires → inserts new Cheese → new match blocked by no-loop
→ orphan.
+ * External update of Person → UPDATE on orphan → NPE.
+ */
+ @ParameterizedTest(name = "KieBase type={0}")
+ @MethodSource("parameters")
+ public void testNoLoopInsertThenExternalUpdate(KieBaseTestConfiguration
kieBaseTestConfiguration) {
+ final String drl =
+ "package org.drools.reproducer\n" +
+ "import " + Cheese.class.getCanonicalName() + "\n" +
+ "import " + Person.class.getCanonicalName() + "\n" +
+ "\n" +
+ "rule R1\n" +
+ " no-loop true\n" +
+ "when\n" +
+ " $c : Cheese(price > 0)\n" +
+ " $p : Person(age > 0)\n" +
+ "then\n" +
+ " insert(new Cheese(\"inserted\", $c.getPrice() + 100));\n"
+
+ "end\n";
+
+ KieBase kbase = KieBaseUtil.getKieBaseFromKieModuleFromDrl("test",
kieBaseTestConfiguration, drl);
+ KieSession ksession = kbase.newKieSession();
+
+ try {
+ Cheese cheese = new Cheese("original", 1);
+ Person person = new Person("john", 1);
+
+ ksession.insert(cheese);
+ FactHandle personHandle = ksession.insert(person);
+
+ // R1 fires → inserts Cheese("inserted",101) → new match blocked
by no-loop → orphan
+ ksession.fireAllRules();
+
+ // Modify Person externally → right-side UPDATE at R1's join node
hits the orphan
+ person.setAge(2);
+ ksession.update(personHandle, person);
+
+ // doLeftTupleUpdate → modifyActiveTuple → removeDormantTuple → NPE
+ ksession.fireAllRules();
+ } finally {
+ ksession.dispose();
+ }
+ }
+
+ /**
+ * Orphan via no-loop, triggered by a second rule's modify — single
fireAllRules.
+ *
+ * R1 (no-loop, higher salience) fires first → inserts new Cheese → orphan.
+ * R2 fires second → modifies Person → UPDATE on orphan → NPE.
+ * All within one fireAllRules() call.
+ */
+ @ParameterizedTest(name = "KieBase type={0}")
+ @MethodSource("parameters")
+ public void testNoLoopCrossRuleModify(KieBaseTestConfiguration
kieBaseTestConfiguration) {
+ final String drl =
+ "package org.drools.reproducer\n" +
+ "import " + Cheese.class.getCanonicalName() + "\n" +
+ "import " + Person.class.getCanonicalName() + "\n" +
+ "\n" +
+ "rule R1\n" +
+ " no-loop true\n" +
+ " salience 10\n" +
+ "when\n" +
+ " $c : Cheese(price > 0)\n" +
+ " $p : Person(age > 0)\n" +
+ "then\n" +
+ " insert(new Cheese(\"inserted\", $c.getPrice() + 100));\n"
+
+ "end\n" +
+ "\n" +
+ "rule R2\n" +
+ " no-loop true\n" +
+ " salience 5\n" +
+ "when\n" +
+ " $c : Cheese(type == \"original\")\n" +
+ " $p : Person(age > 0)\n" +
+ "then\n" +
+ " modify($p) { setAge($p.getAge() + 1) };\n" +
+ "end\n";
+
+ KieBase kbase = KieBaseUtil.getKieBaseFromKieModuleFromDrl("test",
kieBaseTestConfiguration, drl);
+ KieSession ksession = kbase.newKieSession();
+
+ try {
+ ksession.insert(new Cheese("original", 1));
+ ksession.insert(new Person("john", 1));
+
+ // R1 fires (salience 10): inserts Cheese("inserted",101) → orphan
at R1's terminal.
+ // R2 fires (salience 5): modifies Person → right-side UPDATE at
R1's join node.
+ // R1 re-evaluates: doLeftTupleUpdate on orphan →
modifyActiveTuple → NPE.
+ ksession.fireAllRules();
+ } finally {
+ ksession.dispose();
+ }
+ }
+
+ /**
+ * Orphan via lock-on-active, triggered by external ksession.update().
+ *
+ * R1 (lock-on-active, agenda-group) fires → inserts new Cheese → new match
+ * blocked by lock-on-active → orphan.
+ * After the group deactivates, external update of Person + re-focus → NPE.
+ */
+ @ParameterizedTest(name = "KieBase type={0}")
+ @MethodSource("parameters")
+ public void
testLockOnActiveInsertThenExternalUpdate(KieBaseTestConfiguration
kieBaseTestConfiguration) {
+ final String drl =
+ "package org.drools.reproducer\n" +
+ "import " + Cheese.class.getCanonicalName() + "\n" +
+ "import " + Person.class.getCanonicalName() + "\n" +
+ "\n" +
+ "rule R1\n" +
+ " agenda-group \"group1\"\n" +
+ " lock-on-active true\n" +
+ "when\n" +
+ " $c : Cheese(price > 0)\n" +
+ " $p : Person(age > 0)\n" +
+ "then\n" +
+ " insert(new Cheese(\"inserted\", $c.getPrice() + 100));\n"
+
+ "end\n";
+
+ KieBase kbase = KieBaseUtil.getKieBaseFromKieModuleFromDrl("test",
kieBaseTestConfiguration, drl);
+ KieSession ksession = kbase.newKieSession();
+
+ try {
+ Cheese cheese = new Cheese("original", 1);
+ Person person = new Person("john", 1);
+
+ ksession.insert(cheese);
+ FactHandle personHandle = ksession.insert(person);
+
+ // Activate group and fire. R1 fires → inserts
Cheese("inserted",101).
+ // New match blocked by lock-on-active → orphan.
+ ksession.getAgenda().getAgendaGroup("group1").setFocus();
+ ksession.fireAllRules();
+
+ // Modify Person while group is inactive (update recency <
activation recency
+ // when group is re-focused, so lock-on-active won't block the
update).
+ person.setAge(2);
+ ksession.update(personHandle, person);
+
+ // Re-focus and fire. doLeftTupleUpdate processes the UPDATE on
the orphan.
+ // lock-on-active check passes (fact was modified before group
re-activation).
+ // modifyActiveTuple → removeDormantTuple → NPE.
+ ksession.getAgenda().getAgendaGroup("group1").setFocus();
+ ksession.fireAllRules();
+ } finally {
+ ksession.dispose();
+ }
+ }
+
+ /**
+ * Orphan via no-loop, triggered by DELETE (retract) — single fireAllRules,
+ * no external update, no modify.
+ *
+ * R1 (no-loop) fires → inserts a new fact → new match blocked by no-loop
→ orphan.
+ * R2 retracts the inserted fact → LEFT DELETE propagates to orphan →
+ * doLeftDelete → removeDormantTuple → NPE.
+ *
+ * This is the most realistic scenario: rules only use insert/retract (no
modify),
+ * and the NPE occurs within a single fireAllRules() call.
+ */
+ @ParameterizedTest(name = "KieBase type={0}")
+ @MethodSource("parameters")
+ public void
testNoLoopInsertRetractNoExternalUpdate(KieBaseTestConfiguration
kieBaseTestConfiguration) {
+ // R1: inserts a new Cheese("big", price+100) when it finds a cheap
Cheese with a Person.
+ // The new Cheese re-matches R1 with the same Person → blocked by
no-loop → orphan.
+ //
+ // R2: retracts any Cheese with price > 50. This covers the inserted
Cheese("big", 101).
+ // Retracting it propagates a LEFT DELETE through R1's join node,
hitting the orphan.
+ final String drl =
+ "package org.drools.reproducer\n" +
+ "import " + Cheese.class.getCanonicalName() + "\n" +
+ "import " + Person.class.getCanonicalName() + "\n" +
+ "\n" +
+ "rule R1\n" +
+ " no-loop true\n" +
+ " salience 10\n" +
+ "when\n" +
+ " $c : Cheese(price > 0)\n" +
+ " $p : Person(age > 0)\n" +
+ "then\n" +
+ " insert(new Cheese(\"big\", $c.getPrice() + 100));\n" +
+ "end\n" +
+ "\n" +
+ "rule R2\n" +
+ " salience 1\n" +
+ "when\n" +
+ " $c : Cheese(price > 50)\n" +
+ "then\n" +
+ " retract($c);\n" +
+ "end\n";
+
+ KieBase kbase = KieBaseUtil.getKieBaseFromKieModuleFromDrl("test",
kieBaseTestConfiguration, drl);
+ KieSession ksession = kbase.newKieSession();
+
+ try {
+ ksession.insert(new Cheese("original", 1));
+ ksession.insert(new Person("john", 1));
+
+ // R1 fires (salience 10): inserts Cheese("big",101) → orphan at
R1's terminal.
+ // R2 fires (salience 1): retracts Cheese("big",101) → LEFT DELETE
on orphan.
+ // doLeftDelete → removeDormantTuple on orphan → NPE.
+ ksession.fireAllRules();
+ } finally {
+ ksession.dispose();
+ }
+ }
+}
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