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Merged
merged 6 commits into from
Aug 25, 2025
Merged

Add not-preferred allocation decision #133177

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1dbdc7b
single dimension type
mhl-b Aug 23, 2025
5a0f1b4
test fix
mhl-b Aug 23, 2025
933632d
Merge remote-tracking branch 'upstream/main' into decision-not-preferred
mhl-b Aug 25, 2025
2e0c8fa
add todo
mhl-b Aug 25, 2025
2ac0ec0
test fix
mhl-b Aug 25, 2025
3473090
Merge remote-tracking branch 'upstream/main' into decision-not-preferred
mhl-b Aug 25, 2025
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1 change: 1 addition & 0 deletions server/src/main/java/org/elasticsearch/TransportVersions.java
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Original file line number Diff line number Diff line change
Expand Up @@ -368,6 +368,7 @@ static TransportVersion def(int id) {
public static final TransportVersion DATA_STREAM_WRITE_INDEX_ONLY_SETTINGS = def(9_142_0_00);
public static final TransportVersion SCRIPT_RESCORER = def(9_143_0_00);
public static final TransportVersion ESQL_LOOKUP_OPERATOR_EMITTED_ROWS = def(9_144_0_00);
public static final TransportVersion ALLOCATION_DECISION_NOT_PREFERRED = def(9_145_0_00);

/*
* STOP! READ THIS FIRST! No, really,
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2 changes: 1 addition & 1 deletion server/src/main/java/org/elasticsearch/cluster/routing/allocation/AllocationDecision.java
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Expand Up @@ -111,7 +111,7 @@ public static AllocationDecision fromAllocationStatus(AllocationStatus allocatio
*/
public static AllocationDecision fromDecisionType(Decision.Type type) {
return switch (type) {
case YES -> YES;
case YES, NOT_PREFERRED -> YES;
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I think we should add a todo here, preferably with a JIRA number attached. We need to figure out what to do. Perfectly fine to defer.

case THROTTLE -> THROTTLED;
case NO -> NO;
};
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2 changes: 1 addition & 1 deletion server/src/main/java/org/elasticsearch/cluster/routing/allocation/MoveDecision.java
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Expand Up @@ -232,7 +232,7 @@ public String getExplanation() {
? Explanations.Rebalance.CANNOT_REBALANCE_CAN_ALLOCATE
: Explanations.Rebalance.CANNOT_REBALANCE_CANNOT_ALLOCATE;
case THROTTLE -> Explanations.Rebalance.CLUSTER_THROTTLE;
case YES -> {
case YES, NOT_PREFERRED -> {
if (getTargetNode() != null) {
yield canMoveDecision == AllocationDecision.THROTTLED
? Explanations.Rebalance.NODE_THROTTLE
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23 changes: 12 additions & 11 deletions ...rc/main/java/org/elasticsearch/cluster/routing/allocation/decider/AllocationDeciders.java
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Expand Up @@ -205,31 +205,32 @@ private Decision withDeciders(
BiFunction<String, Decision, String> logMessageCreator
) {
if (debugMode == RoutingAllocation.DebugMode.OFF) {
Decision result = Decision.YES;
Decision mostNegativeDecision = Decision.YES;
for (AllocationDecider decider : deciders) {
var decision = deciderAction.apply(decider);
if (decision.type() == Decision.Type.NO) {
if (logger.isTraceEnabled()) {
logger.trace(() -> logMessageCreator.apply(decider.getClass().getSimpleName(), decision));
if (mostNegativeDecision.type().higherThan(decision.type())) {
mostNegativeDecision = decision;
if (mostNegativeDecision.type() == Decision.Type.NO) {
if (logger.isTraceEnabled()) {
logger.trace(() -> logMessageCreator.apply(decider.getClass().getSimpleName(), decision));
}
break;
}
return decision;
} else if (result.type() == Decision.Type.YES && decision.type() == Decision.Type.THROTTLE) {
result = decision;
}
}
return result;
return mostNegativeDecision;
} else {
var result = new Decision.Multi();
final var multiDecision = new Decision.Multi();
for (AllocationDecider decider : deciders) {
var decision = deciderAction.apply(decider);
if (logger.isTraceEnabled() && decision.type() == Decision.Type.NO) {
logger.trace(() -> logMessageCreator.apply(decider.getClass().getSimpleName(), decision));
}
if (decision != Decision.ALWAYS && (debugMode == RoutingAllocation.DebugMode.ON || decision.type() != Decision.Type.YES)) {
result.add(decision);
multiDecision.add(decision);
}
}
return result;
return multiDecision;
}
}

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77 changes: 41 additions & 36 deletions server/src/main/java/org/elasticsearch/cluster/routing/allocation/decider/Decision.java
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Expand Up @@ -9,6 +9,7 @@

package org.elasticsearch.cluster.routing.allocation.decider;

import org.elasticsearch.TransportVersions;
import org.elasticsearch.common.io.stream.StreamInput;
import org.elasticsearch.common.io.stream.StreamOutput;
import org.elasticsearch.common.io.stream.Writeable;
Expand All @@ -33,6 +34,7 @@ public sealed interface Decision extends ToXContent, Writeable permits Decision.

Single ALWAYS = new Single(Type.YES);
Single YES = new Single(Type.YES);
Single NOT_PREFERRED = new Single(Type.NOT_PREFERRED);
Single NO = new Single(Type.NO);
Single THROTTLE = new Single(Type.THROTTLE);

Expand Down Expand Up @@ -72,6 +74,7 @@ private static Single readSingleFrom(StreamInput in) throws IOException {
if (label == null && explanation == null) {
return switch (type) {
case YES -> YES;
case NOT_PREFERRED -> NOT_PREFERRED;
case THROTTLE -> THROTTLE;
case NO -> NO;
};
Expand Down Expand Up @@ -103,48 +106,58 @@ private static Single readSingleFrom(StreamInput in) throws IOException {
List<Decision> getDecisions();

/**
* This enumeration defines the
* possible types of decisions
* This enumeration defines the possible types of decisions
*/
enum Type implements Writeable {
YES(1),
THROTTLE(2),
NO(0);
// ordered by positiveness; order matters for serialization and comparison
NO,
THROTTLE,
NOT_PREFERRED,
YES;

private final int id;

Type(int id) {
this.id = id;
public static Type readFrom(StreamInput in) throws IOException {
if (in.getTransportVersion().onOrAfter(TransportVersions.ALLOCATION_DECISION_NOT_PREFERRED)) {
return in.readEnum(Type.class);
} else {
int i = in.readVInt();
return switch (i) {
case 0 -> NO;
case 1 -> YES;
case 2 -> THROTTLE;
default -> throw new IllegalArgumentException("No Type for integer [" + i + "]");
};
}
}

public static Type readFrom(StreamInput in) throws IOException {
int i = in.readVInt();
return switch (i) {
case 0 -> NO;
case 1 -> YES;
case 2 -> THROTTLE;
default -> throw new IllegalArgumentException("No Type for integer [" + i + "]");
};
/**
* @return lowest decision by natural order
*/
public static Type min(Type a, Type b) {
return a.compareTo(b) < 0 ? a : b;
}

@Override
public void writeTo(StreamOutput out) throws IOException {
out.writeVInt(id);
if (out.getTransportVersion().onOrAfter(TransportVersions.ALLOCATION_DECISION_NOT_PREFERRED)) {
out.writeEnum(this);
} else {
out.writeVInt(switch (this) {
case NO -> 0;
case NOT_PREFERRED, YES -> 1;
case THROTTLE -> 2;
});
}
}

public boolean higherThan(Type other) {
if (this == NO) {
return false;
} else if (other == NO) {
return true;
} else return other == THROTTLE && this == YES;
return this.compareTo(other) > 0;
}

/**
* @return lowest decision by precedence NO->THROTTLE->YES
* @return true if Type is one of {NOT_PREFERRED, YES}
*/
public static Type min(Type a, Type b) {
return a.higherThan(b) ? b : a;
public boolean allowed() {
return this.compareTo(NOT_PREFERRED) >= 0;
}

}
Expand Down Expand Up @@ -243,16 +256,8 @@ public Multi add(Decision decision) {

@Override
public Type type() {
Type ret = Type.YES;
for (int i = 0; i < decisions.size(); i++) {
Type type = decisions.get(i).type();
if (type == Type.NO) {
return type;
} else if (type == Type.THROTTLE) {
ret = type;
}
}
return ret;
// returns most negative decision
return decisions.stream().map(Single::type).reduce(Type.YES, Type::min);
}

@Override
Expand Down
2 changes: 1 addition & 1 deletion server/src/main/java/org/elasticsearch/gateway/PrimaryShardAllocator.java
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Expand Up @@ -402,7 +402,7 @@ private static NodesToAllocate buildNodesToAllocate(
: allocation.deciders().canAllocate(shardRouting, node, allocation);
DecidedNode decidedNode = new DecidedNode(nodeShardState, decision);
(switch (decision.type()) {
case YES -> yesNodeShards;
case YES, NOT_PREFERRED -> yesNodeShards;
case THROTTLE -> throttledNodeShards;
case NO -> noNodeShards;
}).add(decidedNode);
Expand Down
20 changes: 17 additions & 3 deletions ...st/java/org/elasticsearch/cluster/routing/allocation/decider/AllocationDecidersTests.java
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Expand Up @@ -56,11 +56,23 @@ public void testCheckAllDecidersBeforeReturningYes() {
}

public void testCheckAllDecidersBeforeReturningThrottle() {
var allDecisions = generateDecisions(Decision.THROTTLE, () -> Decision.YES);
var allDecisions = generateDecisions(Decision.THROTTLE, () -> randomFrom(Decision.YES, Decision.NOT_PREFERRED));
var debugMode = randomFrom(RoutingAllocation.DebugMode.values());
var expectedDecision = switch (debugMode) {
case OFF -> Decision.THROTTLE;
case EXCLUDE_YES_DECISIONS -> new Decision.Multi().add(Decision.THROTTLE);
case EXCLUDE_YES_DECISIONS -> collectToMultiDecision(allDecisions, d -> d.type() != Decision.Type.YES);
case ON -> collectToMultiDecision(allDecisions);
};

verifyDecidersCall(debugMode, allDecisions, allDecisions.size(), expectedDecision);
}

public void testCheckAllDecidersBeforeReturningNotPreferred() {
var allDecisions = generateDecisions(Decision.NOT_PREFERRED, () -> Decision.YES);
var debugMode = randomFrom(RoutingAllocation.DebugMode.values());
var expectedDecision = switch (debugMode) {
case OFF -> Decision.NOT_PREFERRED;
case EXCLUDE_YES_DECISIONS -> new Decision.Multi().add(Decision.NOT_PREFERRED);
case ON -> collectToMultiDecision(allDecisions);
};

Expand All @@ -69,7 +81,7 @@ public void testCheckAllDecidersBeforeReturningThrottle() {

public void testExitsAfterFirstNoDecision() {
var expectedDecision = randomFrom(Decision.NO, Decision.single(Decision.Type.NO, "no with label", "explanation"));
var allDecisions = generateDecisions(expectedDecision, () -> randomFrom(Decision.YES, Decision.THROTTLE));
var allDecisions = generateDecisions(expectedDecision, () -> randomFrom(Decision.YES, Decision.NOT_PREFERRED, Decision.THROTTLE));
var expectedCalls = allDecisions.indexOf(expectedDecision) + 1;

verifyDecidersCall(RoutingAllocation.DebugMode.OFF, allDecisions, expectedCalls, expectedDecision);
Expand All @@ -79,6 +91,7 @@ public void testCollectsAllDecisionsForDebugModeOn() {
var allDecisions = generateDecisions(
() -> randomFrom(
Decision.YES,
Decision.NOT_PREFERRED,
Decision.THROTTLE,
Decision.single(Decision.Type.THROTTLE, "throttle with label", "explanation"),
Decision.NO,
Expand All @@ -94,6 +107,7 @@ public void testCollectsNoAndThrottleDecisionsForDebugModeExcludeYesDecisions()
var allDecisions = generateDecisions(
() -> randomFrom(
Decision.YES,
Decision.NOT_PREFERRED,
Decision.THROTTLE,
Decision.single(Decision.Type.THROTTLE, "throttle with label", "explanation"),
Decision.NO,
Expand Down
35 changes: 16 additions & 19 deletions server/src/test/java/org/elasticsearch/cluster/routing/allocation/decider/DecisionTests.java
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Expand Up @@ -9,10 +9,13 @@

package org.elasticsearch.cluster.routing.allocation.decider;

import org.elasticsearch.cluster.routing.allocation.decider.Decision.Type;
import org.elasticsearch.test.ESTestCase;
import org.elasticsearch.test.EnumSerializationTestUtils;

import java.util.List;

import static org.elasticsearch.cluster.routing.allocation.decider.Decision.Type.NO;
import static org.elasticsearch.cluster.routing.allocation.decider.Decision.Type.NOT_PREFERRED;
import static org.elasticsearch.cluster.routing.allocation.decider.Decision.Type.THROTTLE;
import static org.elasticsearch.cluster.routing.allocation.decider.Decision.Type.YES;

Expand All @@ -21,23 +24,17 @@
*/
public class DecisionTests extends ESTestCase {

/**
* Tests {@link Type#higherThan(Type)}
*/
public void testHigherThan() {
// test YES type
assertTrue(YES.higherThan(NO));
assertTrue(YES.higherThan(THROTTLE));
assertFalse(YES.higherThan(YES));

// test THROTTLE type
assertTrue(THROTTLE.higherThan(NO));
assertFalse(THROTTLE.higherThan(THROTTLE));
assertFalse(THROTTLE.higherThan(YES));

// test NO type
assertFalse(NO.higherThan(NO));
assertFalse(NO.higherThan(THROTTLE));
assertFalse(NO.higherThan(YES));
public void testTypeEnumOrder() {
EnumSerializationTestUtils.assertEnumSerialization(Decision.Type.class, NO, THROTTLE, NOT_PREFERRED, YES);
}

public void testTypeHigherThan() {
assertTrue(YES.higherThan(NOT_PREFERRED) && NOT_PREFERRED.higherThan(THROTTLE) && THROTTLE.higherThan(NO));
}

public void testTypeAllowed() {
List.of(NOT_PREFERRED, YES).forEach(d -> assertTrue(d.allowed()));
List.of(NO, THROTTLE).forEach(d -> assertFalse(d.allowed()));
}

}