This closes #4966

artemis-core-client/src/main/java/org/apache/activemq/artemis/api/config/ActiveMQDefaultConfiguration.java

@@ -512,6 +512,8 @@ public final class ActiveMQDefaultConfiguration {
 
    public static final long DEFAULT_GLOBAL_MAX_MESSAGES = -1;
 
+   public static final int INITIAL_QUEUE_BUFFER_SIZE = 8192;
+
    public static final int DEFAULT_MAX_DISK_USAGE;
 
    static {
@@ -1967,4 +1969,10 @@ public final class ActiveMQDefaultConfiguration {
       return DEFAULT_MIRROR_PAGE_TRANSACTION;
    }
 
+   /**
+    * the initial size of the intermediate message buffer used for queues
+    */
+   public static int getInitialQueueBufferSize() {
+      return INITIAL_QUEUE_BUFFER_SIZE;
+   }
 }

artemis-core-client/src/main/java/org/apache/activemq/artemis/api/core/management/AddressSettingsInfo.java

@@ -309,6 +309,11 @@ public final class AddressSettingsInfo {
    }
    private boolean enableMetrics;
 
+   static {
+      META_BEAN.add(Integer.class, "initialQueueBufferSize", (t, p) -> t.initialQueueBufferSize = p, t -> t.initialQueueBufferSize);
+   }
+   private int initialQueueBufferSize;
+
 
    public static AddressSettingsInfo fromJSON(final String jsonString) {
       AddressSettingsInfo newInfo = new AddressSettingsInfo();
@@ -554,5 +559,9 @@ public final class AddressSettingsInfo {
    public boolean isEnableMetrics() {
       return enableMetrics;
    }
+
+   public int getInitialQueueBufferSize() {
+      return initialQueueBufferSize;
+   }
 }
 

artemis-server/src/main/java/org/apache/activemq/artemis/core/config/impl/Validators.java

@@ -107,6 +107,14 @@ public final class Validators {
       }
    };
 
+   public static final Validator<Number> POSITIVE_POWER_OF_TWO = (name, value) -> {
+      if ((value.longValue() & (value.longValue() - 1)) == 0 && value.longValue() > 0) {
+         return value;
+      } else {
+         throw ActiveMQMessageBundle.BUNDLE.positivePowerOfTwo(name, value);
+      }
+   };
+
    public static final Validator<Number> MINUS_ONE_OR_POSITIVE_INT = (name, value) -> {
       if (value.longValue() == -1 || (value.longValue() > 0 && value.longValue() <= Integer.MAX_VALUE)) {
          return value;

artemis-server/src/main/java/org/apache/activemq/artemis/core/deployers/impl/FileConfigurationParser.java

@@ -141,6 +141,7 @@ import static org.apache.activemq.artemis.core.config.impl.Validators.PAGE_FULL_
 import static org.apache.activemq.artemis.core.config.impl.Validators.PERCENTAGE;
 import static org.apache.activemq.artemis.core.config.impl.Validators.PERCENTAGE_OR_MINUS_ONE;
 import static org.apache.activemq.artemis.core.config.impl.Validators.POSITIVE_INT;
+import static org.apache.activemq.artemis.core.config.impl.Validators.POSITIVE_POWER_OF_TWO;
 import static org.apache.activemq.artemis.core.config.impl.Validators.ROUTING_TYPE;
 import static org.apache.activemq.artemis.core.config.impl.Validators.SLOW_CONSUMER_POLICY_TYPE;
 import static org.apache.activemq.artemis.core.config.impl.Validators.SLOW_CONSUMER_THRESHOLD_MEASUREMENT_UNIT;
@@ -388,6 +389,8 @@ public final class FileConfigurationParser extends XMLConfigurationUtil {
 
    private static final String MIRROR_PAGE_TRANSACTION = "mirror-page-transaction";
 
+   private static final String INITIAL_QUEUE_BUFFER_SIZE = "initial-queue-buffer-size";
+
    private boolean validateAIO = false;
 
    private boolean printPageMaxSizeUsed = false;
@@ -1472,6 +1475,8 @@ public final class FileConfigurationParser extends XMLConfigurationUtil {
             addressSettings.setEnableIngressTimestamp(XMLUtil.parseBoolean(child));
          } else if (ID_CACHE_SIZE.equalsIgnoreCase(name)) {
             addressSettings.setIDCacheSize(GE_ZERO.validate(ID_CACHE_SIZE, XMLUtil.parseInt(child)).intValue());
+         } else if (INITIAL_QUEUE_BUFFER_SIZE.equalsIgnoreCase(name)) {
+            addressSettings.setInitialQueueBufferSize(POSITIVE_POWER_OF_TWO.validate(INITIAL_QUEUE_BUFFER_SIZE, XMLUtil.parseInt(child)).intValue());
          }
       }
       return setting;

artemis-server/src/main/java/org/apache/activemq/artemis/core/server/ActiveMQMessageBundle.java

@@ -559,4 +559,6 @@ public interface ActiveMQMessageBundle {
    @Message(id = 229255, value = "Bridge {} cannot be {}. Current state: {}")
    ActiveMQIllegalStateException bridgeOperationCannotBeExecuted(String bridgeName, String failedOp, BridgeImpl.State currentState);
 
+   @Message(id = 229256, value = "{} must be a positive power of 2 (actual value: {})")
+   IllegalArgumentException positivePowerOfTwo(String name, Number val);
 }

artemis-server/src/main/java/org/apache/activemq/artemis/core/server/Queue.java

@@ -178,6 +178,8 @@ public interface Queue extends Bindable,CriticalComponent {
 
    long getRingSize();
 
+   int getInitialQueueBufferSize();
+
    default boolean isMirrorController() {
       return false;
    }

artemis-server/src/main/java/org/apache/activemq/artemis/core/server/impl/QueueImpl.java

@@ -213,7 +213,7 @@ public class QueueImpl extends CriticalComponentImpl implements Queue {
    // Messages will first enter intermediateMessageReferences
    // Before they are added to messageReferences
    // This is to avoid locking the queue on the producer
-   private final MpscUnboundedArrayQueue<MessageReference> intermediateMessageReferences = new MpscUnboundedArrayQueue<>(8192);
+   private final MpscUnboundedArrayQueue<MessageReference> intermediateMessageReferences;
 
    // This is where messages are stored
    protected final PriorityLinkedList<MessageReference> messageReferences = new PriorityLinkedListImpl<>(QueueImpl.NUM_PRIORITIES, MessageReferenceImpl.getSequenceComparator());
@@ -365,6 +365,8 @@ public class QueueImpl extends CriticalComponentImpl implements Queue {
 
    private volatile long createdTimestamp = -1;
 
+   private final int initialQueueBufferSize;
+
    @Override
    public boolean isSwept() {
       return swept;
@@ -753,6 +755,11 @@ public class QueueImpl extends CriticalComponentImpl implements Queue {
       }
 
       this.ringSize = queueConfiguration.getRingSize() == null ? ActiveMQDefaultConfiguration.getDefaultRingSize() : queueConfiguration.getRingSize();
+
+      this.initialQueueBufferSize = this.addressSettings.getInitialQueueBufferSize() == null
+              ? ActiveMQDefaultConfiguration.INITIAL_QUEUE_BUFFER_SIZE
+              : this.addressSettings.getInitialQueueBufferSize();
+      this.intermediateMessageReferences = new MpscUnboundedArrayQueue<>(initialQueueBufferSize);
    }
 
    // Bindable implementation -------------------------------------------------------------------------------------
@@ -1092,6 +1099,11 @@ public class QueueImpl extends CriticalComponentImpl implements Queue {
       return routingType;
    }
 
+   @Override
+   public int getInitialQueueBufferSize() {
+      return this.initialQueueBufferSize;
+   }
+
    @Override
    public void setRoutingType(RoutingType routingType) {
       if (addressInfo.getRoutingTypes().contains(routingType)) {

artemis-server/src/main/java/org/apache/activemq/artemis/core/settings/impl/AddressSettings.java

@@ -533,6 +533,12 @@ public class AddressSettings implements Mergeable<AddressSettings>, Serializable
    static {
       metaBean.add(Integer.class, "queuePrefetch", (t, p) -> t.queuePrefetch = p, t -> t.queuePrefetch);
    }
+
+   static {
+      metaBean.add(Integer.class, "initialQueueBufferSize", (t, p) -> t.initialQueueBufferSize = p, t -> t.initialQueueBufferSize);
+   }
+   private Integer initialQueueBufferSize = null;
+
    //from amq5
    //make it transient
    @Deprecated
@@ -1283,6 +1289,15 @@ public class AddressSettings implements Mergeable<AddressSettings>, Serializable
       return this;
    }
 
+   public Integer getInitialQueueBufferSize() {
+      return initialQueueBufferSize;
+   }
+
+   public AddressSettings setInitialQueueBufferSize(int initialQueueBufferSize) {
+      this.initialQueueBufferSize = initialQueueBufferSize;
+      return this;
+   }
+
    /**
     * Merge two AddressSettings instances in one instance
     *
@@ -1783,6 +1798,9 @@ public class AddressSettings implements Mergeable<AddressSettings>, Serializable
          return false;
       if (!Objects.equals(idCacheSize, that.idCacheSize))
          return false;
+      if (!Objects.equals(initialQueueBufferSize, that.initialQueueBufferSize)) {
+         return false;
+      }
       return Objects.equals(queuePrefetch, that.queuePrefetch);
    }
 
@@ -1865,11 +1883,13 @@ public class AddressSettings implements Mergeable<AddressSettings>, Serializable
       result = 31 * result + (enableIngressTimestamp != null ? enableIngressTimestamp.hashCode() : 0);
       result = 31 * result + (idCacheSize != null ? idCacheSize.hashCode() : 0);
       result = 31 * result + (queuePrefetch != null ? queuePrefetch.hashCode() : 0);
+      result = 31 * result + (initialQueueBufferSize != null ? initialQueueBufferSize.hashCode() : 0);
       return result;
    }
 
    @Override
    public String toString() {
-      return "AddressSettings{" + "addressFullMessagePolicy=" + addressFullMessagePolicy + ", maxSizeBytes=" + maxSizeBytes + ", maxReadPageBytes=" + maxReadPageBytes + ", maxReadPageMessages=" + maxReadPageMessages + ", prefetchPageBytes=" + prefetchPageBytes + ", prefetchPageMessages=" + prefetchPageMessages + ", pageLimitBytes=" + pageLimitBytes + ", pageLimitMessages=" + pageLimitMessages + ", pageFullMessagePolicy=" + pageFullMessagePolicy + ", maxSizeMessages=" + maxSizeMessages + ", pageSizeBytes=" + pageSizeBytes + ", pageMaxCache=" + pageCacheMaxSize + ", dropMessagesWhenFull=" + dropMessagesWhenFull + ", maxDeliveryAttempts=" + maxDeliveryAttempts + ", messageCounterHistoryDayLimit=" + messageCounterHistoryDayLimit + ", redeliveryDelay=" + redeliveryDelay + ", redeliveryMultiplier=" + redeliveryMultiplier + ", redeliveryCollisionAvoidanceFactor=" + redeliveryCollisionAvoidanceFactor + ", maxRedeliveryDelay=" + maxRedeliveryDelay + ", deadLetterAddress=" + deadLetterAddress + ", expiryAddress=" + expiryAddress + ", expiryDelay=" + expiryDelay + ", minExpiryDelay=" + minExpiryDelay + ", maxExpiryDelay=" + maxExpiryDelay + ", defaultLastValueQueue=" + defaultLastValueQueue + ", defaultLastValueKey=" + defaultLastValueKey + ", defaultNonDestructive=" + defaultNonDestructive + ", defaultExclusiveQueue=" + defaultExclusiveQueue + ", defaultGroupRebalance=" + defaultGroupRebalance + ", defaultGroupRebalancePauseDispatch=" + defaultGroupRebalancePauseDispatch + ", defaultGroupBuckets=" + defaultGroupBuckets + ", defaultGroupFirstKey=" + defaultGroupFirstKey + ", redistributionDelay=" + redistributionDelay + ", sendToDLAOnNoRoute=" + sendToDLAOnNoRoute + ", slowConsumerThreshold=" + slowConsumerThreshold + ", slowConsumerThresholdMeasurementUnit=" + slowConsumerThresholdMeasurementUnit + ", slowConsumerCheckPeriod=" + slowConsumerCheckPeriod + ", slowConsumerPolicy=" + slowConsumerPolicy + ", autoCreateJmsQueues=" + autoCreateJmsQueues + ", autoDeleteJmsQueues=" + autoDeleteJmsQueues + ", autoCreateJmsTopics=" + autoCreateJmsTopics + ", autoDeleteJmsTopics=" + autoDeleteJmsTopics + ", autoCreateQueues=" + autoCreateQueues + ", autoDeleteQueues=" + autoDeleteQueues + ", autoDeleteCreatedQueues=" + autoDeleteCreatedQueues + ", autoDeleteQueuesDelay=" + autoDeleteQueuesDelay + ", autoDeleteQueuesSkipUsageCheck=" + autoDeleteQueuesSkipUsageCheck + ", autoDeleteQueuesMessageCount=" + autoDeleteQueuesMessageCount + ", defaultRingSize=" + defaultRingSize + ", retroactiveMessageCount=" + retroactiveMessageCount + ", configDeleteQueues=" + configDeleteQueues + ", autoCreateAddresses=" + autoCreateAddresses + ", autoDeleteAddresses=" + autoDeleteAddresses + ", autoDeleteAddressesDelay=" + autoDeleteAddressesDelay + ", autoDeleteAddressesSkipUsageCheck=" + autoDeleteAddressesSkipUsageCheck + ", configDeleteAddresses=" + configDeleteAddresses + ", configDeleteDiverts=" + configDeleteDiverts + ", managementBrowsePageSize=" + managementBrowsePageSize + ", maxSizeBytesRejectThreshold=" + maxSizeBytesRejectThreshold + ", defaultMaxConsumers=" + defaultMaxConsumers + ", defaultPurgeOnNoConsumers=" + defaultPurgeOnNoConsumers + ", defaultConsumersBeforeDispatch=" + defaultConsumersBeforeDispatch + ", defaultDelayBeforeDispatch=" + defaultDelayBeforeDispatch + ", defaultQueueRoutingType=" + defaultQueueRoutingType + ", defaultAddressRoutingType=" + defaultAddressRoutingType + ", defaultConsumerWindowSize=" + defaultConsumerWindowSize + ", autoCreateDeadLetterResources=" + autoCreateDeadLetterResources + ", deadLetterQueuePrefix=" + deadLetterQueuePrefix + ", deadLetterQueueSuffix=" + deadLetterQueueSuffix + ", autoCreateExpiryResources=" + autoCreateExpiryResources + ", expiryQueuePrefix=" + expiryQueuePrefix + ", expiryQueueSuffix=" + expiryQueueSuffix + ", enableMetrics=" + enableMetrics + ", managementMessageAttributeSizeLimit=" + managementMessageAttributeSizeLimit + ", enableIngressTimestamp=" + enableIngressTimestamp + ", idCacheSize=" + idCacheSize + ", queuePrefetch=" + queuePrefetch + '}';
+      return "AddressSettings{" + "addressFullMessagePolicy=" + addressFullMessagePolicy + ", maxSizeBytes=" + maxSizeBytes + ", maxReadPageBytes=" + maxReadPageBytes + ", maxReadPageMessages=" + maxReadPageMessages + ", prefetchPageBytes=" + prefetchPageBytes + ", prefetchPageMessages=" + prefetchPageMessages + ", pageLimitBytes=" + pageLimitBytes + ", pageLimitMessages=" + pageLimitMessages + ", pageFullMessagePolicy=" + pageFullMessagePolicy + ", maxSizeMessages=" + maxSizeMessages + ", pageSizeBytes=" + pageSizeBytes + ", pageMaxCache=" + pageCacheMaxSize + ", dropMessagesWhenFull=" + dropMessagesWhenFull + ", maxDeliveryAttempts=" + maxDeliveryAttempts + ", messageCounterHistoryDayLimit=" + messageCounterHistoryDayLimit + ", redeliveryDelay=" + redeliveryDelay + ", redeliveryMultiplier=" + redeliveryMultiplier + ", redeliveryCollisionAvoidanceFactor=" + redeliveryCollisionAvoidanceFactor + ", maxRedeliveryDelay=" + maxRedeliveryDelay + ", deadLetterAddress=" + deadLetterAddress + ", expiryAddress=" + expiryAddress + ", expiryDelay=" + expiryDelay + ", minExpiryDelay=" + minExpiryDelay + ", maxExpiryDelay=" + maxExpiryDelay + ", defaultLastValueQueue=" + defaultLastValueQueue + ", defaultLastValueKey=" + defaultLastValueKey + ", defaultNonDestructive=" + defaultNonDestructive + ", defaultExclusiveQueue=" + defaultExclusiveQueue + ", defaultGroupRebalance=" + defaultGroupRebalance + ", defaultGroupRebalancePauseDispatch=" + defaultGroupRebalancePauseDispatch + ", defaultGroupBuckets=" + defaultGroupBuckets + ", defaultGroupFirstKey=" + defaultGroupFirstKey + ", redistributionDelay=" + redistributionDelay + ", sendToDLAOnNoRoute=" + sendToDLAOnNoRoute + ", slowConsumerThreshold=" + slowConsumerThreshold + ", slowConsumerThresholdMeasurementUnit=" + slowConsumerThresholdMeasurementUnit + ", slowConsumerCheckPeriod=" + slowConsumerCheckPeriod + ", slowConsumerPolicy=" + slowConsumerPolicy + ", autoCreateJmsQueues=" + autoCreateJmsQueues + ", autoDeleteJmsQueues=" + autoDeleteJmsQueues + ", autoCreateJmsTopics=" + autoCreateJmsTopics + ", autoDeleteJmsTopics=" + autoDeleteJmsTopics + ", autoCreateQueues=" + autoCreateQueues + ", autoDeleteQueues=" + autoDeleteQueues + ", autoDeleteCreatedQueues=" + autoDeleteCreatedQueues + ", autoDeleteQueuesDelay=" + autoDeleteQueuesDelay + ", autoDeleteQueuesSkipUsageCheck=" + autoDeleteQueuesSkipUsageCheck + ", autoDeleteQueuesMessageCount=" + autoDeleteQueuesMessageCount + ", defaultRingSize=" + defaultRingSize + ", retroactiveMessageCount=" + retroactiveMessageCount + ", configDeleteQueues=" + configDeleteQueues + ", autoCreateAddresses=" + autoCreateAddresses + ", autoDeleteAddresses=" + autoDeleteAddresses + ", autoDeleteAddressesDelay=" + autoDeleteAddressesDelay + ", autoDeleteAddressesSkipUsageCheck=" + autoDeleteAddressesSkipUsageCheck + ", configDeleteAddresses=" + configDeleteAddresses + ", configDeleteDiverts=" + configDeleteDiverts + ", managementBrowsePageSize=" + managementBrowsePageSize + ", maxSizeBytesRejectThreshold=" + maxSizeBytesRejectThreshold + ", defaultMaxConsumers=" + defaultMaxConsumers + ", defaultPurgeOnNoConsumers=" + defaultPurgeOnNoConsumers + ", defaultConsumersBeforeDispatch=" + defaultConsumersBeforeDispatch + ", defaultDelayBeforeDispatch=" + defaultDelayBeforeDispatch + ", defaultQueueRoutingType=" + defaultQueueRoutingType + ", defaultAddressRoutingType=" + defaultAddressRoutingType + ", defaultConsumerWindowSize=" + defaultConsumerWindowSize + ", autoCreateDeadLetterResources=" + autoCreateDeadLetterResources + ", deadLetterQueuePrefix=" + deadLetterQueuePrefix + ", deadLetterQueueSuffix=" + deadLetterQueueSuffix + ", autoCreateExpiryResources=" + autoCreateExpiryResources + ", expiryQueuePrefix=" + expiryQueuePrefix + ", expiryQueueSuffix=" + expiryQueueSuffix + ", enableMetrics=" + enableMetrics + ", managementMessageAttributeSizeLimit=" + managementMessageAttributeSizeLimit + ", enableIngressTimestamp=" + enableIngressTimestamp + ", idCacheSize=" + idCacheSize + ", queuePrefetch=" + queuePrefetch + ", initialQueueBufferSize=" + initialQueueBufferSize
+             + '}';
    }
 }

artemis-server/src/main/resources/schema/artemis-configuration.xsd

@@ -4465,6 +4465,15 @@
             </xsd:annotation>
          </xsd:element>
 
+         <xsd:element name="initial-queue-buffer-size" default="8192" type="xsd:int" maxOccurs="1" minOccurs="0">
+            <xsd:annotation>
+               <xsd:documentation>
+                  This will set the initial intermediate message reference buffer size for all queues on the matching address. Will use the
+                  default initial size if not configured.
+               </xsd:documentation>
+            </xsd:annotation>
+         </xsd:element>
+
       </xsd:all>
 
       <xsd:attribute name="match" type="xsd:string" use="required">

artemis-server/src/test/java/org/apache/activemq/artemis/core/config/impl/FileConfigurationTest.java

@@ -534,6 +534,7 @@ public class FileConfigurationTest extends AbstractConfigurationTestBase {
       assertTrue(conf.getAddressSettings().get("a1").isEnableMetrics());
       assertTrue(conf.getAddressSettings().get("a1").isEnableIngressTimestamp());
       assertNull(conf.getAddressSettings().get("a1").getIDCacheSize());
+      assertNull(conf.getAddressSettings().get("a1").getInitialQueueBufferSize());
 
       assertEquals("a2.1", conf.getAddressSettings().get("a2").getDeadLetterAddress().toString());
       assertTrue(conf.getAddressSettings().get("a2").isAutoCreateDeadLetterResources());
@@ -575,6 +576,7 @@ public class FileConfigurationTest extends AbstractConfigurationTestBase {
       assertFalse(conf.getAddressSettings().get("a2").isEnableMetrics());
       assertFalse(conf.getAddressSettings().get("a2").isEnableIngressTimestamp());
       assertEquals(Integer.valueOf(500), conf.getAddressSettings().get("a2").getIDCacheSize());
+      assertEquals(Integer.valueOf(128), conf.getAddressSettings().get("a2").getInitialQueueBufferSize());
 
       assertEquals(111, conf.getMirrorAckManagerQueueAttempts());
       assertEquals(222, conf.getMirrorAckManagerPageAttempts());

artemis-server/src/test/java/org/apache/activemq/artemis/core/config/impl/ValidatorsTest.java

@@ -152,4 +152,16 @@ public class ValidatorsTest {
       ValidatorsTest.success(Validators.NULL_OR_TWO_CHARACTERS, null);
    }
 
+   @Test
+   public void testPOSITIVE_POWER_OF_TWO() {
+      ValidatorsTest.failure(Validators.POSITIVE_POWER_OF_TWO, 0);
+      ValidatorsTest.failure(Validators.POSITIVE_POWER_OF_TWO, -10);
+      ValidatorsTest.failure(Validators.POSITIVE_POWER_OF_TWO, 127);
+
+      ValidatorsTest.success(Validators.POSITIVE_POWER_OF_TWO, 2);
+      ValidatorsTest.success(Validators.POSITIVE_POWER_OF_TWO, 64);
+      ValidatorsTest.success(Validators.POSITIVE_POWER_OF_TWO, 1024);
+      ValidatorsTest.success(Validators.POSITIVE_POWER_OF_TWO, 16777216);
+   }
+
 }

artemis-server/src/test/java/org/apache/activemq/artemis/core/server/impl/RoutingContextTest.java

@@ -378,6 +378,11 @@ public class RoutingContextTest {
          return 0;
       }
 
+      @Override
+      public int getInitialQueueBufferSize() {
+         return 0;
+      }
+
       @Override
       public ReferenceCounter getConsumersRefCount() {
          return null;

artemis-server/src/test/java/org/apache/activemq/artemis/core/server/impl/ScheduledDeliveryHandlerTest.java

@@ -1717,5 +1717,10 @@ public class ScheduledDeliveryHandlerTest {
       public void setExclusive(boolean exclusive) {
 
       }
+
+      @Override
+      public int getInitialQueueBufferSize() {
+         return 0;
+      }
    }
 }

artemis-server/src/test/java/org/apache/activemq/artemis/core/settings/AddressSettingsTest.java

@@ -92,6 +92,7 @@ public class AddressSettingsTest extends ServerTestBase {
       addressSettingsToMerge.setMinExpiryDelay(888L);
       addressSettingsToMerge.setMaxExpiryDelay(777L);
       addressSettingsToMerge.setIDCacheSize(5);
+      addressSettingsToMerge.setInitialQueueBufferSize(256);
 
       if (copy) {
          addressSettings = addressSettings.mergeCopy(addressSettingsToMerge);
@@ -113,6 +114,7 @@ public class AddressSettingsTest extends ServerTestBase {
       assertEquals(Long.valueOf(888), addressSettings.getMinExpiryDelay());
       assertEquals(Long.valueOf(777), addressSettings.getMaxExpiryDelay());
       assertEquals(Integer.valueOf(5), addressSettings.getIDCacheSize());
+      assertEquals(Integer.valueOf(256), addressSettings.getInitialQueueBufferSize());
    }
 
    @Test

artemis-server/src/test/resources/ConfigurationTest-full-config.xml

@@ -639,6 +639,7 @@
             <management-browse-page-size>400</management-browse-page-size>
             <management-message-attribute-size-limit>265</management-message-attribute-size-limit>
             <id-cache-size>500</id-cache-size>
+            <initial-queue-buffer-size>128</initial-queue-buffer-size>
          </address-setting>
       </address-settings>
       <resource-limit-settings>

artemis-server/src/test/resources/ConfigurationTest-xinclude-config-address-settings.xml

@@ -84,5 +84,6 @@
       <retroactive-message-count>10</retroactive-message-count>
       <enable-metrics>false</enable-metrics>
       <id-cache-size>500</id-cache-size>
+      <initial-queue-buffer-size>128</initial-queue-buffer-size>
    </address-setting>
 </address-settings>

artemis-server/src/test/resources/ConfigurationTest-xinclude-schema-config-address-settings.xml

@@ -84,5 +84,6 @@
       <retroactive-message-count>10</retroactive-message-count>
       <enable-metrics>false</enable-metrics>
       <id-cache-size>500</id-cache-size>
+      <initial-queue-buffer-size>128</initial-queue-buffer-size>
    </address-setting>
 </address-settings>

docs/user-manual/address-settings.adoc

@@ -80,6 +80,7 @@ Here an example of an `address-setting` entry that might be found in the `broker
       <enable-metrics>true</enable-metrics>
       <enable-ingress-timestamp>false</enable-ingress-timestamp>
       <id-cache-size>20000</id-cache-size>
+      <initial-queue-buffer-size>8192</initial-queue-buffer-size>
    </address-setting>
 </address-settings>
 ----
@@ -394,6 +395,11 @@ that helps to detect and prevent the processing of duplicate messages based on t
 By default, the `id-cache-size` setting inherits from the global `id-cache-size`, with a default of `20000` elements if not explicitly configured.
 Read more about xref:duplicate-detection.adoc#configuring-the-duplicate-id-cache[duplicate id cache sizes].
 
+initial-queue-buffer-size::
+defines the initial number of elements allocated initially on the JVM heap for the message reference buffer. This is allocated for each queue.
+If there are many queues that are created but unlikely to be used, this can be configured to a smaller value to prevent large initial allocation.
+By default, this value is `8192` if not explicitly configured. This must be a positive power of 2 (i.e. `0` is not an option).
+
 ## Literal Matches
 
 A _literal_ match is a match that contains wildcards but should be applied _without regard_ to those wildcards. In other words, the wildcards should be ignored and the address settings should only be applied to the literal (i.e. exact) match.

docs/user-manual/configuration-index.adoc

@@ -798,6 +798,11 @@ see `auto-create-queues` & `auto-create-addresses`
 | Number of messages a management resource can browse
 | 200
 
+
+| xref:address-settings.adoc#address-settings[initial-queue-buffer-size]
+| The number of elements in the intermediate message buffer allocated for each queue
+| 8192
+
 | xref:address-model.adoc#non-durable-subscription-queue[default-purge-on-no-consumers]
 | `purge-on-no-consumers` value if none is set on the queue
 | `false`

tests/artemis-test-support/src/main/java/org/apache/activemq/artemis/tests/unit/core/postoffice/impl/fakes/FakeQueue.java

@@ -1029,4 +1029,8 @@ public class FakeQueue extends CriticalComponentImpl implements Queue {
       return 0;
    }
 
+   @Override
+   public int getInitialQueueBufferSize() {
+      return 0;
+   }
 }

tests/integration-tests/src/test/java/org/apache/activemq/artemis/tests/integration/client/UpdateQueueTest.java

@@ -174,6 +174,7 @@ public class UpdateQueueTest extends ActiveMQTestBase {
       assertEquals(10L, queue.getDelayBeforeDispatch());
       assertEquals("newUser", queue.getUser().toString());
       assertEquals(180L, queue.getRingSize());
+      assertEquals(8192, queue.getInitialQueueBufferSize());
 
       factory = new ActiveMQConnectionFactory("vm://0");
 

tests/integration-tests/src/test/java/org/apache/activemq/artemis/tests/integration/management/ActiveMQServerControlTest.java

@@ -1247,6 +1247,14 @@ public class ActiveMQServerControlTest extends ManagementTestBase {
       assertEquals(addressSettings.getDeadLetterAddress(), info.getDeadLetterAddress());
       assertEquals(addressSettings.getExpiryAddress(), info.getExpiryAddress());
       assertEquals(addressSettings.getRedeliveryDelay(), info.getRedeliveryDelay());
+
+      addressSettings.setInitialQueueBufferSize(64);
+      returnedSettings = serverControl.addAddressSettings("foo", addressSettings.toJSON());
+      info = AddressSettings.fromJSON(returnedSettings);
+      assertEquals(addressSettings.getDeadLetterAddress(), info.getDeadLetterAddress());
+      assertEquals(addressSettings.getExpiryAddress(), info.getExpiryAddress());
+      assertEquals(addressSettings.getRedeliveryDelay(), info.getRedeliveryDelay());
+      assertEquals(addressSettings.getInitialQueueBufferSize(), info.getInitialQueueBufferSize());
    }
    @TestTemplate
    public void emptyAddressSettings() throws Exception {
@@ -1308,6 +1316,7 @@ public class ActiveMQServerControlTest extends ManagementTestBase {
       assertEquals(addressSettings.getExpiryQueuePrefix(), info.getExpiryQueuePrefix());
       assertEquals(addressSettings.getExpiryQueueSuffix(), info.getExpiryQueueSuffix());
       assertEquals(addressSettings.isEnableMetrics(), info.isEnableMetrics());
+      assertEquals(addressSettings.getInitialQueueBufferSize(), info.getInitialQueueBufferSize());
    }
    @TestTemplate
    public void testAddressSettings() throws Exception {
@@ -1368,6 +1377,7 @@ public class ActiveMQServerControlTest extends ManagementTestBase {
       String expiryQueuePrefix = RandomUtil.randomString();
       String expiryQueueSuffix = RandomUtil.randomString();
       boolean enableMetrics = RandomUtil.randomBoolean();
+      int initialQueueBufferSize = (int) Math.pow(2, 14);
 
       AddressSettings addressSettings = new AddressSettings();
       addressSettings.setDeadLetterAddress(SimpleString.of(DLA))
@@ -1422,7 +1432,8 @@ public class ActiveMQServerControlTest extends ManagementTestBase {
               .setExpiryQueueSuffix(SimpleString.of(expiryQueueSuffix))
               .setMinExpiryDelay(minExpiryDelay)
               .setMaxExpiryDelay(maxExpiryDelay)
-              .setEnableMetrics(enableMetrics);
+              .setEnableMetrics(enableMetrics)
+              .setInitialQueueBufferSize(initialQueueBufferSize);
 
 
       serverControl.addAddressSettings(addressMatch, addressSettings.toJSON());
@@ -1496,6 +1507,7 @@ public class ActiveMQServerControlTest extends ManagementTestBase {
       assertEquals(expiryQueuePrefix, info.getExpiryQueuePrefix());
       assertEquals(expiryQueueSuffix, info.getExpiryQueueSuffix());
       assertEquals(enableMetrics, info.isEnableMetrics());
+      assertEquals(initialQueueBufferSize, info.getInitialQueueBufferSize());
 
 
       addressSettings.setMaxSizeBytes(-1).setPageSizeBytes(1000);
@@ -1557,6 +1569,7 @@ public class ActiveMQServerControlTest extends ManagementTestBase {
       assertEquals(expiryQueuePrefix, info.getExpiryQueuePrefix());
       assertEquals(expiryQueueSuffix, info.getExpiryQueueSuffix());
       assertEquals(enableMetrics, info.isEnableMetrics());
+      assertEquals(initialQueueBufferSize, info.getInitialQueueBufferSize());
 
 
       addressSettings.setMaxSizeBytes(-2).setPageSizeBytes(1000);