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| Introduction |
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| <b>1.</b> |
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| Legal Notice |
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| <b>2.</b> |
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| Preface |
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| <b>3.</b> |
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| Project Info |
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| <b>4.</b> |
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| Messaging Concepts |
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| <b>5.</b> |
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| Architecture |
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| <b>6.</b> |
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| Using the Server |
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| <b>7.</b> |
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| Using JMS |
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| <a href="./using-core.html"> |
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| <b>8.</b> |
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| Using Core |
| </a> |
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| <li class="chapter " data-level="9" data-path="jms-core-mapping.html"> |
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| <a href="./jms-core-mapping.html"> |
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| <b>9.</b> |
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| Mapping JMS Concepts to the Core API |
| </a> |
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| </li> |
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| <li class="chapter " data-level="10" data-path="client-classpath.html"> |
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| <a href="./client-classpath.html"> |
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| <b>10.</b> |
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| The Client Classpath |
| </a> |
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| <li class="chapter " data-level="11" data-path="examples.html"> |
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| <b>11.</b> |
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| Examples |
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| <li class="chapter " data-level="12" data-path="wildcard-routing.html"> |
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| <a href="./wildcard-routing.html"> |
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| <b>12.</b> |
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| Routing Messages With Wild Cards |
| </a> |
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| </li> |
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| <li class="chapter " data-level="13" data-path="wildcard-syntax.html"> |
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| <a href="./wildcard-syntax.html"> |
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| <b>13.</b> |
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| Understanding the Apache ActiveMQ Artemis Wildcard Syntax |
| </a> |
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| </li> |
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| <li class="chapter " data-level="14" data-path="filter-expressions.html"> |
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| <a href="./filter-expressions.html"> |
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| <b>14.</b> |
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| Filter Expressions |
| </a> |
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| </li> |
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| <li class="chapter " data-level="15" data-path="persistence.html"> |
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| <a href="./persistence.html"> |
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| <b>15.</b> |
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| Persistence |
| </a> |
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| <a href="./configuring-transports.html"> |
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| <b>16.</b> |
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| Configuring Transports |
| </a> |
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| </li> |
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| <li class="chapter " data-level="17" data-path="connection-ttl.html"> |
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| <a href="./connection-ttl.html"> |
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| <b>17.</b> |
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| Detecting Dead Connections |
| </a> |
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| </li> |
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| <li class="chapter " data-level="18" data-path="slow-consumers.html"> |
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| <a href="./slow-consumers.html"> |
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| <b>18.</b> |
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| Detecting Slow Consumers |
| </a> |
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| </li> |
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| <li class="chapter " data-level="19" data-path="transaction-config.html"> |
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| <a href="./transaction-config.html"> |
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| <b>19.</b> |
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| Resource Manager Configuration |
| </a> |
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| </li> |
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| <li class="chapter " data-level="20" data-path="flow-control.html"> |
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| <a href="./flow-control.html"> |
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| <b>20.</b> |
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| Flow Control |
| </a> |
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| </li> |
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| <li class="chapter " data-level="21" data-path="send-guarantees.html"> |
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| <a href="./send-guarantees.html"> |
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| <b>21.</b> |
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| Guarantees of sends and commits |
| </a> |
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| </li> |
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| <li class="chapter " data-level="22" data-path="undelivered-messages.html"> |
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| <a href="./undelivered-messages.html"> |
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| <b>22.</b> |
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| Message Redelivery and Undelivered Messages |
| </a> |
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| </li> |
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| <li class="chapter " data-level="23" data-path="message-expiry.html"> |
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| <a href="./message-expiry.html"> |
| <i class="fa fa-check"></i> |
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| <b>23.</b> |
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| Message Expiry |
| </a> |
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| </li> |
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| <li class="chapter " data-level="24" data-path="large-messages.html"> |
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| <a href="./large-messages.html"> |
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| <b>24.</b> |
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| Large Messages |
| </a> |
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| </li> |
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| <li class="chapter " data-level="25" data-path="paging.html"> |
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| <a href="./paging.html"> |
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| <b>25.</b> |
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| Paging |
| </a> |
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| </li> |
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| <li class="chapter " data-level="26" data-path="queue-attributes.html"> |
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| <a href="./queue-attributes.html"> |
| <i class="fa fa-check"></i> |
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| <b>26.</b> |
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| Queue Attributes |
| </a> |
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| </li> |
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| <li class="chapter " data-level="27" data-path="scheduled-messages.html"> |
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| <a href="./scheduled-messages.html"> |
| <i class="fa fa-check"></i> |
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| <b>27.</b> |
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| Scheduled Messages |
| </a> |
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| </li> |
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| <li class="chapter " data-level="28" data-path="last-value-queues.html"> |
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| <a href="./last-value-queues.html"> |
| <i class="fa fa-check"></i> |
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| <b>28.</b> |
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| Last-Value Queues |
| </a> |
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| </li> |
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| <li class="chapter " data-level="29" data-path="message-grouping.html"> |
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| <a href="./message-grouping.html"> |
| <i class="fa fa-check"></i> |
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| <b>29.</b> |
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| Message Grouping |
| </a> |
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| </li> |
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| <li class="chapter " data-level="30" data-path="pre-acknowledge.html"> |
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| <a href="./pre-acknowledge.html"> |
| <i class="fa fa-check"></i> |
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| <b>30.</b> |
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| Extra Acknowledge Modes |
| </a> |
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| </li> |
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| <li class="chapter " data-level="31" data-path="management.html"> |
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| <a href="./management.html"> |
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| <b>31.</b> |
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| Management |
| </a> |
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| </li> |
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| <li class="chapter " data-level="32" data-path="security.html"> |
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| <a href="./security.html"> |
| <i class="fa fa-check"></i> |
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| <b>32.</b> |
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| Security |
| </a> |
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| </li> |
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| <li class="chapter " data-level="33" data-path="resource-limits.html"> |
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| <a href="./resource-limits.html"> |
| <i class="fa fa-check"></i> |
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| <b>33.</b> |
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| Resource Limits |
| </a> |
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| </li> |
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| <li class="chapter " data-level="34" data-path="jms-bridge.html"> |
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| <a href="./jms-bridge.html"> |
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| <b>34.</b> |
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| The JMS Bridge |
| </a> |
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| </li> |
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| <li class="chapter " data-level="35" data-path="client-reconnection.html"> |
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| <a href="./client-reconnection.html"> |
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| <b>35.</b> |
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| Client Reconnection and Session Reattachment |
| </a> |
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| </li> |
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| <li class="chapter " data-level="36" data-path="diverts.html"> |
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| <a href="./diverts.html"> |
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| <b>36.</b> |
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| Diverting and Splitting Message Flows |
| </a> |
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| </li> |
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| <li class="chapter " data-level="37" data-path="core-bridges.html"> |
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| <a href="./core-bridges.html"> |
| <i class="fa fa-check"></i> |
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| <b>37.</b> |
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| Core Bridges |
| </a> |
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| </li> |
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| <li class="chapter " data-level="38" data-path="duplicate-detection.html"> |
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| <a href="./duplicate-detection.html"> |
| <i class="fa fa-check"></i> |
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| <b>38.</b> |
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| Duplicate Message Detection |
| </a> |
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| </li> |
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| <li class="chapter " data-level="39" data-path="clusters.html"> |
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| <a href="./clusters.html"> |
| <i class="fa fa-check"></i> |
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| <b>39.</b> |
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| Clusters |
| </a> |
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| </li> |
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| <li class="chapter " data-level="40" data-path="ha.html"> |
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| <a href="./ha.html"> |
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| <b>40.</b> |
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| High Availability and Failover |
| </a> |
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| </li> |
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| <li class="chapter " data-level="41" data-path="graceful-shutdown.html"> |
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| <a href="./graceful-shutdown.html"> |
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| <b>41.</b> |
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| Graceful Server Shutdown |
| </a> |
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| </li> |
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| <li class="chapter " data-level="42" data-path="libaio.html"> |
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| <a href="./libaio.html"> |
| <i class="fa fa-check"></i> |
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| <b>42.</b> |
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| Libaio Native Libraries |
| </a> |
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| </li> |
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| <li class="chapter active" data-level="43" data-path="thread-pooling.html"> |
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| <a href="./thread-pooling.html"> |
| <i class="fa fa-check"></i> |
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| <b>43.</b> |
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| Thread management |
| </a> |
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| </li> |
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| <li class="chapter " data-level="44" data-path="logging.html"> |
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| <a href="./logging.html"> |
| <i class="fa fa-check"></i> |
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| <b>44.</b> |
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| Logging |
| </a> |
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| </li> |
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| <li class="chapter " data-level="45" data-path="rest.html"> |
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| <a href="./rest.html"> |
| <i class="fa fa-check"></i> |
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| <b>45.</b> |
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| REST Interface |
| </a> |
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| </li> |
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| <li class="chapter " data-level="46" data-path="embedding-activemq.html"> |
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| <a href="./embedding-activemq.html"> |
| <i class="fa fa-check"></i> |
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| <b>46.</b> |
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| Embedding Apache ActiveMQ Artemis |
| </a> |
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| </li> |
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| <li class="chapter " data-level="47" data-path="karaf.html"> |
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| <a href="./karaf.html"> |
| <i class="fa fa-check"></i> |
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| <b>47.</b> |
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| Apache Karaf |
| </a> |
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| </li> |
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| <li class="chapter " data-level="48" data-path="spring-integration.html"> |
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| <a href="./spring-integration.html"> |
| <i class="fa fa-check"></i> |
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| <b>48.</b> |
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| Spring Integration |
| </a> |
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| </li> |
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| <li class="chapter " data-level="49" data-path="aerogear-integration.html"> |
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| <a href="./aerogear-integration.html"> |
| <i class="fa fa-check"></i> |
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| <b>49.</b> |
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| AeroGear Integration |
| </a> |
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| </li> |
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| <li class="chapter " data-level="50" data-path="vertx-integration.html"> |
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| <a href="./vertx-integration.html"> |
| <i class="fa fa-check"></i> |
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| <b>50.</b> |
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| VertX Integration |
| </a> |
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| </li> |
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| <li class="chapter " data-level="51" data-path="intercepting-operations.html"> |
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| <a href="./intercepting-operations.html"> |
| <i class="fa fa-check"></i> |
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| <b>51.</b> |
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| Intercepting Operations |
| </a> |
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| </li> |
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| <li class="chapter " data-level="52" data-path="protocols-interoperability.html"> |
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| <a href="./protocols-interoperability.html"> |
| <i class="fa fa-check"></i> |
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| <b>52.</b> |
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| Protocols and Interoperability |
| </a> |
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| </li> |
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| <li class="chapter " data-level="53" data-path="tools.html"> |
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| <a href="./tools.html"> |
| <i class="fa fa-check"></i> |
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| <b>53.</b> |
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| Tools |
| </a> |
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| </li> |
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| <li class="chapter " data-level="54" data-path="maven-plugin.html"> |
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| <a href="./maven-plugin.html"> |
| <i class="fa fa-check"></i> |
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| <b>54.</b> |
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| Maven Plugin |
| </a> |
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| </li> |
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| <li class="chapter " data-level="55" data-path="perf-tuning.html"> |
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| <a href="./perf-tuning.html"> |
| <i class="fa fa-check"></i> |
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| <b>55.</b> |
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| Troubleshooting and Performance Tuning |
| </a> |
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| |
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| </li> |
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| <li class="chapter " data-level="56" data-path="configuration-index.html"> |
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| <a href="./configuration-index.html"> |
| <i class="fa fa-check"></i> |
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| <b>56.</b> |
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| Configuration Reference |
| </a> |
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| </li> |
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| Published with GitBook |
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| <!-- Title --> |
| <h1> |
| <i class="fa fa-circle-o-notch fa-spin"></i> |
| <a href="./" >ActiveMQ Artemis Documentation</a> |
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| <section class="normal" id="section-"> |
| |
| <h1 id="thread-management">Thread management</h1> |
| <p>This chapter describes how Apache ActiveMQ Artemis uses and pools threads and how you |
| can manage them.</p> |
| <p>First we'll discuss how threads are managed and used on the server side, |
| then we'll look at the client side.</p> |
| <h2 id="server-side-thread-management">Server-Side Thread Management</h2> |
| <p>Each Apache ActiveMQ Artemis Server maintains a single thread pool for general use, and |
| a scheduled thread pool for scheduled use. A Java scheduled thread pool |
| cannot be configured to use a standard thread pool, otherwise we could |
| use a single thread pool for both scheduled and non scheduled activity.</p> |
| <p>A separate thread pool is also used to service connections. Apache ActiveMQ Artemis can |
| use "old" (blocking) IO or "new" (non-blocking) IO also called NIO. Both |
| of these options use a separate thread pool, but each of them behaves |
| uniquely.</p> |
| <p>Since old IO requires a thread per connection its thread pool is |
| unbounded. The thread pool is created via <code>java.util.concurrent.Executors.newCachedThreadPool(ThreadFactory)</code>. |
| As the JavaDoc for this method states: “Creates a thread pool that |
| creates new threads as needed, but will reuse previously constructed |
| threads when they are available, and uses the provided ThreadFactory to |
| create new threads when needed.” Threads from this pool which are idle |
| for more than 60 seconds will time out and be removed. If old IO |
| connections were serviced from the standard pool the pool would easily |
| get exhausted if too many connections were made, resulting in the server |
| "hanging" since it has no remaining threads to do anything else. |
| However, even an unbounded thread pool can run into trouble if it |
| becomes too large. If you require the server to handle many concurrent |
| connections you should use NIO, not old IO.</p> |
| <p>When using new IO (NIO), Apache ActiveMQ Artemis will, by default, cap its thread pool |
| at three times the number of cores (or hyper-threads) as reported by <code>Runtime.getRuntime().availableProcessors()</code> for processing |
| incoming packets. To override this value, you can set the number of |
| threads by specifying the parameter <code>nioRemotingThreads</code> in the |
| transport configuration. See the <a href="configuring-transports.html">configuring transports</a> |
| for more information on this.</p> |
| <p>There are also a small number of other places where threads are used |
| directly, we'll discuss each in turn.</p> |
| <h3 id="server-scheduled-thread-pool">Server Scheduled Thread Pool</h3> |
| <p>The server scheduled thread pool is used for most activities on the |
| server side that require running periodically or with delays. It maps |
| internally to a <code>java.util.concurrent.ScheduledThreadPoolExecutor</code> |
| instance.</p> |
| <p>The maximum number of thread used by this pool is configure in |
| <code>broker.xml</code> with the <code>scheduled-thread-pool-max-size</code> |
| parameter. The default value is <code>5</code> threads. A small number of threads |
| is usually sufficient for this pool.</p> |
| <h3 id="general-purpose-server-thread-pool">General Purpose Server Thread Pool</h3> |
| <p>This general purpose thread pool is used for most asynchronous actions |
| on the server side. It maps internally to a |
| <code>java.util.concurrent.ThreadPoolExecutor</code> instance.</p> |
| <p>The maximum number of thread used by this pool is configure in |
| <code>broker.xml</code> with the <code>thread-pool-max-size</code> parameter.</p> |
| <p>If a value of <code>-1</code> is used this signifies that the thread pool has no |
| upper bound and new threads will be created on demand if there are not |
| enough threads available to satisfy a request. If activity later |
| subsides then threads are timed-out and closed.</p> |
| <p>If a value of <code>n</code> where <code>n</code>is a positive integer greater than zero is |
| used this signifies that the thread pool is bounded. If more requests |
| come in and there are no free threads in the pool and the pool is full |
| then requests will block until a thread becomes available. It is |
| recommended that a bounded thread pool is used with caution since it can |
| lead to dead-lock situations if the upper bound is chosen to be too low.</p> |
| <p>The default value for <code>thread-pool-max-size</code> is <code>30</code>.</p> |
| <p>See the <a href="http://docs.oracle.com/javase/6/docs/api/java/util/concurrent/ThreadPoolExecutor.htm" target="_blank">J2SE |
| javadoc</a> |
| for more information on unbounded (cached), and bounded (fixed) thread |
| pools.</p> |
| <h3 id="expiry-reaper-thread">Expiry Reaper Thread</h3> |
| <p>A single thread is also used on the server side to scan for expired |
| messages in queues. We cannot use either of the thread pools for this |
| since this thread needs to run at its own configurable priority.</p> |
| <p>For more information on configuring the reaper, please see <a href="message-expiry.html">message expiry</a>.</p> |
| <h3 id="asynchronous-io">Asynchronous IO</h3> |
| <p>Asynchronous IO has a thread pool for receiving and dispatching events |
| out of the native layer. You will find it on a thread dump with the |
| prefix ActiveMQ-AIO-poller-pool. Apache ActiveMQ Artemis uses one thread per opened |
| file on the journal (there is usually one).</p> |
| <p>There is also a single thread used to invoke writes on libaio. We do |
| that to avoid context switching on libaio that would cause performance |
| issues. You will find this thread on a thread dump with the prefix |
| ActiveMQ-AIO-writer-pool.</p> |
| <h2 id="client-side-thread-management">Client-Side Thread Management</h2> |
| <p>On the client side, Apache ActiveMQ Artemis maintains a single static scheduled thread |
| pool and a single static general thread pool for use by all clients |
| using the same classloader in that JVM instance.</p> |
| <p>The static scheduled thread pool has a maximum size of <code>5</code> threads, and |
| the general purpose thread pool has an unbounded maximum size.</p> |
| <p>If required Apache ActiveMQ Artemis can also be configured so that each |
| <code>ClientSessionFactory</code> instance does not use these static pools but |
| instead maintains its own scheduled and general purpose pool. Any |
| sessions created from that <code>ClientSessionFactory</code> will use those pools |
| instead.</p> |
| <p>To configure a <code>ClientSessionFactory</code> instance to use its own pools, |
| simply use the appropriate setter methods immediately after creation, |
| for example:</p> |
| <pre><code class="lang-java">ServerLocator locator = ActiveMQClient.createServerLocatorWithoutHA(...) |
| |
| ClientSessionFactory myFactory = locator.createClientSessionFactory(); |
| |
| myFactory.setUseGlobalPools(<span class="hljs-keyword">false</span>); |
| |
| myFactory.setScheduledThreadPoolMaxSize(<span class="hljs-number">10</span>); |
| |
| myFactory.setThreadPoolMaxSize(-<span class="hljs-number">1</span>); |
| </code></pre> |
| <p>If you're using the JMS API, you can set the same parameters on the |
| ClientSessionFactory and use it to create the <code>ConnectionFactory</code> |
| instance, for example:</p> |
| <pre><code class="lang-java">ConnectionFactory myConnectionFactory = ActiveMQJMSClient.createConnectionFactory(myFactory); |
| </code></pre> |
| <p>If you're using JNDI to instantiate <code>ActiveMQConnectionFactory</code> |
| instances, you can also set these parameters in the JNDI context |
| environment, e.g. <code>jndi.properties</code>. Here's a simple example using the |
| "ConnectionFactory" connection factory which is available in the context |
| by default:</p> |
| <pre><code>java.naming.factory.initial=org.apache.activemq.artemis.jndi.ActiveMQInitialContextFactory |
| |
| java.naming.provider.url=tcp://localhost:61616 |
| |
| connection.ConnectionFactory.useGlobalPools=false |
| |
| connection.ConnectionFactory.scheduledThreadPoolMaxSize=10 |
| |
| connection.ConnectionFactory.threadPoolMaxSize=-1 |
| </code></pre> |
| |
| </section> |
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