rename maintenance mode to decommission

docs/content/configuration/index.md

@@ -783,8 +783,8 @@ A sample Coordinator dynamic config JSON object is shown below:
   "replicationThrottleLimit": 10,
   "emitBalancingStats": false,
   "killDataSourceWhitelist": ["wikipedia", "testDatasource"],
-  "historicalNodesInMaintenance": ["localhost:8182", "localhost:8282"],
-  "nodesInMaintenancePriority": 7
+  "decommissionNodes": ["localhost:8182", "localhost:8282"],
+  "decommissionPriority": 7
 }
 ```
 
@@ -804,8 +804,8 @@ Issuing a GET request at the same URL will return the spec that is currently in
 |`killAllDataSources`|Send kill tasks for ALL dataSources if property `druid.coordinator.kill.on` is true. If this is set to true then `killDataSourceWhitelist` must not be specified or be empty list.|false|
 |`killPendingSegmentsSkipList`|List of dataSources for which pendingSegments are _NOT_ cleaned up if property `druid.coordinator.kill.pendingSegments.on` is true. This can be a list of comma-separated dataSources or a JSON array.|none|
 |`maxSegmentsInNodeLoadingQueue`|The maximum number of segments that could be queued for loading to any given server. This parameter could be used to speed up segments loading process, especially if there are "slow" nodes in the cluster (with low loading speed) or if too much segments scheduled to be replicated to some particular node (faster loading could be preferred to better segments distribution). Desired value depends on segments loading speed, acceptable replication time and number of nodes. Value 1000 could be a start point for a rather big cluster. Default value is 0 (loading queue is unbounded) |0|
-|`historicalNodesInMaintenance`| List of Historical nodes in maintenance mode. Coordinator doesn't assign new segments on those nodes and moves segments from the nodes according to a specified priority.|none|
-|`nodesInMaintenancePriority`| Priority of segments from servers in maintenance. Coordinator takes ceil(maxSegmentsToMove * (priority / 10)) from servers in maitenance during balancing phase, i.e.:<br>0 - no segments from servers in maintenance will be processed during balancing<br>5 - 50% segments from servers in maintenance<br>10 - 100% segments from servers in maintenance<br>By leveraging the priority an operator can prevent general nodes from overload or decrease maitenance time instead.|7|
+|`decommissionNodes`| List of 'decommissioned' historical nodes. The Coordinator doesn't assign new segments to these nodes and moves segments from the nodes at the rate specified by `decommissionPriority`.|none|
+|`decommissionPriority`| Priority of how many 'move' operations will be spent towards 'decommissioning' servers by moving segments from them to non-decommissioned servers, instead of 'balancing' segments between servers. Coordinator takes ceil(maxSegmentsToMove * (priority / 10)) from servers in maitenance during balancing phase, i.e.:<br>0 - no segments from decommissioned servers will be processed during balancing<br>5 - 50% segments from decommissioned servers<br>10 - 100% segments from decommissioned servers<br>By leveraging the priority an operator can prevent general nodes from overload or decrease decommissioning time instead.|7|
 
 To view the audit history of Coordinator dynamic config issue a GET request to the URL -
 

server/src/main/java/org/apache/druid/server/coordinator/CoordinatorDynamicConfig.java

@@ -56,8 +56,8 @@ public class CoordinatorDynamicConfig
   private final boolean emitBalancingStats;
   private final boolean killAllDataSources;
   private final Set<String> killableDataSources;
-  private final Set<String> historicalNodesInMaintenance;
-  private final int nodesInMaintenancePriority;
+  private final Set<String> decommissionNodes;
+  private final int decommissionPriority;
 
   // The pending segments of the dataSources in this list are not killed.
   private final Set<String> protectedPendingSegmentDatasources;
@@ -88,8 +88,8 @@ public CoordinatorDynamicConfig(
       @JsonProperty("killAllDataSources") boolean killAllDataSources,
       @JsonProperty("killPendingSegmentsSkipList") Object protectedPendingSegmentDatasources,
       @JsonProperty("maxSegmentsInNodeLoadingQueue") int maxSegmentsInNodeLoadingQueue,
-      @JsonProperty("historicalNodesInMaintenance") Object historicalNodesInMaintenance,
-      @JsonProperty("nodesInMaintenancePriority") int nodesInMaintenancePriority
+      @JsonProperty("decommissionNodes") Object decommissionNodes,
+      @JsonProperty("decommissionPriority") int decommissionPriority
   )
   {
     this.millisToWaitBeforeDeleting = millisToWaitBeforeDeleting;
@@ -104,12 +104,12 @@ public CoordinatorDynamicConfig(
     this.killableDataSources = parseJsonStringOrArray(killableDataSources);
     this.protectedPendingSegmentDatasources = parseJsonStringOrArray(protectedPendingSegmentDatasources);
     this.maxSegmentsInNodeLoadingQueue = maxSegmentsInNodeLoadingQueue;
-    this.historicalNodesInMaintenance = parseJsonStringOrArray(historicalNodesInMaintenance);
+    this.decommissionNodes = parseJsonStringOrArray(decommissionNodes);
     Preconditions.checkArgument(
-        nodesInMaintenancePriority >= 0 && nodesInMaintenancePriority <= 10,
-        "nodesInMaintenancePriority should be in range [0, 10]"
+        decommissionPriority >= 0 && decommissionPriority <= 10,
+        "decommissionPriority should be in range [0, 10]"
     );
-    this.nodesInMaintenancePriority = nodesInMaintenancePriority;
+    this.decommissionPriority = decommissionPriority;
 
     if (this.killAllDataSources && !this.killableDataSources.isEmpty()) {
       throw new IAE("can't have killAllDataSources and non-empty killDataSourceWhitelist");
@@ -231,32 +231,33 @@ public int getMaxSegmentsInNodeLoadingQueue()
   }
 
   /**
-   * Historical nodes list in maintenance mode. Coordinator doesn't assign new segments on those nodes and moves
+   * List of historical nodes to 'decommission'. Coordinator doesn't assign new segments on those nodes and moves
    * segments from those nodes according to a specified priority.
    *
    * @return list of host:port entries
    */
   @JsonProperty
-  public Set<String> getHistoricalNodesInMaintenance()
+  public Set<String> getDecommissionNodes()
   {
-    return historicalNodesInMaintenance;
+    return decommissionNodes;
   }
 
   /**
-   * Priority of segments from servers in maintenance. Coordinator takes ceil(maxSegmentsToMove * (priority / 10))
-   * from servers in maitenance during balancing phase, i.e.:
-   * 0 - no segments from servers in maintenance will be processed during balancing
-   * 5 - 50% segments from servers in maintenance
-   * 10 - 100% segments from servers in maintenance
-   * By leveraging the priority an operator can prevent general nodes from overload or decrease maitenance time
+   * Priority of how many of 'move' operations will be spent towards 'decommissioning' servers by moving segments from
+   * them to non-decommissioned servers, instead of 'balancing' segments between servers.
+   * Coordinator takes ceil(maxSegmentsToMove * (priority / 10)) from servers in maitenance during balancing phase:
+   * 0 - no segments from decommissioned servers will be processed during balancing
+   * 5 - 50% segments from decommissioned servers
+   * 10 - 100% segments from decommissioned servers
+   * By leveraging the priority an operator can prevent general nodes from overload or decrease 'decommissioning' time
    * instead.
    *
    * @return number in range [0, 10]
    */
   @JsonProperty
-  public int getNodesInMaintenancePriority()
+  public int getDecommissionPriority()
   {
-    return nodesInMaintenancePriority;
+    return decommissionPriority;
   }
 
   @Override
@@ -275,8 +276,8 @@ public String toString()
            ", killDataSourceWhitelist=" + killableDataSources +
            ", protectedPendingSegmentDatasources=" + protectedPendingSegmentDatasources +
            ", maxSegmentsInNodeLoadingQueue=" + maxSegmentsInNodeLoadingQueue +
-           ", historicalNodesInMaintenance=" + historicalNodesInMaintenance +
-           ", nodesInMaintenancePriority=" + nodesInMaintenancePriority +
+           ", decommissionNodes=" + decommissionNodes +
+           ", decommissionPriority=" + decommissionPriority +
            '}';
   }
 
@@ -328,10 +329,10 @@ public boolean equals(Object o)
     if (!Objects.equals(protectedPendingSegmentDatasources, that.protectedPendingSegmentDatasources)) {
       return false;
     }
-    if (!Objects.equals(historicalNodesInMaintenance, that.historicalNodesInMaintenance)) {
+    if (!Objects.equals(decommissionNodes, that.decommissionNodes)) {
       return false;
     }
-    return nodesInMaintenancePriority == that.nodesInMaintenancePriority;
+    return decommissionPriority == that.decommissionPriority;
   }
 
   @Override
@@ -350,8 +351,8 @@ public int hashCode()
         maxSegmentsInNodeLoadingQueue,
         killableDataSources,
         protectedPendingSegmentDatasources,
-        historicalNodesInMaintenance,
-        nodesInMaintenancePriority
+        decommissionNodes,
+        decommissionPriority
     );
   }
 
@@ -372,7 +373,7 @@ public static class Builder
     private static final boolean DEFAULT_EMIT_BALANCING_STATS = false;
     private static final boolean DEFAULT_KILL_ALL_DATA_SOURCES = false;
     private static final int DEFAULT_MAX_SEGMENTS_IN_NODE_LOADING_QUEUE = 0;
-    private static final int DEFAULT_MAINTENANCE_MODE_SEGMENTS_PRIORITY = 7;
+    private static final int DEFAULT_DECOMMISSIONING_PRIORITY = 7;
 
     private Long millisToWaitBeforeDeleting;
     private Long mergeBytesLimit;
@@ -386,8 +387,8 @@ public static class Builder
     private Boolean killAllDataSources;
     private Object killPendingSegmentsSkipList;
     private Integer maxSegmentsInNodeLoadingQueue;
-    private Object maintenanceList;
-    private Integer maintenanceModeSegmentsPriority;
+    private Object decommissionNodes;
+    private Integer decommissionPriority;
 
     public Builder()
     {
@@ -407,8 +408,8 @@ public Builder(
         @JsonProperty("killAllDataSources") @Nullable Boolean killAllDataSources,
         @JsonProperty("killPendingSegmentsSkipList") @Nullable Object killPendingSegmentsSkipList,
         @JsonProperty("maxSegmentsInNodeLoadingQueue") @Nullable Integer maxSegmentsInNodeLoadingQueue,
-        @JsonProperty("historicalNodesInMaintenance") @Nullable Object maintenanceList,
-        @JsonProperty("nodesInMaintenancePriority") @Nullable Integer maintenanceModeSegmentsPriority
+        @JsonProperty("decommissionNodes") @Nullable Object decommissionNodes,
+        @JsonProperty("decommissionPriority") @Nullable Integer decommissionPriority
     )
     {
       this.millisToWaitBeforeDeleting = millisToWaitBeforeDeleting;
@@ -423,8 +424,8 @@ public Builder(
       this.killableDataSources = killableDataSources;
       this.killPendingSegmentsSkipList = killPendingSegmentsSkipList;
       this.maxSegmentsInNodeLoadingQueue = maxSegmentsInNodeLoadingQueue;
-      this.maintenanceList = maintenanceList;
-      this.maintenanceModeSegmentsPriority = maintenanceModeSegmentsPriority;
+      this.decommissionNodes = decommissionNodes;
+      this.decommissionPriority = decommissionPriority;
     }
 
     public Builder withMillisToWaitBeforeDeleting(long millisToWaitBeforeDeleting)
@@ -493,15 +494,15 @@ public Builder withMaxSegmentsInNodeLoadingQueue(int maxSegmentsInNodeLoadingQue
       return this;
     }
 
-    public Builder withMaintenanceList(Set<String> list)
+    public Builder withDecommissionNodes(Set<String> decommissioned)
     {
-      this.maintenanceList = list;
+      this.decommissionNodes = decommissioned;
       return this;
     }
 
-    public Builder withMaintenanceModeSegmentsPriority(Integer priority)
+    public Builder withDecommissionPriority(Integer priority)
     {
-      this.maintenanceModeSegmentsPriority = priority;
+      this.decommissionPriority = priority;
       return this;
     }
 
@@ -522,10 +523,10 @@ public CoordinatorDynamicConfig build()
           maxSegmentsInNodeLoadingQueue == null
           ? DEFAULT_MAX_SEGMENTS_IN_NODE_LOADING_QUEUE
           : maxSegmentsInNodeLoadingQueue,
-          maintenanceList,
-          maintenanceModeSegmentsPriority == null
-          ? DEFAULT_MAINTENANCE_MODE_SEGMENTS_PRIORITY
-          : maintenanceModeSegmentsPriority
+          decommissionNodes,
+          decommissionPriority == null
+          ? DEFAULT_DECOMMISSIONING_PRIORITY
+          : decommissionPriority
       );
     }
 
@@ -548,10 +549,10 @@ public CoordinatorDynamicConfig build(CoordinatorDynamicConfig defaults)
           maxSegmentsInNodeLoadingQueue == null
           ? defaults.getMaxSegmentsInNodeLoadingQueue()
           : maxSegmentsInNodeLoadingQueue,
-          maintenanceList == null ? defaults.getHistoricalNodesInMaintenance() : maintenanceList,
-          maintenanceModeSegmentsPriority == null
-          ? defaults.getNodesInMaintenancePriority()
-          : maintenanceModeSegmentsPriority
+          decommissionNodes == null ? defaults.getDecommissionNodes() : decommissionNodes,
+          decommissionPriority == null
+          ? defaults.getDecommissionPriority()
+          : decommissionPriority
       );
     }
   }

server/src/main/java/org/apache/druid/server/coordinator/DruidCoordinator.java

@@ -694,7 +694,7 @@ public CoordinatorHistoricalManagerRunnable(final int startingLeaderCounter)
                 }
 
                 // Find all historical servers, group them by subType and sort by ascending usage
-                Set<String> nodesInMaintenance = params.getCoordinatorDynamicConfig().getHistoricalNodesInMaintenance();
+                Set<String> decommissioned = params.getCoordinatorDynamicConfig().getDecommissionNodes();
                 final DruidCluster cluster = new DruidCluster();
                 for (ImmutableDruidServer server : servers) {
                   if (!loadManagementPeons.containsKey(server.getName())) {
@@ -709,7 +709,7 @@ public CoordinatorHistoricalManagerRunnable(final int startingLeaderCounter)
                       new ServerHolder(
                           server,
                           loadManagementPeons.get(server.getName()),
-                          nodesInMaintenance.contains(server.getHost())
+                          decommissioned.contains(server.getHost())
                       )
                   );
                 }

server/src/main/java/org/apache/druid/server/coordinator/ServerHolder.java

@@ -32,18 +32,18 @@ public class ServerHolder implements Comparable<ServerHolder>
   private static final Logger log = new Logger(ServerHolder.class);
   private final ImmutableDruidServer server;
   private final LoadQueuePeon peon;
-  private final boolean inMaintenance;
+  private final boolean isDecommissioned;
 
   public ServerHolder(ImmutableDruidServer server, LoadQueuePeon peon)
   {
     this(server, peon, false);
   }
 
-  public ServerHolder(ImmutableDruidServer server, LoadQueuePeon peon, boolean inMaintenance)
+  public ServerHolder(ImmutableDruidServer server, LoadQueuePeon peon, boolean isDecommissioned)
   {
     this.server = server;
     this.peon = peon;
-    this.inMaintenance = inMaintenance;
+    this.isDecommissioned = isDecommissioned;
   }
 
   public ImmutableDruidServer getServer()
@@ -82,14 +82,14 @@ public double getPercentUsed()
   }
 
   /**
-   * Historical nodes can be placed in maintenance mode, which instructs Coordinator to move segments from them
-   * according to a specified priority. The mechanism allows to drain segments from nodes which are planned for
+   * Historical nodes can be 'decommissioned', which instructs Coordinator to move segments from them
+   * according to a specified priority. The mechanism allows draining segments from nodes which are planned for
    * replacement.
-   * @return true if the node is in maitenance mode
+   * @return true if the node is being decommissioned
    */
-  public boolean isInMaintenance()
+  public boolean isDecommissioned()
   {
-    return inMaintenance;
+    return isDecommissioned;
   }
 
   public long getAvailableSize()

server/src/main/java/org/apache/druid/server/coordinator/helper/DruidCoordinatorBalancer.java

@@ -107,25 +107,25 @@ private void balanceTier(
     }
 
     /*
-      Take as much segments from maintenance servers as priority allows and find the best location for them on
+      Take as many segments from decommissioned servers as priority allows and find the best location for them on
       available servers. After that, balance segments within available servers pool.
      */
     Map<Boolean, List<ServerHolder>> partitions =
-        servers.stream().collect(Collectors.partitioningBy(ServerHolder::isInMaintenance));
-    final List<ServerHolder> maintenanceServers = partitions.get(true);
+        servers.stream().collect(Collectors.partitioningBy(ServerHolder::isDecommissioned));
+    final List<ServerHolder> decommssionedServers = partitions.get(true);
     final List<ServerHolder> availableServers = partitions.get(false);
     log.info(
-        "Found %d servers in maintenance, %d available servers servers",
-        maintenanceServers.size(),
+        "Found %d decomissioned servers, %d available servers servers",
+        decommssionedServers.size(),
         availableServers.size()
     );
 
-    if (maintenanceServers.isEmpty()) {
+    if (decommssionedServers.isEmpty()) {
       if (availableServers.size() <= 1) {
         log.info("[%s]: %d available servers servers found.  Cannot balance.", tier, availableServers.size());
       }
     } else if (availableServers.isEmpty()) {
-      log.info("[%s]: no available servers servers found during maintenance.  Cannot balance.", tier);
+      log.info("[%s]: no available servers servers found during decommissioning.  Cannot balance.", tier);
     }
 
     int numSegments = 0;
@@ -139,18 +139,18 @@ private void balanceTier(
     }
 
     final int maxSegmentsToMove = Math.min(params.getCoordinatorDynamicConfig().getMaxSegmentsToMove(), numSegments);
-    int priority = params.getCoordinatorDynamicConfig().getNodesInMaintenancePriority();
-    int maxMaintenanceSegmentsToMove = (int) Math.ceil(maxSegmentsToMove * priority / 10.0);
-    log.info("Processing %d segments from servers in maintenance mode", maxMaintenanceSegmentsToMove);
-    Pair<Integer, Integer> maintenanceResult =
-        balanceServers(params, maintenanceServers, availableServers, maxMaintenanceSegmentsToMove);
-    int maxGeneralSegmentsToMove = maxSegmentsToMove - maintenanceResult.lhs;
-    log.info("Processing %d segments from servers in general mode", maxGeneralSegmentsToMove);
+    int priority = params.getCoordinatorDynamicConfig().getDecommissionPriority();
+    int maxDecommissionedSegmentsToMove = (int) Math.ceil(maxSegmentsToMove * priority / 10.0);
+    log.info("Processing %d segments from decommissioned servers", maxDecommissionedSegmentsToMove);
+    Pair<Integer, Integer> decommissionedResult =
+        balanceServers(params, decommssionedServers, availableServers, maxDecommissionedSegmentsToMove);
+    int maxGeneralSegmentsToMove = maxSegmentsToMove - decommissionedResult.lhs;
+    log.info("Processing %d segments for balancing", maxGeneralSegmentsToMove);
     Pair<Integer, Integer> generalResult =
         balanceServers(params, availableServers, availableServers, maxGeneralSegmentsToMove);
 
-    int moved = generalResult.lhs + maintenanceResult.lhs;
-    int unmoved = generalResult.rhs + maintenanceResult.rhs;
+    int moved = generalResult.lhs + decommissionedResult.lhs;
+    int unmoved = generalResult.rhs + decommissionedResult.rhs;
     if (unmoved == maxSegmentsToMove) {
       // Cluster should be alive and constantly adjusting
       log.info("No good moves found in tier [%s]", tier);

server/src/main/java/org/apache/druid/server/coordinator/rules/BroadcastDistributionRule.java

@@ -46,7 +46,7 @@ public CoordinatorStats run(DruidCoordinator coordinator, DruidCoordinatorRuntim
     } else {
       params.getDruidCluster().getAllServers().forEach(
           eachHolder -> {
-            if (!eachHolder.isInMaintenance()
+            if (!eachHolder.isDecommissioned()
                 && colocatedDataSources.stream()
                                        .anyMatch(source -> eachHolder.getServer().getDataSource(source) != null)) {
               loadServerHolders.add(eachHolder);