1. cluser概述

One of the main roles of the master is to decide which shards to allocate to which nodes, and when to move shards between nodes in order to rebalance the cluster.

2. ClusterModule模塊的作用

Configures classes and services that affect the entire cluster

3.重點類介紹：

? 3.1 配置類Decider

　　各種Decider關系如下

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以EnableAllocationDecider.java為例：

public static final Setting<Allocation> CLUSTER_ROUTING_ALLOCATION_ENABLE_SETTING =new Setting<>("cluster.routing.allocation.enable", Allocation.ALL.toString(), Allocation::parse,Property.Dynamic, Property.NodeScope);public static final Setting<Allocation> INDEX_ROUTING_ALLOCATION_ENABLE_SETTING =new Setting<>("index.routing.allocation.enable", Allocation.ALL.toString(), Allocation::parse,Property.Dynamic, Property.IndexScope);public static final Setting<Rebalance> CLUSTER_ROUTING_REBALANCE_ENABLE_SETTING =new Setting<>("cluster.routing.rebalance.enable", Rebalance.ALL.toString(), Rebalance::parse,Property.Dynamic, Property.NodeScope);public static final Setting<Rebalance> INDEX_ROUTING_REBALANCE_ENABLE_SETTING =new Setting<>("index.routing.rebalance.enable", Rebalance.ALL.toString(), Rebalance::parse,Property.Dynamic, Property.IndexScope);private volatile Rebalance enableRebalance;private volatile Allocation enableAllocation;

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Decider的使用

ClusterModule.java public static Collection<AllocationDecider> createAllocationDeciders(Settings settings, ClusterSettings clusterSettings,List<ClusterPlugin> clusterPlugins) {// collect deciders by class so that we can detect duplicatesMap<Class, AllocationDecider> deciders = new LinkedHashMap<>();addAllocationDecider(deciders, new MaxRetryAllocationDecider(settings));addAllocationDecider(deciders, new ResizeAllocationDecider(settings));addAllocationDecider(deciders, new ReplicaAfterPrimaryActiveAllocationDecider(settings));addAllocationDecider(deciders, new RebalanceOnlyWhenActiveAllocationDecider(settings));addAllocationDecider(deciders, new ClusterRebalanceAllocationDecider(settings, clusterSettings));addAllocationDecider(deciders, new ConcurrentRebalanceAllocationDecider(settings, clusterSettings));addAllocationDecider(deciders, new EnableAllocationDecider(settings, clusterSettings));addAllocationDecider(deciders, new NodeVersionAllocationDecider(settings));addAllocationDecider(deciders, new SnapshotInProgressAllocationDecider(settings));addAllocationDecider(deciders, new RestoreInProgressAllocationDecider(settings));addAllocationDecider(deciders, new FilterAllocationDecider(settings, clusterSettings));addAllocationDecider(deciders, new SameShardAllocationDecider(settings, clusterSettings));addAllocationDecider(deciders, new DiskThresholdDecider(settings, clusterSettings));addAllocationDecider(deciders, new ThrottlingAllocationDecider(settings, clusterSettings));addAllocationDecider(deciders, new ShardsLimitAllocationDecider(settings, clusterSettings));addAllocationDecider(deciders, new AwarenessAllocationDecider(settings, clusterSettings));clusterPlugins.stream().flatMap(p -> p.createAllocationDeciders(settings, clusterSettings).stream()).forEach(d -> addAllocationDecider(deciders, d));return deciders.values();}

3.2 配置類Allocator

實現類ShardsAllocator

使用

private static ShardsAllocator createShardsAllocator(Settings settings, ClusterSettings clusterSettings,List<ClusterPlugin> clusterPlugins) {Map<String, Supplier<ShardsAllocator>> allocators = new HashMap<>();allocators.put(BALANCED_ALLOCATOR, () -> new BalancedShardsAllocator(settings, clusterSettings));for (ClusterPlugin plugin : clusterPlugins) {plugin.getShardsAllocators(settings, clusterSettings).forEach((k, v) -> {if (allocators.put(k, v) != null) {throw new IllegalArgumentException("ShardsAllocator [" + k + "] already defined");}});}String allocatorName = SHARDS_ALLOCATOR_TYPE_SETTING.get(settings);Supplier<ShardsAllocator> allocatorSupplier = allocators.get(allocatorName);if (allocatorSupplier == null) {throw new IllegalArgumentException("Unknown ShardsAllocator [" + allocatorName + "]");}return Objects.requireNonNull(allocatorSupplier.get(),"ShardsAllocator factory for [" + allocatorName + "] returned null");}

3.3 服務類

ClusterService.java @Overrideprotected synchronized void doStart() {clusterApplierService.start();masterService.start();}

分別調用

2.3.1clusterApplierService

@Overrideprotected synchronized void doStart() {Objects.requireNonNull(nodeConnectionsService, "please set the node connection service before starting");Objects.requireNonNull(state.get(), "please set initial state before starting");addListener(localNodeMasterListeners);threadPoolExecutor = EsExecutors.newSinglePrioritizing(nodeName + "/" + CLUSTER_UPDATE_THREAD_NAME,daemonThreadFactory(settings, CLUSTER_UPDATE_THREAD_NAME),threadPool.getThreadContext(),threadPool.scheduler());}

3.3.2?masterService

@Overrideprotected synchronized void doStart() {Objects.requireNonNull(clusterStatePublisher, "please set a cluster state publisher before starting");Objects.requireNonNull(clusterStateSupplier, "please set a cluster state supplier before starting");threadPoolExecutor = EsExecutors.newSinglePrioritizing(nodeName + "/" + MASTER_UPDATE_THREAD_NAME,daemonThreadFactory(settings, MASTER_UPDATE_THREAD_NAME),threadPool.getThreadContext(),threadPool.scheduler());taskBatcher = new Batcher(logger, threadPoolExecutor);}

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轉載于:https://www.cnblogs.com/davidwang456/p/10102927.html

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