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org.elasticsearch.cluster.routing.allocation.decider.ShardsLimitAllocationDecider Maven / Gradle / Ivy

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 * Licensed to Elasticsearch under one or more contributor
 * license agreements. See the NOTICE file distributed with
 * this work for additional information regarding copyright
 * ownership. Elasticsearch licenses this file to you under
 * the Apache License, Version 2.0 (the "License"); you may
 * not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
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package org.elasticsearch.cluster.routing.allocation.decider;

import org.elasticsearch.cluster.metadata.IndexMetaData;
import org.elasticsearch.cluster.routing.MutableShardRouting;
import org.elasticsearch.cluster.routing.RoutingNode;
import org.elasticsearch.cluster.routing.ShardRouting;
import org.elasticsearch.cluster.routing.ShardRoutingState;
import org.elasticsearch.cluster.routing.allocation.RoutingAllocation;
import org.elasticsearch.common.inject.Inject;
import org.elasticsearch.common.settings.Settings;

/**
 * This {@link AllocationDecider} limits the number of shards per node on a per
 * index basis. The allocator prevents a single node to hold more than
 * {@value #INDEX_TOTAL_SHARDS_PER_NODE} per index during the allocation
 * process. The limits of this decider can be changed in real-time via a the
 * index settings API.
 * 

* If {@value #INDEX_TOTAL_SHARDS_PER_NODE} is reset to a negative value shards * per index are unlimited per node. Shards currently in the * {@link ShardRoutingState#RELOCATING relocating} state are ignored by this * {@link AllocationDecider} until the shard changed its state to either * {@link ShardRoutingState#STARTED started}, * {@link ShardRoutingState#INITIALIZING inializing} or * {@link ShardRoutingState#UNASSIGNED unassigned} *

* Note: Reducing the number of shards per node via the index update API can * trigger relocation and significant additional load on the clusters nodes. *

*/ public class ShardsLimitAllocationDecider extends AllocationDecider { /** * Controls the maximum number of shards per index on a single elastic * search node. Negative values are interpreted as unlimited. */ public static final String INDEX_TOTAL_SHARDS_PER_NODE = "index.routing.allocation.total_shards_per_node"; @Inject public ShardsLimitAllocationDecider(Settings settings) { super(settings); } @Override public Decision canAllocate(ShardRouting shardRouting, RoutingNode node, RoutingAllocation allocation) { IndexMetaData indexMd = allocation.routingNodes().metaData().index(shardRouting.index()); int totalShardsPerNode = indexMd.settings().getAsInt(INDEX_TOTAL_SHARDS_PER_NODE, -1); if (totalShardsPerNode <= 0) { return Decision.YES; } int nodeCount = 0; for (MutableShardRouting nodeShard : node) { if (!nodeShard.index().equals(shardRouting.index())) { continue; } // don't count relocating shards... if (nodeShard.relocating()) { continue; } nodeCount++; } if (nodeCount >= totalShardsPerNode) { return Decision.NO; } return Decision.YES; } @Override public Decision canRemain(ShardRouting shardRouting, RoutingNode node, RoutingAllocation allocation) { IndexMetaData indexMd = allocation.routingNodes().metaData().index(shardRouting.index()); int totalShardsPerNode = indexMd.settings().getAsInt(INDEX_TOTAL_SHARDS_PER_NODE, -1); if (totalShardsPerNode <= 0) { return Decision.YES; } int nodeCount = 0; for (MutableShardRouting nodeShard : node) {; if (!nodeShard.index().equals(shardRouting.index())) { continue; } // don't count relocating shards... if (nodeShard.relocating()) { continue; } nodeCount++; } if (nodeCount > totalShardsPerNode) { return Decision.NO; } return Decision.YES; } }




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