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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
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.elasticsearch.cluster.routing.allocation.decider;
import org.elasticsearch.cluster.routing.RoutingNode;
import org.elasticsearch.cluster.routing.ShardRouting;
import org.elasticsearch.cluster.routing.allocation.RoutingAllocation;
import org.elasticsearch.common.inject.Inject;
import org.elasticsearch.common.settings.ClusterSettings;
import org.elasticsearch.common.settings.Setting;
import org.elasticsearch.common.settings.Settings;
/**
* {@link ThrottlingAllocationDecider} controls the recovery process per node in
* the cluster. It exposes two settings via the cluster update API that allow
* changes in real-time:
* <ul>
* <li><tt>cluster.routing.allocation.node_initial_primaries_recoveries</tt> -
* restricts the number of initial primary shard recovery operations on a single
* node. The default is <tt>4</tt></li>
* <li><tt>cluster.routing.allocation.node_concurrent_recoveries</tt> -
* restricts the number of total concurrent shards initializing on a single node. The
* default is <tt>2</tt></li>
* </ul>
* <p>
* If one of the above thresholds is exceeded per node this allocation decider
* will return {@link Decision#THROTTLE} as a hit to upstream logic to throttle
* the allocation process to prevent overloading nodes due to too many concurrent recovery
* processes.
*/
public class ThrottlingAllocationDecider extends AllocationDecider {
public static final int DEFAULT_CLUSTER_ROUTING_ALLOCATION_NODE_CONCURRENT_RECOVERIES = 2;
public static final int DEFAULT_CLUSTER_ROUTING_ALLOCATION_NODE_INITIAL_PRIMARIES_RECOVERIES = 4;
public static final String NAME = "throttling";
public static final String CLUSTER_ROUTING_ALLOCATION_CONCURRENT_RECOVERIES = "cluster.routing.allocation.concurrent_recoveries";
public static final Setting<Integer> CLUSTER_ROUTING_ALLOCATION_NODE_INITIAL_PRIMARIES_RECOVERIES_SETTING = Setting.intSetting("cluster.routing.allocation.node_initial_primaries_recoveries", DEFAULT_CLUSTER_ROUTING_ALLOCATION_NODE_INITIAL_PRIMARIES_RECOVERIES, 0, true, Setting.Scope.CLUSTER);
public static final Setting<Integer> CLUSTER_ROUTING_ALLOCATION_NODE_CONCURRENT_RECOVERIES_SETTING = new Setting<>("cluster.routing.allocation.node_concurrent_recoveries", (s) -> s.get(CLUSTER_ROUTING_ALLOCATION_CONCURRENT_RECOVERIES,Integer.toString(DEFAULT_CLUSTER_ROUTING_ALLOCATION_NODE_CONCURRENT_RECOVERIES)), (s) -> Setting.parseInt(s, 0, "cluster.routing.allocation.node_concurrent_recoveries"), true, Setting.Scope.CLUSTER);
private volatile int primariesInitialRecoveries;
private volatile int concurrentRecoveries;
@Inject
public ThrottlingAllocationDecider(Settings settings, ClusterSettings clusterSettings) {
super(settings);
this.primariesInitialRecoveries = CLUSTER_ROUTING_ALLOCATION_NODE_INITIAL_PRIMARIES_RECOVERIES_SETTING.get(settings);
this.concurrentRecoveries = CLUSTER_ROUTING_ALLOCATION_NODE_CONCURRENT_RECOVERIES_SETTING.get(settings);
logger.debug("using node_concurrent_recoveries [{}], node_initial_primaries_recoveries [{}]", concurrentRecoveries, primariesInitialRecoveries);
clusterSettings.addSettingsUpdateConsumer(CLUSTER_ROUTING_ALLOCATION_NODE_INITIAL_PRIMARIES_RECOVERIES_SETTING, this::setPrimariesInitialRecoveries);
clusterSettings.addSettingsUpdateConsumer(CLUSTER_ROUTING_ALLOCATION_NODE_CONCURRENT_RECOVERIES_SETTING, this::setConcurrentRecoveries);
}
private void setConcurrentRecoveries(int concurrentRecoveries) {
this.concurrentRecoveries = concurrentRecoveries;
}
private void setPrimariesInitialRecoveries(int primariesInitialRecoveries) {
this.primariesInitialRecoveries = primariesInitialRecoveries;
}
@Override
public Decision canAllocate(ShardRouting shardRouting, RoutingNode node, RoutingAllocation allocation) {
if (shardRouting.primary()) {
assert shardRouting.unassigned() || shardRouting.active();
if (shardRouting.unassigned()) {
// primary is unassigned, means we are going to do recovery from gateway
// count *just the primary* currently doing recovery on the node and check against concurrent_recoveries
int primariesInRecovery = 0;
for (ShardRouting shard : node) {
// when a primary shard is INITIALIZING, it can be because of *initial recovery* or *relocation from another node*
// we only count initial recoveries here, so we need to make sure that relocating node is null
if (shard.initializing() && shard.primary() && shard.relocatingNodeId() == null) {
primariesInRecovery++;
}
}
if (primariesInRecovery >= primariesInitialRecoveries) {
return allocation.decision(Decision.THROTTLE, NAME, "too many primaries currently recovering [%d], limit: [%d]",
primariesInRecovery, primariesInitialRecoveries);
} else {
return allocation.decision(Decision.YES, NAME, "below primary recovery limit of [%d]", primariesInitialRecoveries);
}
}
}
// either primary or replica doing recovery (from peer shard)
// count the number of recoveries on the node, its for both target (INITIALIZING) and source (RELOCATING)
return canAllocate(node, allocation);
}
@Override
public Decision canAllocate(RoutingNode node, RoutingAllocation allocation) {
int currentRecoveries = 0;
for (ShardRouting shard : node) {
if (shard.initializing()) {
currentRecoveries++;
}
}
if (currentRecoveries >= concurrentRecoveries) {
return allocation.decision(Decision.THROTTLE, NAME, "too many shards currently recovering [%d], limit: [%d]",
currentRecoveries, concurrentRecoveries);
} else {
return allocation.decision(Decision.YES, NAME, "below shard recovery limit of [%d]", concurrentRecoveries);
}
}
}
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