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* the Apache License, Version 2.0 (the "License"); you may
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* 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.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;
import org.elasticsearch.node.settings.NodeSettingsService;
/**
* {@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 String NAME = "throttling";
public static final String CLUSTER_ROUTING_ALLOCATION_NODE_INITIAL_PRIMARIES_RECOVERIES = "cluster.routing.allocation.node_initial_primaries_recoveries";
public static final String CLUSTER_ROUTING_ALLOCATION_NODE_CONCURRENT_RECOVERIES = "cluster.routing.allocation.node_concurrent_recoveries";
public static final String CLUSTER_ROUTING_ALLOCATION_CONCURRENT_RECOVERIES = "cluster.routing.allocation.concurrent_recoveries";
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;
private volatile int primariesInitialRecoveries;
private volatile int concurrentRecoveries;
@Inject
public ThrottlingAllocationDecider(Settings settings, NodeSettingsService nodeSettingsService) {
super(settings);
this.primariesInitialRecoveries = settings.getAsInt(CLUSTER_ROUTING_ALLOCATION_NODE_INITIAL_PRIMARIES_RECOVERIES, DEFAULT_CLUSTER_ROUTING_ALLOCATION_NODE_INITIAL_PRIMARIES_RECOVERIES);
this.concurrentRecoveries = settings.getAsInt(CLUSTER_ROUTING_ALLOCATION_CONCURRENT_RECOVERIES, settings.getAsInt(CLUSTER_ROUTING_ALLOCATION_NODE_CONCURRENT_RECOVERIES, DEFAULT_CLUSTER_ROUTING_ALLOCATION_NODE_CONCURRENT_RECOVERIES));
logger.debug("using node_concurrent_recoveries [{}], node_initial_primaries_recoveries [{}]", concurrentRecoveries, primariesInitialRecoveries);
nodeSettingsService.addListener(new ApplySettings());
}
@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);
}
}
class ApplySettings implements NodeSettingsService.Listener {
@Override
public void onRefreshSettings(Settings settings) {
int primariesInitialRecoveries = settings.getAsInt(CLUSTER_ROUTING_ALLOCATION_NODE_INITIAL_PRIMARIES_RECOVERIES, ThrottlingAllocationDecider.this.primariesInitialRecoveries);
if (primariesInitialRecoveries != ThrottlingAllocationDecider.this.primariesInitialRecoveries) {
logger.info("updating [cluster.routing.allocation.node_initial_primaries_recoveries] from [{}] to [{}]", ThrottlingAllocationDecider.this.primariesInitialRecoveries, primariesInitialRecoveries);
ThrottlingAllocationDecider.this.primariesInitialRecoveries = primariesInitialRecoveries;
}
int concurrentRecoveries = settings.getAsInt(CLUSTER_ROUTING_ALLOCATION_NODE_CONCURRENT_RECOVERIES, ThrottlingAllocationDecider.this.concurrentRecoveries);
if (concurrentRecoveries != ThrottlingAllocationDecider.this.concurrentRecoveries) {
logger.info("updating [cluster.routing.allocation.node_concurrent_recoveries] from [{}] to [{}]", ThrottlingAllocationDecider.this.concurrentRecoveries, concurrentRecoveries);
ThrottlingAllocationDecider.this.concurrentRecoveries = concurrentRecoveries;
}
}
}
}