com.netflix.loadbalancer

Class ZoneAwareLoadBalancer<T extends Server>

java.lang.Object

com.netflix.loadbalancer.AbstractLoadBalancer

com.netflix.loadbalancer.BaseLoadBalancer

com.netflix.loadbalancer.DynamicServerListLoadBalancer<T>

com.netflix.loadbalancer.ZoneAwareLoadBalancer<T>

Type Parameters:

T -

All Implemented Interfaces:

com.netflix.client.IClientConfigAware, PrimeConnections.PrimeConnectionListener, ILoadBalancer

public class ZoneAwareLoadBalancer<T extends Server>
extends DynamicServerListLoadBalancer<T>

Load balancer that can avoid a zone as a whole when choosing server.

The key metric used to measure the zone condition is Average Active Requests, which is aggregated per rest client per zone. It is the total outstanding requests in a zone divided by number of available targeted instances (excluding circuit breaker tripped instances). This metric is very effective when timeout occurs slowly on a bad zone.

The LoadBalancer will calculate and examine zone stats of all available zones. If the Average Active Requests for any zone has reached a configured threshold, this zone will be dropped from the active server list. In case more than one zone has reached the threshold, the zone with the most active requests per server will be dropped. Once the the worst zone is dropped, a zone will be chosen among the rest with the probability proportional to its number of instances. A server will be returned from the chosen zone with a given Rule (A Rule is a load balancing strategy, for example AvailabilityFilteringRule) For each request, the steps above will be repeated. That is to say, each zone related load balancing decisions are made at real time with the up-to-date statistics aiding the choice.

Nested Class Summary

Nested classes/interfaces inherited from class com.netflix.loadbalancer.AbstractLoadBalancer

AbstractLoadBalancer.ServerGroup

Field Summary

Fields inherited from class com.netflix.loadbalancer.DynamicServerListLoadBalancer

serverListUpdateInProgress, serverRefreshEnabled

Fields inherited from class com.netflix.loadbalancer.BaseLoadBalancer

allServerList, allServerLock, lbStats, lbTimer, maxTotalPingTimeSeconds, name, ping, pingInProgress, pingIntervalSeconds, rule, serverComparator, upServerList, upServerLock

Constructor Summary

Constructors

Constructor and Description
ZoneAwareLoadBalancer()
ZoneAwareLoadBalancer(com.netflix.client.config.IClientConfig niwsClientConfig)
ZoneAwareLoadBalancer(com.netflix.client.config.IClientConfig clientConfig, IRule rule, IPing ping, ServerList<T> serverList, ServerListFilter<T> filter)

Method Summary

Methods

Modifier and Type	Method and Description
Server	chooseServer(java.lang.Object key) Choose a server from load balancer.
void	setRule(IRule rule)
protected void	setServerListForZones(java.util.Map<java.lang.String,java.util.List<Server>> zoneServersMap)

Methods inherited from class com.netflix.loadbalancer.DynamicServerListLoadBalancer

enableAndInitLearnNewServersFeature, forceQuickPing, getCoreThreads, getFilter, getLastUpdate, getNumberMissedCycles, getServerListImpl, initWithNiwsConfig, setFilter, setPing, setServerListImpl, setServersList, shutdown, stopServerListRefreshing, toString, updateAllServerList, updateListOfServers

Methods inherited from class com.netflix.loadbalancer.BaseLoadBalancer

addServer, addServerListChangeListener, addServers, cancelPingTask, choose, getClientConfig, getLoadBalancerStats, getMaxTotalPingTime, getName, getPing, getPingInterval, getPrimeConnections, getRule, getServerByIndex, getServerCount, getServerList, getServerList, init, isEnablePrimingConnections, isPingInProgress, lockAllServerList, lockUpServerList, markServerDown, markServerDown, primeCompleted, removeServerListChangeListener, setEnablePrimingConnections, setLoadBalancerStats, setMaxTotalPingTime, setPingInterval, setPrimeConnections

Methods inherited from class com.netflix.loadbalancer.AbstractLoadBalancer

chooseServer

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

ZoneAwareLoadBalancer

public ZoneAwareLoadBalancer()

ZoneAwareLoadBalancer

public ZoneAwareLoadBalancer(com.netflix.client.config.IClientConfig clientConfig,
                     IRule rule,
                     IPing ping,
                     ServerList<T> serverList,
                     ServerListFilter<T> filter)

ZoneAwareLoadBalancer

public ZoneAwareLoadBalancer(com.netflix.client.config.IClientConfig niwsClientConfig)

Method Detail

setServerListForZones

protected void setServerListForZones(java.util.Map<java.lang.String,java.util.List<Server>> zoneServersMap)

Overrides:

setServerListForZones in class DynamicServerListLoadBalancer<T extends Server>

chooseServer

public Server chooseServer(java.lang.Object key)

Description copied from interface: ILoadBalancer

Choose a server from load balancer.

Specified by:

chooseServer in interface ILoadBalancer

Overrides:

chooseServer in class BaseLoadBalancer

Parameters:

key - An object that the load balancer may use to determine which server to return. null if the load balancer does not use this parameter.

Returns:

server chosen

setRule

public void setRule(IRule rule)

Overrides:

setRule in class BaseLoadBalancer