Package io.grpc.xds

Class WeightedRoundRobinLoadBalancer

java.lang.Object

io.grpc.LoadBalancer

io.grpc.util.MultiChildLoadBalancer

io.grpc.xds.WeightedRoundRobinLoadBalancer

final class WeightedRoundRobinLoadBalancer
extends io.grpc.util.MultiChildLoadBalancer

A LoadBalancer that provides weighted-round-robin load-balancing over the EquivalentAddressGroups from the NameResolver. The subchannel weights are determined by backend metrics using ORCA. To use WRR, users may configure through channel serviceConfig. Example config:

 
       String wrrConfig = "{\"loadBalancingConfig\":" +
           "[{\"weighted_round_robin\":{\"enableOobLoadReport\":true, " +
           "\"blackoutPeriod\":\"10s\"," +
           "\"oobReportingPeriod\":\"10s\"," +
           "\"weightExpirationPeriod\":\"180s\"," +
           "\"errorUtilizationPenalty\":\"1.0\"," +
           "\"weightUpdatePeriod\":\"1s\"}}]}";
        serviceConfig = (Map<String, ?>) JsonParser.parse(wrrConfig);
        channel = ManagedChannelBuilder.forTarget("test:///lb.test.grpc.io")
            .defaultServiceConfig(serviceConfig)
            .build();
  
  

Users may also configure through xDS control plane via custom lb policy. But that is much more complex to set up. Example config:

  localityLbPolicies:
   - customPolicy:
       name: weighted_round_robin
       data: '{ "enableOobLoadReport": true }'
  

See related documentation: https://cloud.google.com/service-mesh/legacy/load-balancing-apis/proxyless-configure-advanced-traffic-management#custom-lb-config

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
(package private) static final class	WeightedRoundRobinLoadBalancer.StaticStrideScheduler
private final class	WeightedRoundRobinLoadBalancer.UpdateWeightTask
(package private) final class	WeightedRoundRobinLoadBalancer.WeightedChildLbState
(package private) static final class	WeightedRoundRobinLoadBalancer.WeightedRoundRobinLoadBalancerConfig
(package private) static final class	WeightedRoundRobinLoadBalancer.WeightedRoundRobinPicker
(package private) final class	WeightedRoundRobinLoadBalancer.WrrSubchannel

Nested classes/interfaces inherited from class io.grpc.util.MultiChildLoadBalancer

io.grpc.util.MultiChildLoadBalancer.AcceptResolvedAddrRetVal, io.grpc.util.MultiChildLoadBalancer.ChildLbState, io.grpc.util.MultiChildLoadBalancer.Endpoint

Nested classes/interfaces inherited from class io.grpc.LoadBalancer

io.grpc.LoadBalancer.CreateSubchannelArgs, io.grpc.LoadBalancer.ErrorPicker, io.grpc.LoadBalancer.Factory, io.grpc.LoadBalancer.FixedResultPicker, io.grpc.LoadBalancer.Helper, io.grpc.LoadBalancer.PickDetailsConsumer, io.grpc.LoadBalancer.PickResult, io.grpc.LoadBalancer.PickSubchannelArgs, io.grpc.LoadBalancer.ResolvedAddresses, io.grpc.LoadBalancer.Subchannel, io.grpc.LoadBalancer.SubchannelPicker, io.grpc.LoadBalancer.SubchannelStateListener

Field Summary

Fields

Modifier and Type	Field	Description
private WeightedRoundRobinLoadBalancer.WeightedRoundRobinLoadBalancerConfig	config
private io.grpc.LoadBalancer.SubchannelPicker	currentPicker
private static final io.grpc.LongCounterMetricInstrument	ENDPOINT_WEIGHT_NOT_YET_USEABLE_COUNTER
private static final io.grpc.LongCounterMetricInstrument	ENDPOINT_WEIGHT_STALE_COUNTER
private static final io.grpc.DoubleHistogramMetricInstrument	ENDPOINT_WEIGHTS_HISTOGRAM
private final long	infTime
private String	locality
private static final Logger	log
private static final io.grpc.LongCounterMetricInstrument	RR_FALLBACK_COUNTER
private final AtomicInteger	sequence
private final io.grpc.SynchronizationContext	syncContext
private final io.grpc.Deadline.Ticker	ticker
private final ScheduledExecutorService	timeService
private final Runnable	updateWeightTask
private io.grpc.SynchronizationContext.ScheduledHandle	weightUpdateTimer

Fields inherited from class io.grpc.util.MultiChildLoadBalancer

currentConnectivityState, pickFirstLbProvider, resolvingAddresses

Fields inherited from class io.grpc.LoadBalancer

ATTR_HEALTH_CHECKING_CONFIG, DISABLE_SUBCHANNEL_RECONNECT_KEY, EMPTY_PICKER, HAS_HEALTH_PRODUCER_LISTENER_KEY, HEALTH_CONSUMER_LISTENER_ARG_KEY, IS_PETIOLE_POLICY

Constructor Summary

Constructors

Constructor	Description
WeightedRoundRobinLoadBalancer(io.grpc.LoadBalancer.Helper helper, io.grpc.Deadline.Ticker ticker)
WeightedRoundRobinLoadBalancer(io.grpc.LoadBalancer.Helper helper, io.grpc.Deadline.Ticker ticker, Random random)

Method Summary

Modifier and Type	Method	Description
io.grpc.Status	acceptResolvedAddresses(io.grpc.LoadBalancer.ResolvedAddresses resolvedAddresses)
private void	createAndApplyOrcaListeners()
protected io.grpc.util.MultiChildLoadBalancer.ChildLbState	createChildLbState(Object key)
private io.grpc.LoadBalancer.SubchannelPicker	createReadyPicker(Collection<io.grpc.util.MultiChildLoadBalancer.ChildLbState> activeList)
void	shutdown()
private void	updateBalancingState(io.grpc.ConnectivityState state, io.grpc.LoadBalancer.SubchannelPicker picker)
protected void	updateOverallBalancingState()	Updates picker with the list of active subchannels (state == READY).
private void	updateWeight(WeightedRoundRobinLoadBalancer.WeightedRoundRobinPicker picker)

Methods inherited from class io.grpc.util.MultiChildLoadBalancer

acceptResolvedAddressesInternal, aggregateState, createChildAddressesMap, getChildLbState, getChildLbStateEag, getChildLbStates, getHelper, getReadyChildren, handleNameResolutionError, shutdownRemoved

Methods inherited from class io.grpc.LoadBalancer

canHandleEmptyAddressListFromNameResolution, handleResolvedAddresses, handleSubchannelState, requestConnection

Methods inherited from class java.lang.Object

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

Field Details

RR_FALLBACK_COUNTER

private static final io.grpc.LongCounterMetricInstrument RR_FALLBACK_COUNTER

ENDPOINT_WEIGHT_NOT_YET_USEABLE_COUNTER

private static final io.grpc.LongCounterMetricInstrument ENDPOINT_WEIGHT_NOT_YET_USEABLE_COUNTER

ENDPOINT_WEIGHT_STALE_COUNTER

private static final io.grpc.LongCounterMetricInstrument ENDPOINT_WEIGHT_STALE_COUNTER

ENDPOINT_WEIGHTS_HISTOGRAM

private static final io.grpc.DoubleHistogramMetricInstrument ENDPOINT_WEIGHTS_HISTOGRAM

log

private static final Logger log

config

private WeightedRoundRobinLoadBalancer.WeightedRoundRobinLoadBalancerConfig config

syncContext

private final io.grpc.SynchronizationContext syncContext

timeService

private final ScheduledExecutorService timeService

weightUpdateTimer

private io.grpc.SynchronizationContext.ScheduledHandle weightUpdateTimer

updateWeightTask

private final Runnable updateWeightTask

sequence

private final AtomicInteger sequence

infTime

private final long infTime

ticker

private final io.grpc.Deadline.Ticker ticker

locality

private String locality

currentPicker

private io.grpc.LoadBalancer.SubchannelPicker currentPicker

Constructor Details

WeightedRoundRobinLoadBalancer

public WeightedRoundRobinLoadBalancer(io.grpc.LoadBalancer.Helper helper,
 io.grpc.Deadline.Ticker ticker)

WeightedRoundRobinLoadBalancer

WeightedRoundRobinLoadBalancer(io.grpc.LoadBalancer.Helper helper,
 io.grpc.Deadline.Ticker ticker,
 Random random)

Method Details

createChildLbState

protected io.grpc.util.MultiChildLoadBalancer.ChildLbState createChildLbState(Object key)

Overrides:

createChildLbState in class io.grpc.util.MultiChildLoadBalancer

acceptResolvedAddresses

public io.grpc.Status acceptResolvedAddresses(io.grpc.LoadBalancer.ResolvedAddresses resolvedAddresses)

Overrides:

acceptResolvedAddresses in class io.grpc.util.MultiChildLoadBalancer

updateOverallBalancingState

protected void updateOverallBalancingState()

Updates picker with the list of active subchannels (state == READY).

Specified by:

updateOverallBalancingState in class io.grpc.util.MultiChildLoadBalancer

createReadyPicker

private io.grpc.LoadBalancer.SubchannelPicker createReadyPicker(Collection<io.grpc.util.MultiChildLoadBalancer.ChildLbState> activeList)

updateWeight

private void updateWeight(WeightedRoundRobinLoadBalancer.WeightedRoundRobinPicker picker)

updateBalancingState

private void updateBalancingState(io.grpc.ConnectivityState state,
 io.grpc.LoadBalancer.SubchannelPicker picker)

createAndApplyOrcaListeners

private void createAndApplyOrcaListeners()

shutdown

public void shutdown()

Overrides:

shutdown in class io.grpc.util.MultiChildLoadBalancer