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[FIX] Rebalancer-compatible Tolerance Rule #9467

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Merged
merged 2 commits into from
Apr 29, 2025
Merged

[FIX] Rebalancer-compatible Tolerance Rule #9467

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c41c332
fix rebalancer compatible rule
ledjon-behluli Apr 28, 2025
210cba0
remove unneccessary comment
ledjon-behluli Apr 28, 2025
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27 changes: 16 additions & 11 deletions src/Orleans.Runtime/Placement/Repartitioning/RebalancerCompatibleRule.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -29,24 +29,15 @@ internal class RebalancerCompatibleRule(IServiceProvider provider) :
private readonly ISiloStatusOracle _oracle = provider.GetRequiredService<ISiloStatusOracle>();
private readonly IActivationRebalancer? _rebalancer = provider.GetService<IActivationRebalancer>();

public bool IsSatisfiedBy(uint imbalance) => imbalance <= _pairwiseImbalance;
public bool IsSatisfiedBy(uint imbalance) => imbalance <= Volatile.Read(ref _pairwiseImbalance);

public void SiloStatusChangeNotification(SiloAddress silo, SiloStatus status)
{
lock (_lock)
{
ref var statusRef = ref CollectionsMarshal.GetValueRefOrAddDefault(_silos, silo, out _);
statusRef = status;

var activeSilos = _silos.Count(s => s.Value == SiloStatus.Active);
var percentageOfBaseline = 100d / (1 + Math.Exp(0.07d * activeSilos - 4.8d));

if (percentageOfBaseline < 10d) percentageOfBaseline = 10d;

var pairwiseImbalance = (uint)Math.Round(10.1d * percentageOfBaseline, 0);
var toleranceFactor = Math.Cos(Math.PI * _clusterImbalance / 2); // This will always be 1 if rebalancer is not registered.

_pairwiseImbalance = (uint)Math.Max(pairwiseImbalance * toleranceFactor, 0);
UpdatePairwiseImbalance();
}
}

Expand All @@ -59,9 +50,23 @@ public void OnReport(RebalancingReport report)
lock (_lock)
{
_clusterImbalance = report.ClusterImbalance;
UpdatePairwiseImbalance();
}
}

private void UpdatePairwiseImbalance()
{
var activeSilos = _silos.Count(s => s.Value == SiloStatus.Active);
var percentageOfBaseline = 100d / (1 + Math.Exp(0.07d * activeSilos - 4.8d));

if (percentageOfBaseline < 10d) percentageOfBaseline = 10d;

var pairwiseImbalance = (uint)Math.Round(10.1d * percentageOfBaseline, 0);
var toleranceFactor = Math.Cos(Math.PI * _clusterImbalance / 2); // This will always be 1 if rebalancer is not registered.

_pairwiseImbalance = (uint)Math.Max(pairwiseImbalance * toleranceFactor, 0);
}

public Task OnStart(CancellationToken cancellationToken)
{
_oracle.SubscribeToSiloStatusEvents(this);
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