Polly.Contrib.Bulkhead

Bulkhead isolation strategy for Polly v8 resilience pipelines. Limits concurrent executions and queued actions, rejecting excess calls with BulkheadRejectedException.

Polly v8 replaced the v7 BulkheadPolicy with the more general RateLimiter strategy. This package restores the familiar bulkhead semantics — explicit max concurrency and max queue depth — as a first-class Polly v8 resilience strategy.

Install

dotnet add package Polly.Contrib.Bulkhead

Usage

Simple concurrency limit

using Polly.Contrib.Bulkhead;

var pipeline = new ResiliencePipelineBuilder()
    .AddBulkhead(maxConcurrency: 10)
    .Build();

await pipeline.ExecuteAsync(async ct => await CallDownstreamAsync(ct), cancellationToken);

With a queue

var pipeline = new ResiliencePipelineBuilder()
    .AddBulkhead(maxConcurrency: 10, maxQueuedActions: 20)
    .Build();

Calls beyond the 10 concurrent slots queue up. If the queue also fills (>20 waiting), further calls throw BulkheadRejectedException.

Full options

var pipeline = new ResiliencePipelineBuilder()
    .AddBulkhead(new BulkheadStrategyOptions
    {
        MaxConcurrency = 10,
        MaxQueuedActions = 20,
        OnBulkheadRejected = args =>
        {
            logger.LogWarning("Bulkhead rejected call for {Operation}", args.Context.OperationKey);
            return ValueTask.CompletedTask;
        },
    })
    .Build();

Generic pipeline

var pipeline = new ResiliencePipelineBuilder<HttpResponseMessage>()
    .AddBulkhead<HttpResponseMessage>(maxConcurrency: 5)
    .AddRetry(...)
    .Build();

Behaviour

Scenario	Outcome
Slots available	Executes immediately
Slots full, queue not full	Waits in queue
Slots full, queue full	Throws BulkheadRejectedException
No queuing (MaxQueuedActions = 0)	Rejects immediately when at capacity

Composition

Place bulkhead before retry so rejected calls don't get retried:

var pipeline = new ResiliencePipelineBuilder()
    .AddBulkhead(maxConcurrency: 10)  // 1. limit concurrency first
    .AddRetry(...)                     // 2. retry transient failures
    .AddCircuitBreaker(...)            // 3. protect downstream
    .Build();

Support

If Polly.Contrib.Bulkhead helps protect your services, consider supporting the project:

💼 Need .NET resilience help? Visit solidqualitysolutions.com for consulting and architecture services.

Related Packages

Package	Downloads	Description
PollyHealthChecks		ASP.NET Core health checks for Polly v8 circuit breakers — expose circuit-breaker state (Closed, HalfOpen, Open, Isolated) as /health endpoint responses
PollyOpenTelemetry		OpenTelemetry instrumentation for Polly v8 resilience pipelines
PollyBackoff		Backoff delay strategies for Polly v8 resilience pipelines
PollyGrpc		Polly v8 resilience interceptor for gRPC
PollyEFCore		Polly v8 resilience pipelines for Entity Framework Core — wrap every EF Core query and SaveChanges with retry, timeout and circuit-breaker via a single AddPollyResilience() call
PollyRabbitMQ		Polly v8 resilience for RabbitMQ.Client v7+ — retry, circuit-breaker, and timeout for IChannel operations, with built-in RabbitMqTransientErrors predicate covering AlreadyClosedException, BrokerUnreachableException, OperationInterruptedException, and ConnectFailureException
PollyOpenAI		Polly v8 resilience for OpenAI and Azure OpenAI API calls
PollySignalR		Polly v8 reconnect policy for SignalR
PollyMediatR		Polly v8 resilience pipelines for MediatR — add retry, timeout, circuit-breaker, rate-limiting, hedging, and chaos engineering to any MediatR request handler with a single line of DI registration
PollyRedis		Polly v8 resilience for StackExchange.Redis
PollyAzureServiceBus		Polly v8 resilience for Azure Service Bus — retry, circuit breaker, and timeout for sending and receiving messages
PollyKafka		Polly v8 resilience for Confluent.Kafka — retry, circuit breaker, and timeout for producers and consumers
PollyRateLimiter		Convenience extension methods for Polly v8 resilience pipelines: AddFixedWindowRateLimiter, AddSlidingWindowRateLimiter, and AddTokenBucketRateLimiter
PollyCaching		A caching resilience strategy for Polly v8 pipelines
PollyChaos		Chaos engineering and fault-injection resilience strategies for Polly v8 pipelines

Also by the same author

🌐 swevo.github.io

Package	Description
AutoLog.Generator	Compile-time high-performance logging — [Log(Level, Message)] generates LoggerMessage.Define. AOT-safe.
AutoHttpClient.Generator	Compile-time typed HTTP client — [HttpClient] on an interface generates a strongly-typed client. AOT-safe Refit alternative.
AutoDispatch.Generator	Compile-time CQRS dispatcher — [Handler] generates a strongly-typed IDispatcher. MediatR alternative.
AutoWire	Compile-time DI auto-registration — [Scoped]/[Singleton]/[Transient] generates IServiceCollection registration code.
AutoMap.Generator	Compile-time object mapping — [Map(typeof(Dto))] generates ToDto() extension methods. AutoMapper alternative.

License

MIT