perf(codegen): pool generated IInvokable request objects

[ReubenBond]

Summary

• Adds instance-scoped, thread-local pooling for generated IInvokable request objects for non-generic grain methods and registers InvokablePool<T> with serializer services.
• Updates source generation and proxies so pooled invokable activators are cached, requests are rented or created via activators, and disposed requests reset their fields and return to their pool.
• Adds message body ownership and disposal handling across send, receive, local-message, one-way, and request/response paths so pooled invokables are not shared or returned too early.
• Includes follow-up fixes for pool isolation, ownership transfer, instance-scoped pools, and preserving synchronous cancellation behavior.

Validation

• git diff --check
• conflict-marker scan
• dotnet build src\Orleans.Serialization\Orleans.Serialization.csproj -m
• dotnet build src\Orleans.CodeGenerator\Orleans.CodeGenerator.csproj -m
• targeted TypeEncodingTests passed on net8/net10; netcoreapp3.1 skipped by xUnit loader

Dependencies / notes

• This PR targets main, but is logically related to message pooling/ref-counting work and may need coordination with that PR.
• Included only InvokablePool/ConcurrentObjectPool ThreadStatic pieces; excluded SEDA, callback pooling, networking rewrite, and benchmarks.

Microsoft Reviewers: Open in CodeFlow

[Copilot]

Pull request overview

This PR introduces pooling for generated IInvokable request objects (primarily for non-generic grain methods) and extends the Orleans runtime messaging pipeline to correctly manage request-body ownership/disposal so pooled invokables are not reused too early.

Changes:

• Added InvokablePool<T> (thread-local, instance-scoped pool) and registered it with serializer services for DI injection into generated activators.
• Updated source generation/proxies/codecs/copiers so invokables are created via cached activators and returned to their pool on Dispose().
• Updated messaging/runtime send/receive/local/one-way/request-response paths to transfer message-body ownership and dispose pooled invokables at the correct time; updated unit tests and generator snapshot baselines.

Show a summary per file

File	Description
test/Orleans.Serialization.UnitTests/InvokablePoolTests.cs	Adds unit tests validating pool instance isolation and safe behavior after disposal.
test/Orleans.CodeGenerator.Tests/snapshots/OrleansSourceGeneratorTests.TestWithUseActivatorAnnotation.verified.cs	Updates expected generated output to include invocation/pooling-related usings.
test/Orleans.CodeGenerator.Tests/snapshots/OrleansSourceGeneratorTests.TestWithSuppressReferenceTrackingAttribute.verified.cs	Updates expected generated output to include invocation/pooling-related usings.
test/Orleans.CodeGenerator.Tests/snapshots/OrleansSourceGeneratorTests.TestWithSerializerTransparentAnnotation.verified.cs	Updates expected generated output to include invocation/pooling-related usings.
test/Orleans.CodeGenerator.Tests/snapshots/OrleansSourceGeneratorTests.TestWithOmitDefaultMemberValuesAnnotation.verified.cs	Updates expected generated output to include invocation/pooling-related usings.
test/Orleans.CodeGenerator.Tests/snapshots/OrleansSourceGeneratorTests.TestRecords.verified.cs	Updates expected generated output to include invocation/pooling-related usings.
test/Orleans.CodeGenerator.Tests/snapshots/OrleansSourceGeneratorTests.TestGrainWithMultipleInterfaces.verified.cs	Updates expected generated grain proxy/invokable output to use activators and return invokables to pools.
test/Orleans.CodeGenerator.Tests/snapshots/OrleansSourceGeneratorTests.TestGrainWithDifferentKeyTypes.verified.cs	Updates expected generated grain proxy/invokable output to use activators and return invokables to pools.
test/Orleans.CodeGenerator.Tests/snapshots/OrleansSourceGeneratorTests.TestGrainMethodAnnotatedWithResponseTimeout.verified.cs	Updates expected generated grain proxy/invokable output to use activators and return invokables to pools.
test/Orleans.CodeGenerator.Tests/snapshots/OrleansSourceGeneratorTests.TestGrainMethodAnnotatedWithInvokableBaseType.verified.cs	Updates expected generated grain proxy/invokable output to use activators and return invokables to pools.
test/Orleans.CodeGenerator.Tests/snapshots/OrleansSourceGeneratorTests.TestGrainComplexGrain.verified.cs	Updates expected generated grain proxy/invokable output to use activators and return invokables to pools.
test/Orleans.CodeGenerator.Tests/snapshots/OrleansSourceGeneratorTests.TestGenericClassWithConstructorParameters.verified.cs	Updates expected generated output to include invocation/pooling-related usings.
test/Orleans.CodeGenerator.Tests/snapshots/OrleansSourceGeneratorTests.TestGenericClass.verified.cs	Updates expected generated output to include invocation/pooling-related usings.
test/Orleans.CodeGenerator.Tests/snapshots/OrleansSourceGeneratorTests.TestCompoundTypeAlias.verified.cs	Updates expected generated output to include invocation/pooling-related usings.
test/Orleans.CodeGenerator.Tests/snapshots/OrleansSourceGeneratorTests.TestClassesWithGeneratedActivatorConstructorAnnotation.verified.cs	Updates expected generated output to include invocation/pooling-related usings.
test/Orleans.CodeGenerator.Tests/snapshots/OrleansSourceGeneratorTests.TestClassWithParameterizedConstructor.verified.cs	Updates expected generated output to include invocation/pooling-related usings.
test/Orleans.CodeGenerator.Tests/snapshots/OrleansSourceGeneratorTests.TestClassWithOptionalConstructorParameters.verified.cs	Updates expected generated output to include invocation/pooling-related usings.
test/Orleans.CodeGenerator.Tests/snapshots/OrleansSourceGeneratorTests.TestClassWithNoPublicConstructors.verified.cs	Updates expected generated output to include invocation/pooling-related usings.
test/Orleans.CodeGenerator.Tests/snapshots/OrleansSourceGeneratorTests.TestClassWithInterfaceConstructorParameter.verified.cs	Updates expected generated output to include invocation/pooling-related usings.
test/Orleans.CodeGenerator.Tests/snapshots/OrleansSourceGeneratorTests.TestClassWithGenerateSerializerAnnotation.verified.cs	Updates expected generated output to include invocation/pooling-related usings.
test/Orleans.CodeGenerator.Tests/snapshots/OrleansSourceGeneratorTests.TestClassWithGenerateMethodSerializersAnnotation.verified.cs	Updates expected generated grain proxy/invokable output to use activators and return invokables to pools.
test/Orleans.CodeGenerator.Tests/snapshots/OrleansSourceGeneratorTests.TestClassReferenceProperties.verified.cs	Updates expected generated output to include invocation/pooling-related usings.
test/Orleans.CodeGenerator.Tests/snapshots/OrleansSourceGeneratorTests.TestClassPrimitiveTypesUsingFullName.verified.cs	Updates expected generated output to include invocation/pooling-related usings.
test/Orleans.CodeGenerator.Tests/snapshots/OrleansSourceGeneratorTests.TestClassPrimitiveTypes.verified.cs	Updates expected generated output to include invocation/pooling-related usings.
test/Orleans.CodeGenerator.Tests/snapshots/OrleansSourceGeneratorTests.TestClassNestedTypes.verified.cs	Updates expected generated output to include invocation/pooling-related usings.
test/Orleans.CodeGenerator.Tests/snapshots/OrleansSourceGeneratorTests.TestBasicStruct.verified.cs	Updates expected generated output to include invocation/pooling-related usings.
test/Orleans.CodeGenerator.Tests/snapshots/OrleansSourceGeneratorTests.TestBasicGrain.verified.cs	Updates expected generated grain proxy/invokable output to use activators and return invokables to pools.
test/Orleans.CodeGenerator.Tests/snapshots/OrleansSourceGeneratorTests.TestBasicClassWithoutNamespace.verified.cs	Updates expected generated output to include invocation/pooling-related usings.
test/Orleans.CodeGenerator.Tests/snapshots/OrleansSourceGeneratorTests.TestBasicClassWithInheritance.verified.cs	Updates expected generated output to include invocation/pooling-related usings.
test/Orleans.CodeGenerator.Tests/snapshots/OrleansSourceGeneratorTests.TestBasicClassWithDifferentAccessModifiers.verified.cs	Updates expected generated output to include invocation/pooling-related usings.
test/Orleans.CodeGenerator.Tests/snapshots/OrleansSourceGeneratorTests.TestBasicClassWithAnnotatedFields.verified.cs	Updates expected generated output to include invocation/pooling-related usings.
test/Orleans.CodeGenerator.Tests/snapshots/OrleansSourceGeneratorTests.TestBasicClass.verified.cs	Updates expected generated output to include invocation/pooling-related usings.
test/Orleans.CodeGenerator.Tests/snapshots/OrleansSourceGeneratorTests.TestAlias.verified.cs	Updates expected generated output to include invocation/pooling-related usings.
src/Orleans.Serialization/Invocation/Pools/InvokablePool.cs	Introduces InvokablePool<T> and keeps the prior static helper for backward compatibility.
src/Orleans.Serialization/Invocation/Pools/ConcurrentObjectPool.cs	Enables nullable annotations and adjusts ThreadLocal usage.
src/Orleans.Serialization/Hosting/ServiceCollectionExtensions.cs	Registers open-generic InvokablePool<> with serializer services.
src/Orleans.Runtime/Messaging/MessageCenter.cs	Copies shared request bodies for local delivery to avoid premature reuse of pooled invokables.
src/Orleans.Runtime/Core/InsideRuntimeClient.cs	Adds explicit request-body ownership transfer and disposal on the receiver side.
src/Orleans.Core/Runtime/InvokableObjectManager.cs	Adds explicit request-body ownership transfer and disposal in the local object manager path.
src/Orleans.Core/Runtime/GrainReferenceRuntime.cs	Ensures requests are disposed at the correct time for request/response vs one-way.
src/Orleans.Core/Networking/Connection.cs	Disposes one-way request bodies after they have been sent.
src/Orleans.Core/Messaging/MessageSerializer.cs	Marks deserialized request/one-way bodies as disposable invokables and not shared.
src/Orleans.Core/Messaging/MessageFactory.cs	Initializes message body ownership/disposal flags and adds a helper to copy body objects.
src/Orleans.Core/Messaging/Message.cs	Adds body ownership/disposal flags plus helper methods to dispose/reset the message body.
src/Orleans.Core.Abstractions/Runtime/GrainReference.cs	Adds cached activator storage on GrainReferenceShared and exposes proxy helpers.
src/Orleans.CodeGenerator/ProxyGenerator.cs	Generates proxies which cache activators and allocate requests via activators where applicable.
src/Orleans.CodeGenerator/LibraryTypes.cs	Adds InvokablePool<> to known library types for generation.
src/Orleans.CodeGenerator/InvokableGenerator.cs	Generates invokables with pool support and emits code to return to pool on Dispose().
src/Orleans.CodeGenerator/CodeGenerator.cs	Adds Orleans.Serialization.Invocation to generated file usings.
src/Orleans.CodeGenerator/ActivatorGenerator.cs	Generates pool-aware activators which rent from InvokablePool<T> before allocating.

Copilot's findings

• Files reviewed: 50/50 changed files
• Comments generated: 9

[Copilot]

Review details

• Files reviewed: 50/50 changed files
• Comments generated: 2
• Review effort level: Lite

[Copilot]

Review details

Suppressed comments (2)

Previously missed (1) — in code that hasn't changed since the last review.

src/Orleans.Runtime/Messaging/MessageCenter.cs:216

• Local request dispatch deep-copies invokable bodies for every loopback request. This adds a full DeepCopier pass (and extra pooled instances) on the hottest path, which may undermine the pooling gains. Since the sender now disposes request bodies when invocation completes, consider transferring ownership by clearing DisposeBodyObject for loopback Request messages instead of copying.

                    if (msg.Direction == Message.Directions.Request && msg.BodyObjectIsShared && msg.BodyObject is { } body)
                    {
                        msg.BodyObject = this.messageFactory.CopyBodyObject(body);
                        msg.DisposeBodyObject = msg.BodyObject is IInvokable;
                        msg.BodyObjectIsShared = false;

src/Orleans.Core/Runtime/CallbackData.cs:55

• SubscribeForCancellation can leak the CancellationTokenRegistration: if the callback completes between the IsCompleted check and assigning _cancellationTokenRegistration, the completion paths will dispose the default registration and this method will store the real registration without disposing it. Store the registration field first, then re-check completion and dispose/reset if already completed.

            if (IsCompleted)
            {
                registration.Dispose();
            }
            else

• Files reviewed: 50/50 changed files
• Comments generated: 2
• Review effort level: Lite

[Copilot]

Review details

Suppressed comments (1)

Previously missed (1) — in code that hasn't changed since the last review.

src/Orleans.Core/Runtime/CallbackData.cs:58

• SubscribeForCancellation has a race where the cancellation token can be canceled after IsCompleted is checked but before _cancellationTokenRegistration is published (or before completion paths dispose it). In that case OnCancellation/OnTimeout/etc will dispose the default registration, then this method stores the real registration and it is never disposed, keeping CallbackData (and the CTS) alive longer than intended.

Consider reinstating a publish/complete state machine (like the previous pending/published flags) or otherwise making publication + disposal coordination atomic (eg, publish the registration, then re-check completion and dispose/clear it in a thread-safe way).

        public void SubscribeForCancellation(CancellationToken cancellationToken)
        {
            if (!cancellationToken.CanBeCanceled)
            {
                return;
            }

            _cancellationToken = cancellationToken;
            var registration = cancellationToken.UnsafeRegister(static arg =>
            {
                var callbackData = (CallbackData)arg!;
                callbackData.OnCancellation();
            }, this);

            if (IsCompleted)
            {
                registration.Dispose();
            }
            else
            {
                _cancellationTokenRegistration = registration;
            }

• Files reviewed: 50/50 changed files
• Comments generated: 0 new
• Review effort level: Lite

[ReubenBond]

The retried .NET CI workflow confirms PR-specific source-generator snapshot mismatches on Windows, Linux, and macOS for both net8.0 and net10.0. Numerous OrleansSourceGeneratorTests produce .received.cs output which differs from the checked-in .verified.cs snapshots, so the generated-output changes and snapshots need to be reconciled. Run: https://github.com/dotnet/orleans/actions/runs/32133814152

[Copilot]

Review details

• Files reviewed: 26/51 changed files
• Comments generated: 1
• Review effort level: Lite

[Copilot]

Review details

Suppressed comments (1)

Previously missed (1) — in code that hasn't changed since the last review.

src/Orleans.Core/Runtime/CallbackData.cs:55

• SubscribeForCancellation has a race where cancellation/completion can occur after the if (IsCompleted) check but before _cancellationTokenRegistration = registration executes. In that case, OnCancellation will dispose the default registration (no-op) and the real registration is never disposed, potentially retaining the callback and leaking the registration.

A simple fix is to publish _cancellationTokenRegistration before the completion check and, if already completed, clear it and dispose the local registration.

            if (IsCompleted)
            {
                registration.Dispose();
            }
            else

• Files reviewed: 26/51 changed files
• Comments generated: 0 new
• Review effort level: Lite

[ReubenBond]

CI root cause: pooling made non-generic generated invokables constructor-injected only, but runtime and test paths still use parameterless reflection activation. That caused matrix-wide BVT failures with \MissingMethodException: No parameterless constructor defined. The branch now emits a compatibility constructor for pooled invokables, keeps pool-aware activation for normal calls, and only returns pool-created instances to the pool. The reproduced durable-jobs BVT passes, generator tests pass on net8.0/net10.0, and \Orleans.slnx\ builds.

[Copilot]

Review details

Suppressed comments (1)

Previously missed (1) — in code that hasn't changed since the last review.

src/Orleans.Core/Runtime/CallbackData.cs:58

• There is a race between the completion check and publishing _cancellationTokenRegistration: if the token is canceled after IsCompleted is read but before _cancellationTokenRegistration is assigned, OnCancellation() will run and dispose the default registration, and the real registration will remain undisposed, keeping this CallbackData instance rooted longer than necessary.

            }
            else
            {
                _cancellationTokenRegistration = registration;
            }

• Files reviewed: 26/51 changed files
• Comments generated: 1
• Review effort level: Lite

[Copilot]

Review details

Suppressed comments (1)

Previously missed (1) — in code that hasn't changed since the last review.

src/Orleans.CodeGenerator/ProxyGenerator.cs:298

• Potential NullReferenceException: AttributeData.AttributeClass can be null (eg, unresolved attribute types during compilation errors). This code dereferences it unconditionally, which can crash the source generator instead of emitting diagnostics.

                if (attr.AttributeClass.GetAttributes(LibraryTypes.InvokeMethodNameAttribute, out var attrs))

• Files reviewed: 26/51 changed files
• Comments generated: 0 new
• Review effort level: Lite

[Copilot]

Review details

• Files reviewed: 37/37 changed files
• Comments generated: 1
• Review effort level: Lite

[Copilot]

Review details

Suppressed comments (1)

src/Orleans.Core/Runtime/GrainReferenceRuntime.cs:164

• Same pooling concern as the generic overload: if RuntimeClient.SendRequest throws before the caller awaits the ValueTask (common for cancellation/disposed paths), the ResponseCompletionSource instance will never have GetResult called and will not be returned to ResponseCompletionSourcePool.

            catch
            {
                DisposeRequest(request);
                throw;
            }

• Files reviewed: 38/38 changed files
• Comments generated: 1
• Review effort level: Lite

[github-actions]

Code coverage

77.60% line coverage - 97,774 / 125,992 lines

Coverage details

• Source files: 1,659
• Scope: every CI test matrix job, including providers, CodeGen, .NET 8/10, Linux, Windows, and macOS
• Sources: maintained repository code under src/ loaded by the complete CI test scope
• Commit: 33f976b2a7
• View the test run and merged coverage artifact
• View the coverage reporting run

[Copilot]

Review details

• Files reviewed: 39/39 changed files
• Comments generated: 0 new
• Review effort level: Lite

[Copilot]

Review details

Suppressed comments (2)

Previously missed (1) — in code that hasn't changed since the last review.

test/Orleans.Serialization.UnitTests/InvokablePoolTests.cs:85

• The test uses unbounded waits/joins (ready.Wait, start.Wait, Thread.Join). If a regression causes a thread to fail before signaling, the test run can hang indefinitely. Add timeouts and assert success so failures surface as test failures instead of deadlocks.

This issue also appears on line 97 of the same file.

test/Orleans.Serialization.UnitTests/InvokablePoolTests.cs:99

• The worker thread blocks on start.Wait() without a timeout. If the main thread never signals (or the event is disposed unexpectedly), the test can hang. Use a timeout and assert to fail fast.

• Files reviewed: 39/39 changed files
• Comments generated: 0 new
• Review effort level: Lite

[Copilot]

Copilot review overview

Review tier: Lite
Findings: 1

New issues introduced by this change (1)

Severity	Finding
	test/​Orleans.Core.Tests/​Runtime/​GrainReferenceRuntimeTests.cs — Unused using directive Microsoft.Extensions.DependencyInjection will produce CS8019 (and may fail…

[Copilot]

Copilot review overview

Review tier: Lite
Findings: 2 · 1

New issues introduced by this change (2)

Severity	Finding
	test/​Orleans.Core.Tests/​Runtime/​GrainReferenceRuntimeTests.cs — Unused using directive will trigger CS8019 (and likely fail the build with TreatWarningsAsErrors).…
	test/​Orleans.Core.Tests/​Messaging/​InvokableMessageOwnershipTests.cs — Unused using directive (System.Buffers) will produce CS8019 and can fail the build when warnings…

Pre-existing issues (1)

Severity	Finding
	test/​Orleans.Core.Tests/​Runtime/​GrainReferenceRuntimeTests.cs — Unused using directive Microsoft.Extensions.DependencyInjection will produce CS8019 (and may fail… View comment

[Copilot]

Copilot review overview

Review tier: Lite
Findings: None

Issues resolved since last review (3)

Severity	Finding
	test/​Orleans.Core.Tests/​Messaging/​InvokableMessageOwnershipTests.cs — Unused using directive (System.Buffers) will produce CS8019 and can fail the build when warnings… View resolved comment
	test/​Orleans.Core.Tests/​Runtime/​GrainReferenceRuntimeTests.cs — Unused using directive will trigger CS8019 (and likely fail the build with TreatWarningsAsErrors).… View resolved comment
	test/​Orleans.Core.Tests/​Runtime/​GrainReferenceRuntimeTests.cs — Unused using directive Microsoft.Extensions.DependencyInjection will produce CS8019 (and may fail… View resolved comment