Remove ParallelExtensionsExtras dependency, replace with SemaphoreSlim

[ispwd]

Which Issue(s) This PR Fixes

Remove obsolete ParallelExtensionsExtras dependency for .NET Core / .NET 5+ compatibility.

Brief Description

Problem:
The ParallelExtensionsExtras NuGet package was originally designed for .NET Framework only and lacks support for .NET Core / .NET 5+. This caused compatibility warnings and prevented the library from being used in modern .NET projects without fallback mode.

Solution:

• Removed the ParallelExtensionsExtras NuGet package dependency entirely
• Replaced LimitedConcurrencyLevelTaskScheduler (from ParallelExtensionsExtras) with native .NET SemaphoreSlim to implement the same concurrency control behavior
• The SemaphoreSlim is initialized with consumptionThreadCount to limit concurrent message consumers, maintaining exactly the same semantic behavior as the original implementation
• No API changes - all public interfaces remain fully backward compatible

Files Changed:

• ConsumeService.cs - Changed from TaskScheduler to SemaphoreSlim for concurrency control
• PushConsumer.cs - Updated field type and initialization
• FifoConsumeService.cs, StandardConsumeService.cs - Updated constructor signatures
• ConsumeServiceTest.cs - Updated tests to match new implementation
• rocketmq-client-csharp.csproj - Removed ParallelExtensionsExtras package reference

How Did You Test This Change?

1. Unit Tests: ✅ All 164 existing unit tests passed

dotnet test
# Passed! - Failed: 0, Passed: 164, Skipped: 0, Total: 164

2. Concurrency Control Verification (Real RocketMQ Server): ✅

• Deployed test against real RocketMQ server (127.0.0.1:8081)
• Configured consumer with consumptionThreadCount = 3
• Sent 20 messages with 200ms simulated consume delay
• Verified max observed concurrent consumers = 3, matching the configured limit
• All 20 messages successfully consumed within expected time
• SemaphoreSlim correctly limits parallelism, matching the original TaskScheduler behavior

3. Backward Compatibility: ✅

• Public API remains unchanged - existing user code requires no modifications
• Same ConsumptionThreadCount configuration option works exactly as before

[github-actions]

This PR is stale because it has been open for 30 days with no activity. It will be closed in 3 days if no further activity occurs. If you wish not to mark it as stale, please leave a comment in this PR.

[oss-sentinel-ai]

Review: Approved ✅

PR: #1244 — Remove ParallelExtensionsExtras dependency, replace with SemaphoreSlim
Type: Compatibility fix (7 files, +49/-52)

Assessment

This PR addresses a legitimate compatibility issue:

• Problem: ParallelExtensionsExtras was designed for .NET Framework only, causing warnings on .NET Core/5+
• Solution: Replace LimitedConcurrencyLevelTaskScheduler with native SemaphoreSlim — a clean, well-supported approach
• Scope: Changes are contained within the C# client module with test updates

Verdict

Good modernization change. Replacing an obsolete dependency with native .NET APIs improves maintainability and compatibility.

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🤖 Automated review by oss-sentinel-ai

[RockteMQ-AI]

Review by github-manager-bot

Summary

Removes the obsolete ParallelExtensionsExtras dependency from the C# client and replaces LimitedConcurrencyTaskScheduler with SemaphoreSlim for concurrency control.

Findings

• [Info] The old TaskScheduler-based approach is replaced with SemaphoreSlim.WaitAsync() + Task.Run(). This is a cleaner pattern for .NET Core / .NET 5+ and removes an unmaintained dependency.
• [Info] The ConsumeService constructor now takes SemaphoreSlim instead of TaskScheduler. Callers are updated accordingly.
• [Info] Error handling is simplified: the TaskCompletionSource wrapper is removed in favor of async/await.
• [Warning] Ensure the SemaphoreSlim is initialized with the correct maxConcurrency value. The old LimitedConcurrencyTaskScheduler had a specific max concurrency; verify the new semaphore matches.
• [Info] The ClientConfig changes propagate the semaphore correctly through the client initialization chain.

Suggestions

• Consider adding a comment explaining why SemaphoreSlim was chosen over other concurrency control mechanisms.
• Verify that the semaphore release happens in a finally block to prevent leaks on exception paths.

Overall: Good modernization. Clean replacement with proper async/await patterns.

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Automated review by github-manager-bot