fix(pool): fix race condition with small pool sizes

[alitto]

This pull request includes several changes to improve the testing process, optimize concurrency handling, and enhance buffer management. The most important changes include modifying test commands, refining worker pool dispatch logic, and adjusting buffer synchronization mechanisms.

Testing Improvements:

• .github/workflows/main.yml: Updated the Test job to run make test-ci instead of make test for CI-specific test configurations.
• Makefile: Added test-ci target with specific configurations for CI, and adjusted the test target to run tests with a shorter timeout and without counting.

Worker Pool Enhancements:

• pool.go: Introduced PERSISTENT_WORKER_COUNT to ensure a minimum number of workers are always running while the dispatcher is running, added dispatcherRunning mutex to synchronize task dispatching, and refined worker start logic to prevent deadlocks. [1] [2] [3] [4] [5]

Buffer Management Optimization:

• internal/linkedbuffer/linkedbuffer.go: Replaced sync.RWMutex with sync.Mutex for the LinkedBuffer struct to simplify locking mechanisms, and adjusted the Read method to use a single lock for better synchronization. [1] [2]

Minor Code Refinements:

• group_test.go: Simplified the creation of ResultPool and Group instances in tests.
• internal/dispatcher/dispatcher.go: Removed unnecessary reset of the batch slice in the run method.

[codecov]

Codecov Report

Attention: Patch coverage is 97.72727% with 1 line in your changes missing coverage. Please review.

Project coverage is 96.10%. Comparing base (f1d2a44) to head (3880586).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
pool.go	97.61%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #83      +/-   ##
==========================================
+ Coverage   96.00%   96.10%   +0.09%     
==========================================
  Files          14       14              
  Lines         827      847      +20     
==========================================
+ Hits          794      814      +20     
  Misses         30       30              
  Partials        3        3              

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