ThreadPool concurrency refactoring (#2220)

[MitchLewis930]

User description

PR_053

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PR Type

Enhancement, Bug fix

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Description

• Wait for threads to enter waiting loop on ThreadPool startup

• Simplify spawn_thread inner threadpool loop and remove continue flag

• Fix concurrency bugs in trim and shutdown logic

• Refactor tests with MutexPool wrapper for better stability

• Add with_mutex helper to handle nested synchronization

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Diagram Walkthrough

flowchart LR
  A["ThreadPool Initialization"] -->|"Wait for threads ready"| B["Startup Synchronization"]
  C["spawn_thread Loop"] -->|"Simplify control flow"| D["Remove continue flag"]
  E["Trim Logic"] -->|"Fix free thread calculation"| F["Better thread management"]
  G["Test Suite"] -->|"Add MutexPool wrapper"| H["Stable concurrent tests"]
  I["Mutex Handling"] -->|"Add with_mutex helper"| J["Handle nested locks"]

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File Walkthrough

	Relevant files
Enhancement	thread_pool.rb Refactor ThreadPool concurrency and synchronization logic lib/puma/thread_pool.rb Wait for threads to enter waiting loop during initialization via @not_full.wait(@mutex) Simplify spawn_thread by removing continue flag and handling thread exit directly Move thread cleanup (decrement @spawned, delete from @workers) into trim logic Add with_mutex helper method to handle nested synchronization safely Fix trim logic to calculate free threads as @waiting - @todo.size Update shutdown to set @trim_requested = @spawned for proper cleanup +24/-27
Tests	test_thread_pool.rb Refactor tests with MutexPool for better stability              test/test_thread_pool.rb Create MutexPool wrapper class to synchronize work execution for deterministic tests Simplify test setup by removing manual mutex/condition variable management Replace sleep-based synchronization with @not_full.wait in MutexPool Add test_waiting_on_startup to verify threads wait on initialization Add test_thread_name as separate test for thread naming Remove skip_on directives and pause calls by using MutexPool synchronization Simplify test assertions and remove race condition workarounds +94/-120
Documentation	History.md Update changelog with ThreadPool improvements                        History.md Add entry for fixed concurrency bugs in ThreadPool affecting non-GVL Rubies Add entry for ThreadPool concurrency refactoring in Refactor section +2/-0

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[qodo-code-review]

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🟢	No security concerns identified No security vulnerabilities detected by AI analysis. Human verification advised for critical code.
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🟢	Generic: Comprehensive Audit Trails Objective: To create a detailed and reliable record of critical system actions for security analysis and compliance. Status: Passed Learn more about managing compliance generic rules or creating your own custom rules
	Generic: Meaningful Naming and Self-Documenting Code Objective: Ensure all identifiers clearly express their purpose and intent, making code self-documenting Status: Passed Learn more about managing compliance generic rules or creating your own custom rules
	Generic: Secure Error Handling Objective: To prevent the leakage of sensitive system information through error messages while providing sufficient detail for internal debugging. Status: Passed Learn more about managing compliance generic rules or creating your own custom rules
	Generic: Secure Logging Practices Objective: To ensure logs are useful for debugging and auditing without exposing sensitive information like PII, PHI, or cardholder data. Status: Passed Learn more about managing compliance generic rules or creating your own custom rules
	Generic: Security-First Input Validation and Data Handling Objective: Ensure all data inputs are validated, sanitized, and handled securely to prevent vulnerabilities Status: Passed Learn more about managing compliance generic rules or creating your own custom rules
⚪	Generic: Robust Error Handling and Edge Case Management Objective: Ensure comprehensive error handling that provides meaningful context and graceful degradation Status: Unbounded wait risk: The new MutexPool#<< test helper waits on @not_full without a timeout, which can hang tests indefinitely if the signal is missed or the worker never reaches the waiting state. Referred Code def <<(work, &block) work = [work] unless work.is_a?(Array) with_mutex do work.each {|arg| super arg} yield if block_given? @not_full.wait(@mutex) end end Learn more about managing compliance generic rules or creating your own custom rules

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[qodo-code-review]

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