Class ThreadPool

Class Documentation

class ThreadPool

High-performance thread pool for parallel file processing.

A thread-safe, efficient thread pool implementation designed specifically for high-throughput file processing tasks. Features dynamic work distribution, resource-aware task scheduling, and cluster-safe operation.

Features

  • Fixed-size thread pool to avoid creation/destruction overhead

  • Task queue with condition variable synchronization

  • Exception-safe task execution with error propagation

  • Graceful shutdown with proper thread joining

  • Memory-efficient task storage using std::function

Characteristics

  • Zero allocation after initialization for task submission

  • Lock-free task completion detection using atomics

  • Optimized for I/O-bound tasks (file reading/parsing)

  • Scales efficiently up to hardware thread limits

Public Functions

explicit ThreadPool(size_t num_threads)

Constructor with thread count specification.

Creates a fixed-size thread pool with the specified number of workers. Threads are created immediately and remain active until destruction.

Note

Recommended thread count is typically between hardware_concurrency/2 and hardware_concurrency for I/O-bound workloads on clusters

Parameters:

num_threads – Number of worker threads to create

~ThreadPool()

Destructor with graceful shutdown.

Stops accepting new tasks, completes all pending tasks, and joins all worker threads. Ensures all resources are properly cleaned up.

template<typename F, typename ...Args>
inline auto enqueue(F &&f, Args&&... args) -> std::future<typename std::invoke_result<F, Args...>::type>

Submit a task for asynchronous execution.

Submits a task to the thread pool for asynchronous execution. The task will be executed by the next available worker thread. Returns a future that can be used to retrieve the result or wait for completion.

Note

This method is thread-safe and can be called concurrently

Template Parameters:

  • F – Function type (automatically deduced)

  • Args – Argument types (automatically deduced)

Parameters:

  • f – Function or callable to execute

  • args – Arguments to pass to the function

Returns:

std::future<return_type> Future for task result

Throws:

std::runtime_error – if pool is shutting down

inline size_t active_count() const

Get number of active (executing) tasks.

Returns the number of tasks currently being executed by worker threads. Useful for monitoring load and determining when processing is complete.

Returns:

Current number of tasks being executed

void wait_for_completion()

Wait for all tasks to complete.

Blocks until all submitted tasks have completed execution. Does not prevent new tasks from being submitted during the wait.

inline bool is_shutting_down() const

Check if thread pool is shutting down.

Returns:

true if shutdown has been initiated