Modern and efficient C++ Thread Pool Library
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LICENSE initial version Aug 31, 2014 Update Sep 9, 2014
ctpl.h library with dependency on Boost Sep 17, 2014
ctpl_stl.h fixed a bug - crash Jun 12, 2015
example.cpp Update example.cpp Sep 9, 2014


Modern and efficient C++ Thread Pool Library

A thread pool is a programming pattern for parallel execution of jobs,

More specifically, there are some threads dedicated to the pool and a container of jobs. The jobs come to the pool dynamically. A job is fetched and deleted from the container when there is an idle thread. The job is then run on that thread.

A thread pool is helpful when you want to minimize time of loading and destroying threads and when you want to limit the number of parallel jobs that run simultanuasly. For example, time consuming event handlers may be processed in a thread pool to make UI more responsive.


  • standard c++ language, tested to compile on MS Visual Studio 2013 (2012?), gcc 4.8.2 and mingw 4.8.1(with posix threads)
  • simple but effiecient solution, one header only, no need to compile a binary library
  • query the number of idle threads and resize the pool dynamically
  • one API to push to the thread pool any collable object: lambdas, functors, functions, result of bind expression
  • collable objects with variadic number of parameters plus index of the thread running the object
  • automatic template argument deduction
  • get returned value of any type with standard c++ futures
  • get fired exceptions with standard c++ futures
  • use for any purpose under Apache license
  • two variants, one depends on Boost Lockfree Queue library,, which is a header only library

Sample usage

void first(int id) { std::cout << "hello from " << id << '\n'; }

struct Second { void operator()(int id) const { std::cout << "hello from " << id << '\n'; } } second;

void third(int id, const std::string & additional_param) {}

int main () {

ctpl::thread_pool p(2 /* two threads in the pool */);

p.push(first); // function

p.push(third, "additional_param");

p.push( [] (int id){ std::cout << "hello from " << id << '\n'; }); // lambda

p.push(std::ref(second)); // functor, reference

p.push(const_cast<const Second &>(second)); // functor, copy ctor

p.push(std::move(second)); // functor, move ctor