When I run my code :
nb workers = 12 I'm i : 0 HELLO I'm func1 BYE I'm func2 terminate called after throwing an instance of 'std::system_error' what(): Invalid argument Aborted (core dumped) terminate called after throwing an instance of 'std::system_error'l
what(): Invalid argument
#ifndef CPP_PLAZZA_EXAMPLE_H #define CPP_PLAZZA_EXAMPLE_H #include <thread> #include <vector> #include <list> #include <memory> #include <functional> #include <mutex> #include <condition_variable> #include <atomic> #include <iterator> #include <tuple> class ThreadPool { public: ThreadPool(size_t numThreads); virtual ~ThreadPool(); void executeJob(std::function<void()> job, std::function<void()> notificationJob); void wait_for_done(); private: void loop(); std::pair<std::function<void()>, std::function<void()> > getNextJob(); std::vector<std::thread> m_workers; std::list<std::pair<std::function<void()>, std::function<void()> > > m_jobs; std::mutex m_lockJobsList; std::condition_variable m_notifyJob; std::atomic<bool> m_bTerminate; class Terminated: public std::runtime_error { public: Terminated(const std::string& what): std::runtime_error(what) {} }; }; #endif //CPP_PLAZZA_EXAMPLE_H and here it is my .cpp
#include <iostream> #include "example.h" ThreadPool::ThreadPool(size_t numThreads): m_workers(numThreads), m_bTerminate(false) { m_workers.reserve(numThreads); for (size_t i = 0; i < numThreads; i++) { this->m_workers.emplace_back(&ThreadPool::loop, this); } /*for (std::vector<std::thread>::iterator it = this->m_workers.begin(); it != this->m_workers.end(); it++) assert(std::next(it, 1) ==);*/ } ThreadPool::~ThreadPool() { { std::unique_lock<std::mutex> lockList(m_lockJobsList); m_bTerminate = true; m_notifyJob.notify_all(); } /* for(std::vector<std::thread>::iterator it = m_workers.begin(); it != m_workers.end(); it++) { it->join(); }*/ std::this_thread::sleep_for(std::chrono::seconds(5)); } void ThreadPool::executeJob(std::function<void()> job, std::function<void()> notificationJob) { std::unique_lock<std::mutex> lockList(m_lockJobsList); m_jobs.emplace_back(std::pair<std::function<void()>, std::function<void()> >(std::move(job), std::move(notificationJob))); std::cout << m_jobs.size() << std::endl; m_notifyJob.notify_one(); } std::pair<std::function<void()>, std::function<void()> > ThreadPool::getNextJob() { std::unique_lock<std::mutex> lockList(m_lockJobsList); while(!m_bTerminate) { if(!m_jobs.empty()) { std::pair<std::function<void()>, std::function<void()>> job = std::ref(m_jobs.front()); m_jobs.pop_front(); return job; } m_notifyJob.wait(lockList); } throw Terminated("Thread terminated"); } void func1() { std::cout << "HELLO I'm func1" << std::endl; } void ThreadPool::loop() { try { for(;;) { std::pair<std::function<void()>, std::function<void()> > job = getNextJob(); job.first(); job.second(); } } catch(Terminated& e) { } } void func2() { std::cout << "BYE I'm func2" << std::endl; } void ThreadPool::wait_for_done() { std::cout << "nb workers = " << this->m_workers.size() << std::endl; int i = 0; for(std::vector<std::thread>::iterator it = m_workers.begin(); it != m_workers.end(); ++it) { std::cout << "je suis i : " << i << std::endl; i++; (*it).join(); } } int main() { ThreadPool pool(6); pool.executeJob(func1, func2); pool.wait_for_done(); } I think that my error is I join several time on one thread but how to fix it ?
Compilation line :
g++ -Wall -Werror -W -Wextra example.cpp -pthread -std=c++11 I tried joinable before join like this (in wait for done) :
for(std::vector<std::thread>::iterator it = m_workers.begin(); it != m_workers.end(); ++it) { if ((*it).joinable()) (*it).join(); } And I had an infinite loop