我一直在研究boost::fibers作为一种解决我的数据处理和IO问题的方法。 shared_work调度程序看起来很有希望，因为它可以让我为每个数据处理源启动一个数据处理任务，然后让它们根据需要在几个线程之间相互分配。
但是，这使我想到了问题的根源：看来每个进程只能有一个shared_work'pool'。如果我要在一组处理线程中共享12个光纤，而在4个线程之间共享数据，同时又有另一组12条光纤将处理后的数据写入到在另外4个线程之间共享的文件，该怎么办？
类似的东西：
#include<string>
#include<iostream>
#include<vector>
#include<mutex>
#include<thread>
#include<random>
#include<map>
#include<sstream>
#include<boost/bind.hpp>
#include<boost/fiber/all.hpp>
typedef boost::fibers::fiber FiberType;
typedef std::unique_lock<boost::fibers::mutex> LockType;
static const int fiberIterationCount = 5000;
static const int fiberCount = 12;
static const int threadCount = 4;
static const int distLowerLimit = 50;
static const int distUpperLimit = 500;
static boost::fibers::mutex firstMutex{};
static boost::fibers::mutex secondMutex{};
static boost::fibers::condition_variable firstCondition{};
static boost::fibers::condition_variable secondCondition{};
static boost::fibers::barrier synchronize{2*threadCount};
static int typeOneFibersFinished{0};
static int typeTwoFibersFinished{0};
static std::mt19937 typeOneGenerators[fiberCount];
static std::mt19937 typeTwoGenerators[fiberCount];
static std::mutex typeMapMutex;//lock for writing unnecessary for reads
static std::map<std::thread::id, std::string> threadTypeMap;
//simple function to give a heavy cpu load of variable duration
unsigned long long findPrimeNumber(int n)
{
int count=0;
unsigned long long a = 2;
while(count<n)
{
bool isPrime = true;
for(unsigned long long b = 2; (b * b) <= a; ++b)
{
if((a % b) == 0)
{
isPrime = false;
break;
}
}
if(isPrime)
{
count++;
}
++a;
}
return (a - 1);
}
void fiberTypeOne(int fiberNumber)
{
std::cout<<"Starting Type One Fiber #"<<fiberNumber;
std::uniform_int_distribution<int> dist(distLowerLimit, distUpperLimit);
for(int i=0; i<fiberIterationCount; ++i)
{
//generate a randomish load on this fiber so that it does not take a regular time slice
int tempPrime = dist(typeOneGenerators[fiberNumber]);
unsigned long long temp = findPrimeNumber(tempPrime);
std::cout << "T1 fiber #"<<fiberNumber<<" running on "<<threadTypeMap[std::this_thread::get_id()]
<<"\n Generated: "<<tempPrime<<", "<<temp;
boost::this_fiber::yield();
}
{
LockType lock(firstMutex);
++typeOneFibersFinished;
}
firstCondition.notify_all();
}
void threadTypeOne(int threadNumber)
{
//make a shared work scheduler that associates its fibers with "fiber pool 0"
boost::fibers::use_scheduling_algorithm< multi_pool_scheduler<0> >();
std::cout<<"Starting Type One Thread #"<<threadNumber<<" With Thread ID: "<<std::this_thread::get_id();
{
std::unique_lock<std::mutex> lock{typeMapMutex};
std::ostringstream gen;
gen<<"Thread Type 1 - Number: "<<threadNumber<<" with id: "<<std::this_thread::get_id();
threadTypeMap[std::this_thread::get_id()] = gen.str();
}
if(threadNumber == 0)
{ //if we are thread zero, create the fibers then join them to take ourselves off the "fiber list"
std::cout<<"Spawning Type One Fibers";
for(int fiberNumber=0; fiberNumber<fiberCount; ++fiberNumber)
{//create the fibers and instantly detach them
FiberType(boost::bind(&fiberTypeOne, fiberNumber)).detach();
}
}
synchronize.wait();
std::cout<<"T1 Thread preparing to wait";
//now let the fibers do their thing
LockType lock(firstMutex);
firstCondition.wait(lock, [](){return (typeOneFibersFinished == fiberCount);});
}
void fiberTypeTwo(int fiberNumber)
{
std::cout<<"Starting Type Two Fiber #"<<fiberNumber;
std::uniform_int_distribution<int> dist(distLowerLimit, distUpperLimit);
for(int i=0; i<fiberIterationCount; ++i)
{
//generate a randomish load on this fiber so that it does not take a regular time slice
int tempPrime = dist(typeTwoGenerators[fiberNumber]);
unsigned long long temp = findPrimeNumber(tempPrime);
std::cout << "T2 fiber #"<<fiberNumber<<" running on "<<threadTypeMap[std::this_thread::get_id()]
<<"\n Generated: "<<tempPrime<<", "<<temp;
boost::this_fiber::yield();
}
{
LockType lock(secondMutex);
++typeTwoFibersFinished;
}
secondCondition.notify_all();
}
void threadTypeTwo(int threadNumber)
{
//make a shared work scheduler that associates its fibers with "fiber pool 1"
boost::fibers::use_scheduling_algorithm< multi_pool_scheduler<1> >();
std::cout<<"Starting Type Two Thread #"<<threadNumber<<" With Thread ID: "<<std::this_thread::get_id();
{
std::unique_lock<std::mutex> lock{typeMapMutex};
std::ostringstream gen;
gen<<"Thread Type 2 - Number: "<<threadNumber<<" with id: "<<std::this_thread::get_id();
threadTypeMap[std::this_thread::get_id()] = gen.str();
}
if(threadNumber == 0)
{ //if we are thread zero, create the fibers then join them to take ourselves off the "fiber list"
std::cout<<"Spawning Type Two Fibers";
for(int fiberNumber=0; fiberNumber<fiberCount; ++fiberNumber)
{//create the fibers and instantly detach them
FiberType(boost::bind(&fiberTypeTwo, fiberNumber)).detach();
}
}
synchronize.wait();
std::cout<<"T2 Thread preparing to wait";
//now let the fibers do their thing
LockType lock(secondMutex);
secondCondition.wait(lock, [](){return (typeTwoFibersFinished == fiberCount);});
}
int main(int argc, char* argv[])
{
std::cout<<"Initializing Random Number Generators";
for(unsigned i=0; i<fiberCount; ++i)
{
typeOneGenerators->seed(i*500U - 1U);
typeTwoGenerators->seed(i*1500U - 1U);
}
std::cout<<"Commencing Main Thread Startup Startup";
std::vector<std::thread> typeOneThreads;
std::vector<std::thread> typeTwoThreads;
for(int i=0; i<threadCount; ++i)
{
typeOneThreads.emplace_back(std::thread(boost::bind(&threadTypeOne, i)));
typeTwoThreads.emplace_back(std::thread(boost::bind(&threadTypeTwo, i)));
}
//now let the threads do their thing and wait for them to finish with join
for(unsigned i=0; i<threadCount; ++i)
{
typeOneThreads[i].join();
}
for(unsigned i=0; i<threadCount; ++i)
{
typeTwoThreads[i].join();
}
std::cout<<"Shutting Down";
return 0;
}
是否可以在不编写自己的光纤调度程序的情况下实现？如果可以，怎么办？
答案 0 :(得分：1)
我确定确实需要编写自己的调度程序。但是，实际工作量很少。 boost::fibers::shared_work调度程序使用单个静态队列（由静态互斥体保护）管理线程之间共享的光纤列表。还有另一个队列控制着每个线程的主光纤（因为每个线程都有自己的调度程序），但这是类实例的本地队列，而不是静态成员在类的所有实例之间共享的队列。
然后，为了防止静态队列和锁在单独的线程集之间共享，解决方案是在类的前面放置一个模板参数（通常是无用的）。然后，每个线程将不同的参数传递给该模板。通过这种方式，由于模板的每种特殊化都会获得不同的对象，因此对于每个实例，具有不同的池号都会获得不同的静态变量集。
下面是我对该解决方案的实现（主要是boost::fiber::shared_work的副本，其中更清楚地命名了一些变量和类型，并添加了模板参数）。
#include <condition_variable>
#include <chrono>
#include <deque>
#include <mutex>
#include <boost/config.hpp>
#include <boost/fiber/algo/algorithm.hpp>
#include <boost/fiber/context.hpp>
#include <boost/fiber/detail/config.hpp>
#include <boost/fiber/scheduler.hpp>
#include <boost/assert.hpp>
#include "boost/fiber/type.hpp"
#ifdef BOOST_HAS_ABI_HEADERS
# include BOOST_ABI_PREFIX
#endif
#ifdef _MSC_VER
# pragma warning(push)
# pragma warning(disable:4251)
#endif
/*!
* @class SharedWorkPool
* @brief A scheduler for boost::fibers that operates in a manner similar to the
* shared work scheduler, except that it takes a template parameter determining
* which pool to draw fibers from. In this fashion, one group of threads can share
* a pool of fibers among themselves while another group of threads can work with
* a completely separate pool
* @tparam PoolNumber The index of the pool number for this thread
*/
template <int PoolNumber>
class SharedWorkPool : public boost::fibers::algo::algorithm
{
typedef std::deque<boost::fibers::context * > ReadyQueueType;
typedef boost::fibers::scheduler::ready_queue_type LocalQueueType;
typedef std::unique_lock<std::mutex> LockType;
public:
SharedWorkPool() = default;
~SharedWorkPool() override {}
SharedWorkPool( bool suspend) : suspendable{suspend}{}
SharedWorkPool( SharedWorkPool const&) = delete;
SharedWorkPool( SharedWorkPool &&) = delete;
SharedWorkPool& operator=(const SharedWorkPool&) = delete;
SharedWorkPool& operator=(SharedWorkPool&&) = delete;
void awakened(boost::fibers::context* ctx) noexcept override;
boost::fibers::context* pick_next() noexcept override;
bool has_ready_fibers() const noexcept override
{
LockType lock{readyQueueMutex};
return ((!readyQueue.empty()) || (!localQueue.empty()));
}
void suspend_until(const std::chrono::steady_clock::time_point& timePoint) noexcept override;
void notify() noexcept override;
private:
static ReadyQueueType readyQueue;
static std::mutex readyQueueMutex;
LocalQueueType localQueue{};
std::mutex instanceMutex{};
std::condition_variable suspendCondition{};
bool waitNotifyFlag{false};
bool suspendable{false};
};
template <int PoolNumber>
void SharedWorkPool<PoolNumber>::awakened(boost::fibers::context* ctx) noexcept
{
if(ctx->is_context(boost::fibers::type::pinned_context))
{ // we have been passed the thread's main fiber, never put those in the shared queue
localQueue.push_back(*ctx);
}
else
{//worker fiber, enqueue on shared queue
ctx->detach();
LockType lock{readyQueueMutex};
readyQueue.push_back(ctx);
}
}
template <int PoolNumber>
boost::fibers::context* SharedWorkPool<PoolNumber>::pick_next() noexcept
{
boost::fibers::context * ctx = nullptr;
LockType lock{readyQueueMutex};
if(!readyQueue.empty())
{ //pop an item from the ready queue
ctx = readyQueue.front();
readyQueue.pop_front();
lock.unlock();
BOOST_ASSERT( ctx != nullptr);
boost::fibers::context::active()->attach( ctx); //attach context to current scheduler via the active fiber of this thread
}
else
{
lock.unlock();
if(!localQueue.empty())
{ //nothing in the ready queue, return main or dispatcher fiber
ctx = & localQueue.front();
localQueue.pop_front();
}
}
return ctx;
}
template <int PoolNumber>
void SharedWorkPool<PoolNumber>::suspend_until(const std::chrono::steady_clock::time_point& timePoint) noexcept
{
if(suspendable)
{
if (std::chrono::steady_clock::time_point::max() == timePoint)
{
LockType lock{instanceMutex};
suspendCondition.wait(lock, [this](){return waitNotifyFlag;});
waitNotifyFlag = false;
}
else
{
LockType lock{instanceMutex};
suspendCondition.wait_until(lock, timePoint, [this](){return waitNotifyFlag;});
waitNotifyFlag = false;
}
}
}
template <int PoolNumber>
void SharedWorkPool<PoolNumber>::notify() noexcept
{
if(suspendable)
{
LockType lock{instanceMutex};
waitNotifyFlag = true;
lock.unlock();
suspendCondition.notify_all();
}
}
template <int PoolNumber>
std::deque<boost::fibers::context*> SharedWorkPool<PoolNumber>::readyQueue{};
template <int PoolNumber>
std::mutex SharedWorkPool<PoolNumber>::readyQueueMutex{};
注意，如果您尝试使用不同编译单元中声明中的相同池号，我不确定是否会发生。但是，在正常情况下，即您只为每个boost::fibers::use_scheduling_algorithm< Threads::Fibers::SharedWorkPool<WorkPoolNumber> >();在单个位置写了WorkPoolNumber，效果很好。分配给一组给定线程的光纤始终在同一组线程内运行，而不会由另一组线程运行。