4

在询问是否有比 boost::object_pool 更快的堆分配/释放机制可用？我得到反馈说这个对象池不是线程安全的。

所以我写了一个 ObjectFactory 包装 boost::object_pool 并添加互斥锁：

#include <memory>
using std::shared_ptr;

#include <boost/pool/object_pool.hpp>
#include <boost/thread/mutex.hpp>

template <typename T>
class ObjectFactory 
{
private:
    struct SharedDeleter 
    {
        ObjectFactory<T>* m_pFact;

        SharedDeleter(ObjectFactory<T>* fact) : m_pFact(fact) {}

        inline void operator()(T* p) const 
        {      
          m_pFact->destroy(p);
        }
    };


    boost::object_pool<T>   m_Pool;
    boost::mutex            m_PoolMutex;

    SharedDeleter           m_Deleter;


public:
    ObjectFactory() : m_Deleter(this)
    {
    }

    template<typename TType = T, typename... TArgs> 
    inline TType* create(TArgs&&... mArgs)
    {
        boost::unique_lock<boost::mutex> scoped_lock(m_PoolMutex);
        return m_Pool.construct(mArgs...);
    }

    inline void destroy(T* mObj) 
    { 
        boost::unique_lock<boost::mutex> scoped_lock(m_PoolMutex);
        m_Pool.destroy(mObj); 
    }


    template<typename TType = T, typename... TArgs> 
    inline std::shared_ptr<TType> make_shared(TArgs&&... mArgs)
    {
        return std::shared_ptr<TType>(this->create(mArgs...), m_Deleter);
    }

};

没有互斥锁的计时结果：

 With WithObjectFactory!: 
Start time: 1381682855810868000 nanoseconds since Jan 1, 1970
End time: 1381682863375427000 nanoseconds since Jan 1, 1970
Duration: 7.56456 seconds

 With WithObjectFactory and std::shared_ptr!: 
Start time: 1381682863375476000 nanoseconds since Jan 1, 1970
End time: 1381682879114065000 nanoseconds since Jan 1, 1970
Duration: 15.7386 seconds

使用互斥锁的计时结果：

 With WithObjectFactory!: 
Start time: 1381683562246086000 nanoseconds since Jan 1, 1970
End time: 1381683574399319000 nanoseconds since Jan 1, 1970
Duration: 12.1532 seconds

 With WithObjectFactory and std::shared_ptr!: 
Start time: 1381683574399378000 nanoseconds since Jan 1, 1970
End time: 1381683595103438000 nanoseconds since Jan 1, 1970
Duration: 20.7041 seconds

您看到的是，互斥锁占用了 20% 以上的时间，恕我直言，boost::object_pool 仅可用于单线程应用程序。

我的问题：我是否使用了正确的锁定机制？销毁是否也需要互斥锁？我在上面的代码中没有看到任何错误吗？

谢谢

编辑：用 std::map 测试但速度很慢。找到 boost::thread_specific_ptr ，它似乎工作：

#include <memory>
using std::shared_ptr;

#include <boost/pool/object_pool.hpp>
#include <boost/thread.hpp>

template <typename T>
class ObjectFactory 
{
private:
    struct SharedDeleter 
    {
        ObjectFactory<T>* m_pFact;

        SharedDeleter(ObjectFactory<T>* fact) : m_pFact(fact) {}

        inline void operator()(T* p) const 
        {      
          m_pFact->destroy(p);
        }
    };

    boost::thread_specific_ptr<boost::object_pool<T>>   m_tpPool;   
    SharedDeleter           m_Deleter;

public:
    ObjectFactory() : m_Deleter(this)
    {
        if ( !m_tpPool.get() )
            m_tpPool.reset(new boost::object_pool<T>());
    }

    template<typename TType = T, typename... TArgs> 
    inline TType* create(TArgs&&... mArgs)
    {
        return m_tpPool->construct(mArgs...);
    }

    inline void destroy(T* mObj) 
    { 
        m_tpPool->destroy(mObj);
    }

    template<typename TType = T, typename... TArgs> 
    inline std::shared_ptr<TType> make_shared(TArgs&&... mArgs)
    {
        return std::shared_ptr<TType>(this->create(mArgs...), m_Deleter);
    }
};

上面代码的结果：

 With WithObjectFactory!: 
Start time: 1381714923605177000 nanoseconds since Jan 1, 1970
End time: 1381714934202228000 nanoseconds since Jan 1, 1970
Duration: 10.5971 seconds

 With WithObjectFactory and std::shared_ptr!: 
Start time: 1381714934202285000 nanoseconds since Jan 1, 1970
End time: 1381714950900537000 nanoseconds since Jan 1, 1970
Duration: 16.6983 seconds
4

2 回答 2

1
  • 使用 std::mutex 和 boost:thread_specific_ptr 两者都会减慢
  • std::atomic_load(std::shared_ptr<...>*) 似乎不适用于 GCC 4.6
  • 使用此解决方案回退到良好的旧 pthread 调用

结果：在带有 GCC 4.6 的 Ubuntu LTS 12.04 上

 With OUT smartptrs (new and delete): 
Start time: 1381746876399819258 nanoseconds since Jan 1, 1970
End time: 1381746881851990579 nanoseconds since Jan 1, 1970
Duration: 5.45217 seconds

 With smartptrs (boost::shared_ptr withOUT make_shared): 
Start time: 1381746881852079492 nanoseconds since Jan 1, 1970
End time: 1381746889453586405 nanoseconds since Jan 1, 1970
Duration: 7.60151 seconds

 With smartptrs (boost::shared_ptr with make_shared): 
Start time: 1381746889453642790 nanoseconds since Jan 1, 1970
End time: 1381746896396534068 nanoseconds since Jan 1, 1970
Duration: 6.94289 seconds

 With STD smart_ptr (std::shared_ptr with make_shared): 
Start time: 1381746896396596314 nanoseconds since Jan 1, 1970
End time: 1381746902544346880 nanoseconds since Jan 1, 1970
Duration: 6.14775 seconds

 With UniquePtr (boost::unique_ptr): 
Start time: 1381746902544386766 nanoseconds since Jan 1, 1970
End time: 1381746907842640751 nanoseconds since Jan 1, 1970
Duration: 5.29825 seconds

 With STD UniquePtr (std::unique_ptr): 
Start time: 1381746907842679994 nanoseconds since Jan 1, 1970
End time: 1381746913141429138 nanoseconds since Jan 1, 1970
Duration: 5.29875 seconds

 With Object Pool (boost::object_pool<>): 
Start time: 1381746913141469017 nanoseconds since Jan 1, 1970
End time: 1381746917062689541 nanoseconds since Jan 1, 1970
Duration: 3.92122 seconds


 With Thread Safe ObjectFactory<TestClass>...
Start time: 1381746917062729671 nanoseconds since Jan 1, 1970
End time: 1381746921388452186 nanoseconds since Jan 1, 1970
Duration: 4.32572 seconds

 With Thread Safe ObjectFactory<TestClass> and std::shared_ptr...
Start time: 1381746921388491395 nanoseconds since Jan 1, 1970
End time: 1381746928808481617 nanoseconds since Jan 1, 1970
Duration: 7.41999 seconds

所以 Thread Safe ObjectFactory 仍然比使用普通的 new & delete 快 1 秒以上。

谁有更好的建议欢迎补充！

感谢所有有用的反馈！

编辑：使用 __thread gnu 选项也可以快速工作：

#include <memory>
#include <boost/pool/object_pool.hpp>

template <typename T>
class ObjectFactory 
{
private:
    struct SharedDeleter 
    {
        ObjectFactory<T>* m_pFact;

        SharedDeleter(ObjectFactory<T>* fact) : m_pFact(fact) {}

        inline void operator()(T* p) const 
        {      
          m_pFact->destroy(p);
        }
    };

    static __thread boost::object_pool<T>* m_tlsPool;
    SharedDeleter           m_Deleter;

public:
    ObjectFactory() :  m_Deleter(this)
    {
        m_tlsPool = new boost::object_pool<T>();
    }

    virtual ~ObjectFactory() 
    {
        delete m_tlsPool;
    }

    template<typename TType = T, typename... TArgs> 
    inline TType* create(TArgs&&... mArgs)
    {
        return m_tlsPool->construct(mArgs...);       
    }

    inline void destroy(T* mObj) 
    { 
        m_tlsPool->destroy(mObj);
    }

    template<typename TType = T, typename... TArgs> 
    inline std::shared_ptr<TType> make_shared(TArgs&&... mArgs)
    {
        return std::shared_ptr<TType>(this->create(mArgs...), m_Deleter);
    }
};

template<typename T>
/*static*/__thread boost::object_pool<T>* ObjectFactory<T>::m_tlsPool(NULL);

但是 m_tlsPool 不需要是静态的吗？

于 2013-10-14T10:44:20.117 回答
0

我认为您仍然需要对 m_Deleter 进行同步，因为 shared_ptr 可以从另一个线程中释放。

于 2014-01-09T18:06:07.733 回答