Question

我在我的大C ++应用程序中嵌入了Python3。 Python为自定义数据处理提供了用户脚本功能问题：我有许多与Python交互的线程，我真的不知道如何用GIL保护我的代码。到目前为止，我使代码工作的唯一方法是使用boost::mutex。

这是一个非常简单的例子，可以重现我的问题：

线程A首先调用Init()来初始化Python（静态函数）。
线程B调用Pythonize()在Python上做一些工作。线程B在第一次锁定GIL时被阻止。

代码：

#include <iostream>
#include <boost/thread.hpp>
#include <boost/bind.hpp>

#include "Python.h"

struct RTMaps_GILLock
{
    RTMaps_GILLock()
    {
        std::cout << "Locking..." << std::endl;
        m_state = PyGILState_Ensure();
    }

    ~RTMaps_GILLock()
    {
        std::cout << "Unlocking..." << std::endl;
        PyGILState_Release(m_state);
    }

private:
    PyGILState_STATE m_state;
};
#define GILLOCK RTMaps_GILLock lock;

class PythonEmbed
{
public:
    static void Init()
    {
        Py_Initialize();
        // EDIT : adding those two lines made my day :
        PyEval_InitThreads(); // This acquires GIL
        PyEval_SaveThread(); // Release the GIL
    }

    void Pythonize()
    {
        GILLOCK;
        // Never goes here :(
        std::cout << "OK" << std::endl;
    }
};

int main()
{
    PythonEmbed::Init();

    PythonEmbed pyt;
    boost::thread t(boost::bind(&PythonEmbed::Pythonize, pyt));

    t.join();
}

它在第一次锁定调用中死锁。控制台显示：锁定...

＆＃34; OK＆＃34;永远不会打印。我做错了什么？

编辑：更正了代码，现在它正在运行。我需要从主线程中释放GIL。

Answer 1

我有你的确切问题，请确保不要从主线程调用PyGILState_Ensure（），初始化Pythons，因为它需要一个完全不同的调用。我已经设置了一个线程映射器，每次调用我的acquirePython（）都会检查调用它的线程，如果它是主线程，它使用：

PyEval_SaveThread（）;

否则它存储GIL。这些是我班级的相关部分：

void MManager::acquirePython(void) {
    MThread thisThread = MFramework::MProcesses::GetCurrentThread();
    if (thisThread != mainThread) {
        Lock();
        std::map<MThread,void*>::iterator i = threadStates.find(thisThread);
        if (i == threadStates.end()) {
            Unlock();
            PyGILState_STATE gstate = PyGILState_Ensure();
            _PyGILState_STATE_* encState = new _PyGILState_STATE_;
            encState->state = gstate;
            encState->refCount = 1;
            Lock();
            threadStates[thisThread] = encState;
            Unlock();
        } else {
            _PyGILState_STATE_* encState = (_PyGILState_STATE_*)i->second;
            encState->refCount = encState->refCount + 1;
            Unlock();
        }

    } else {
        if (mainThreadState) PyEval_RestoreThread((PyThreadState*)mainThreadState);
    }

}

void MManager::releasePython(void) {
    MThread thisThread = MFramework::MProcesses::GetCurrentThread();
    if (thisThread != mainThread) {
        Lock();
        std::map<MThread,void*>::iterator i = threadStates.find(thisThread);
        if (i != threadStates.end()) {
            _PyGILState_STATE_* encState = (_PyGILState_STATE_*)i->second;
            if (encState->refCount <= 1) {
                threadStates.erase(i);
                Unlock();

                PyGILState_Release(encState->state);
                delete encState;
            } else {
                encState->refCount = encState->refCount - 1;
                Unlock();
            }
        } else {
            Unlock();
        }

    } else {
        mainThreadState = PyEval_SaveThread();
    }
}

Python GIL和线程

1 个答案: