Question

我使用了两个类：一个数据处理器，它将处理文件并计算每行中该字的实例总数。尝试使用多线程来执行此操作，其中将启动线程以在每一行中处理搜索。

存储向量中每一行的计数。

在没有多线程的情况下执行时，它可以正常运行。

    void DataProcessor::countInstance ()
    {
            int pos = -1, count = 0;
            string lineFromFile;
            cout << "In countInstance" <<endl;
            getline (m_file, lineFromFile);        <<<< Not getting line read from file
            while(true)
            {
                    pos = lineFromFile.find(mStr_word, ++pos);
                    if (pos != std::string::npos)
                            count++;
                    else
                            break;
            }
            mVec_countPerLine.push_back(count);
            cout <<mStr_word << "****" <<lineFromFile <<endl;
            cout << mVec_countPerLine[0]<<endl;
    }
    DataProcessor::~DataProcessor()
    {
            m_file.close();
    }

    ////////

    void *ThreadFunction (void *dp)
    {
            pthread_mutex_lock( &mutex1 );
            DataProcessor *dProcessor = static_cast<DataProcessor *> (dp); <<<just curious if casting is creating a problem

            cout << "IN ThreadFunction"<< endl;
            dProcessor->countInstance ();
            pthread_mutex_unlock( &mutex1 );
    }

    class MyThread
    {
    private:
            pthread_t threads[10];
    public:
            MyThread ();
            void createThread (DataProcessor *);
            ~MyThread ();
    };

这里我在循环中创建线程

    void MyThread::createThread (DataProcessor *dProcessor)
    {
            cout << "IN CREATE THREAD::";
            int numLinesInFile, rc;
            numLinesInFile = dProcessor->getNumLinesInFile();
            for ( int i =0; i < numLinesInFile; i++)
            {
                    rc = pthread_create(&threads[i], NULL,
                                            ThreadFunction, (void *)&dProcessor);
                    if (rc)
                    {
                            cout << "Error:unable to create thread," << rc << endl;
                            exit(-1);
                    }
            }
            for ( int i =0; i < numLinesInFile; i++)
                    pthread_join(threads[i], NULL);
            pthread_exit(NULL);
    }

    MyThread::~MyThread ()
    {
    }


    ########################################################
    Calling these two objects from:-

            dProcessor.openFile("example.txt");
            dProcessor.setWord(readData);
            MyThread thread;
            thread.createThread (&dProcessor);
            dProcessor.displayResult();

但是得到：

    IN CREATE THREAD::IN ThreadFunction
    In countInstance
    terminate called after throwing an instance of 'std::bad_cast'
      what():  std::bad_cast
    Aborted (core dumped)

任何人都可以帮我找出原因吗？

Answer 1

您的演员表示该参数是指向DataProcessor的指针：

 static_cast<DataProcessor *> (dp);

但是您将指针传递给指向DataProcessor的指针：

(void *)&dProcessor

失去演员阵容和＆符号：

rc = pthread_create(&threads[i], NULL, ThreadFunction, dProcessor);

顺便说一下：你永远不需要将指针投射到void*。

获取核心::程序随核心而中止

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