我不知道為什么我的 IOCP 的 numberOfConcurrentThreads 參數不起作用

Question

我已經閱讀了下面的材料並測試了一些代碼。 IOCP 是否創建自己的線程？

我的代碼如下：

#include <functional>
#include <stdio.h>
#include <iostream>
#include <crtdbg.h>
#include <conio.h>
#include <array>
#include <unordered_map>
using namespace std;

namespace IOCP_test {
    struct myOverlapped {
        OVERLAPPED overLapped;
        int number;
    };

    DWORD WINAPI myCallBack(LPVOID completionPort) {
        DWORD NumberOfByteTransfered = 0;
        VOID* CompletionKey = NULL;
        OVERLAPPED* overlappedPointer = NULL;


        while (true) {
            auto success = GetQueuedCompletionStatus(
                (HANDLE)completionPort,
                &NumberOfByteTransfered,
                (LPDWORD)&CompletionKey,
                &overlappedPointer,
                INFINITE);


            if (success) {
                myOverlapped* mO = (myOverlapped*)overlappedPointer;
                while (true) {
                    cout << mO->number << endl;
                }
                //Sleep(10);
                //PostQueuedCompletionStatus(completionPort, 0, 0, overlappedPointer);
            }
        }
    }


    void IOCP_test() { 
        // TODO: sleep을 안걸었는데.. 왜 5개 스레드가 모두 작동할까?
        int workerThreadCount = 5; 
        HANDLE hIOCP = CreateIoCompletionPort(INVALID_HANDLE_VALUE, NULL, 0, 1);
        vector<HANDLE> workerThreadVector;

        DWORD NumberOfByteTransfered = 0;
        VOID* CompletionKey = NULL;
        OVERLAPPED* overlappedPointer = NULL;

        for (DWORD i = 0; i < workerThreadCount; i++)
        {
            HANDLE WorkerThread = CreateThread(NULL, 0, myCallBack, hIOCP, 0, NULL);
            workerThreadVector.push_back(WorkerThread);
        }

        myOverlapped a1;
        a1.number = 1;

        myOverlapped a2;
        a2.number = 2;

        myOverlapped a3;
        a3.number = 3;

        myOverlapped a4;
        a4.number = 4;

        myOverlapped a5;
        a5.number = 5;

        if (hIOCP) {
            PostQueuedCompletionStatus(hIOCP, 0, 0, (LPOVERLAPPED)&a1);
            PostQueuedCompletionStatus(hIOCP, 0, 0, (LPOVERLAPPED)&a2);
            PostQueuedCompletionStatus(hIOCP, 0, 0, (LPOVERLAPPED)&a3);
            PostQueuedCompletionStatus(hIOCP, 0, 0, (LPOVERLAPPED)&a4);
            PostQueuedCompletionStatus(hIOCP, 0, 0, (LPOVERLAPPED)&a5);
        }

        char key;
        while (true) {
            key = _getch();

            if (key == 'e') {
                break;
            }

            if (key == 'n') {
                cout << endl;
            }
        }

        for (DWORD i = 0; i < workerThreadVector.size(); i++)
        {
            CloseHandle(workerThreadVector[i]);
        }

        if (hIOCP) {
            CloseHandle(hIOCP);
        }
    }
    //IOCP_test::IOCP_test();

}

int main()
{
    IOCP_test::IOCP_test();
    _CrtDumpMemoryLeaks();  
    return 0;
}

我想，如果 numberOfConcurrentThreads 有效，那么只有一個 cout '1' 應該運行的線程，而不是所有五個線程。

但是，結果如下。

所有重疊的工作都由工作線程處理..

為什么所有重疊的工作都由 5 個工作線程處理？ 我認為應該是 1 個工作線程，因為 numberOfConcurrentThreads 為 1。

我希望你的明智回答。 感謝您的閱讀。

Answer 1

我想到了。 這是因為我在工作線程的 function 中調用了“cout”。 我認為“cout”為我的工作線程調用 IO 中斷，它使 IOCP 向另一個工作線程發出信號。

我的測試代碼如下。 您可以運行此代碼，然后按除“e”以外的任何鍵。（“e”表示退出。）您可以看到哪個工作線程在 IOCP 中工作。

#include <functional>
#include <stdio.h>
#include <iostream>
#include <crtdbg.h>
#include <conio.h>
#include <array>
#include <unordered_map>

int iocp_test = -1;


namespace IOCP_test {
    struct myOverlapped {
        OVERLAPPED overLapped;
        int number;
    };

    DWORD WINAPI myCallBack(LPVOID completionPort) {
        DWORD NumberOfByteTransfered = 0;
        VOID* CompletionKey = NULL;
        OVERLAPPED* overlappedPointer = NULL;


        while (true) {
            auto success = GetQueuedCompletionStatus(
                (HANDLE)completionPort,
                &NumberOfByteTransfered,
                (LPDWORD)&CompletionKey,
                &overlappedPointer,
                INFINITE);


            if (success) {
                myOverlapped* mO = (myOverlapped*)overlappedPointer;
                while (true) {
                    iocp_test = mO->number;
                }
                //Sleep(10);
                //PostQueuedCompletionStatus(completionPort, 0, 0, overlappedPointer);
            }
        }
    }


    void IOCP_test() { 
        // sleep을 안걸었는데.. 왜 5개 스레드가 모두 작동할까? 
        // cout 같은 IO 인터럽트가 워커 스레드에서 호출되면 IOCP에서 그 스레드는 작업 중이 아닌 스레드로 판단하는 것 같다.
        int workerThreadCount = 5; 
        HANDLE hIOCP = CreateIoCompletionPort(INVALID_HANDLE_VALUE, NULL, 0, 2); 
        vector<HANDLE> workerThreadVector;

        DWORD NumberOfByteTransfered = 0;
        VOID* CompletionKey = NULL;
        OVERLAPPED* overlappedPointer = NULL;

        for (DWORD i = 0; i < workerThreadCount; i++)
        {
            HANDLE WorkerThread = CreateThread(NULL, 0, myCallBack, hIOCP, 0, NULL);
            workerThreadVector.push_back(WorkerThread);
        }

        myOverlapped a1;
        a1.number = 1;

        myOverlapped a2;
        a2.number = 2;

        myOverlapped a3;
        a3.number = 3;

        myOverlapped a4;
        a4.number = 4;

        myOverlapped a5;
        a5.number = 5;

        if (hIOCP) {
            PostQueuedCompletionStatus(hIOCP, 0, 0, (LPOVERLAPPED)&a1);
            PostQueuedCompletionStatus(hIOCP, 0, 0, (LPOVERLAPPED)&a2);
            PostQueuedCompletionStatus(hIOCP, 0, 0, (LPOVERLAPPED)&a3);
            PostQueuedCompletionStatus(hIOCP, 0, 0, (LPOVERLAPPED)&a4);
            PostQueuedCompletionStatus(hIOCP, 0, 0, (LPOVERLAPPED)&a5);
        }

        char key;
        while (true) {
            key = _getch();
            cout << iocp_test;
            if (key == 'e') {
                break;
            }

            if (key == 'n') {
                cout << endl;
            }

        }

        for (DWORD i = 0; i < workerThreadVector.size(); i++)
        {
            CloseHandle(workerThreadVector[i]);
        }

        if (hIOCP) {
            CloseHandle(hIOCP);
        }
    }
    //IOCP_test::IOCP_test();

}


int main()
{

    IOCP_test::IOCP_test();

    _CrtDumpMemoryLeaks();  
    return 0;
}