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在Java中将工作负载动态分配到多个线程(Dynamically distributing workload to multiple threads in Java)

 假设我有5个线程，必须为并行蒙特卡罗方法程序总共进行1,000,000函数调用。 我为5个线程中的每个线程分配了1,000,000 / 5函数调用。 然而，经过多次测试（一些测试范围高达1万亿次迭代），我意识到有些线程的完成速度比其他线程快得多。 因此，我想动态地为每个线程分配工作负载。 我的第一种方法涉及一个AtomicLong变量，它被设置为初始值，比方说，10亿。 在每个函数调用之后，我会将AtomicLong递减1.在每个函数调用之前，程序会检查AtomicLong是否大于0 ，如下所示：  
AtomicLong remainingIterations = new AtomicLong(1000000000);
ExecutorService threadPool = Executors.newFixedThreadPool(5);

for (int i = 0; i < 5; i++) {//create 5 threads
   threadPool.submit(new Runnable() {
       public void run() {
          while (remainingIterations.get() > 0) {//do a function call if necessary 
             remainingIterations.decrementAndGet();//decrement # of remaining calls needed
             doOneFunctionCall();//perform a function call
          }
       }
   });
}//more unrelated code is not show (thread shutdown, etc.)
 
 这种方法似乎非常慢，我正确使用AtomicLong吗？ 有更好的方法吗？ 

Let's say I have 5 threads that must make a combined total of 1,000,000 function calls for a parallel Monte Carlo Method program. I assigned 1,000,000 / 5 function calls for each of the 5 threads. However, after many tests (some tests ranging up to 1 trillion iterations) I realized that some threads were finishing much faster than others. So instead I would like to dynamically assign workload to each of these threads. My first approach involved a AtomicLong variable that was set to an initial value of, let's say, 1 billion. After each function call, I would decrement the AtomicLong by 1. Before every function call the program would check to see if the AtomicLong was greater than 0, like this: 
AtomicLong remainingIterations = new AtomicLong(1000000000);
ExecutorService threadPool = Executors.newFixedThreadPool(5);

for (int i = 0; i < 5; i++) {//create 5 threads
   threadPool.submit(new Runnable() {
       public void run() {
          while (remainingIterations.get() > 0) {//do a function call if necessary 
             remainingIterations.decrementAndGet();//decrement # of remaining calls needed
             doOneFunctionCall();//perform a function call
          }
       }
   });
}//more unrelated code is not show (thread shutdown, etc.)
 
This approach seemed to be extremely slow, am I using AtomicLong correctly? Is there a better approach?

原文：https://stackoverflow.com/questions/39734670

更新时间：2022-11-27 08:11

最满意答案

 对于新窗口，可能类似于SW_SHOWNA / SWP_NOACTIVATE？ 

int HandledWidget::showPopup()
{
    int nRet(-1);

    show(SW_SHOWNOACTIVATE);

    BOOL bMenuDestroyed(FALSE);
    BOOL bMsgQuit(FALSE);
    HWND m_hWndOwner = GetWindow(m_hWnd, GW_OWNER);
    assert(GetForegroundWindow() == m_hWndOwner);

    while(TRUE)
    {
        if(GetProp(m_hWnd, MENU_EXIT_NOTIFY) != 0)
        {
            nRet = (int)GetProp(m_hWnd, MENU_EXIT_COMMAND_ID);
            break;
        }

        if(GetActiveWindow() != m_hWndOwner)
        {
            break;
        }

        m_bIsPopingUp = true;

        MSG msg = {0};
        if(PeekMessage(&msg, NULL, 0, 0, PM_REMOVE))
        {
            if(msg.message == WM_KEYDOWN
                || msg.message == WM_SYSKEYDOWN
                || msg.message == WM_KEYUP
                || msg.message == WM_SYSKEYUP
                || msg.message == WM_CHAR
                || msg.message == WM_IME_CHAR
                || msg.message == WM_MOUSEWHEEL
                )
            {
                //transfer the message to menu window
                msg.hwnd = m_hWnd;
            }
            else if(msg.message == WM_LBUTTONDOWN
                || msg.message == WM_RBUTTONDOWN
                || msg.message == WM_NCLBUTTONDOWN
                || msg.message == WM_NCRBUTTONDOWN)
            {
                //click on other window
                if(msg.hwnd != m_hWnd)
                {
                    m_bIsPopingUp = false;
                    DestroyWindow(m_hWnd);
                    bMenuDestroyed = TRUE;
                }
            }
            else if(msg.message == WM_QUIT)
            {
                bMsgQuit = TRUE;
            }

            TranslateMessage (&msg);
            DispatchMessageW (&msg);
        }
        else
        {
            MsgWaitForMultipleObjects (0, 0, 0, 10, QS_ALLINPUT);
        }

        if(bMenuDestroyed) break;

        if(bMsgQuit)
        {
            PostQuitMessage(msg.wParam);
            break;
        }
    }

    m_bIsPopingUp = false;

    if(!bMenuDestroyed) DestroyWindow(m_hWnd);

    return nRet;
}

bool HandledWidget::exitPopup(int nCommandId)
{
    BOOL bRet = SetProp(m_hWnd, MENU_EXIT_NOTIFY, (HANDLE)1);
    SetProp(m_hWnd, MENU_EXIT_COMMAND_ID, (HANDLE)nCommandId);
    return bRet;
}
 
and handle wm_mouseactivate: 
LRESULT ComboxList::onMouseActivate( WPARAM wParam, LPARAM lParam, bool &bHandled )
{
    bHandled = true;
    return MA_NOACTIVATE;
}
 
remember do not activate the new window using SetFocus/SetWindowPos(SW_SHOWWINDOW)/ShowWindow(SW_SHOW)/SetActivate/SetForegroundWindow etc. 
Then you get a non-activate window just like the system menu. 
reference:http://www.cppblog.com/weiym/archive/2013/04/07/199189.html

在Java中将工作负载动态分配到多个线程(Dynamically distributing workload to multiple threads in Java)

最满意答案

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