Question

我正在运行简单的控制台迁移。我通过批量750件物品捆绑工作量，并通过以下方式将其发送到我的ThreadPool：

ThreadPool.QueueUserWorkItem(workerArray[i]._DoWork, i);

我在执行_DoWork方法时添加了一些日志，并输出：

Thread 1 started working...
Thread 2 started working...
Thread 1 is done working

超过400次

但是在每个开始和结束时，我还记录了通过输出运行的线程数（我在SO中找到的）：

((IEnumerable)System.Diagnostics.Process.GetCurrentProcess().Threads)
                .OfType<System.Diagnostics.ProcessThread>()
                .Where(t => t.ThreadState == System.Diagnostics.ThreadState.Running)
                .Count();

但是为什么当我有超过100个启动线程并且还没有完成时它只输出2到4个线程？

=============

更多代码

这是排队工作的原因：

for (var i = 0; i < taskCount; i++)
        {
            int itemCount = queueLength;

            if (i * queueLength + itemCount > journalIDs.Count)
                itemCount = (journalIDs.Count) - (i * queueLength);

            var queue = journalIDs.GetRange(i * queueLength, itemCount);

            doneEvents[i] = new ManualResetEvent(false);
            dbWorkers[i] = new DBWorker();

            var loadedQueue = db.GetJournalByIDs(queue);

            workerArray[i] = new JournalWorker(dbWorkers[i], loadedQueue, doneEvents[i]);

            ThreadPool.QueueUserWorkItem(workerArray[i]._DoWork, i);
        }

这是DoWork的作用：

public void _DoWork（Object pThreadContext）{

        int theThreadIndex = (int)pThreadContext;
        Console.WriteLine("Thread {0} started...", theThreadIndex);
        var threads = ((IEnumerable)System.Diagnostics.Process.GetCurrentProcess().Threads)
                .OfType<System.Diagnostics.ProcessThread>()
                .Where(t => t.ThreadState == System.Diagnostics.ThreadState.Running)
                .Count();

        Console.WriteLine("There's {0} thread(s) currently running", threads);

        foreach (var item in Queue)
        {

            var update = ShouldUpdate(item);

            if (update != null)
            {
                //Do some db operation
            }
            else
            {
                //Do some db operation
            }
        }

        Console.WriteLine("Thread {0} started saving...", theThreadIndex);
        Save(Store);

        Console.WriteLine("Thread {0} done working with " + Store.Count + " objects...", theThreadIndex);

        threads = ((IEnumerable)System.Diagnostics.Process.GetCurrentProcess().Threads)
                .OfType<System.Diagnostics.ProcessThread>()
                .Where(t => t.ThreadState == System.Diagnostics.ThreadState.Running)
                .Count();
        Console.WriteLine("There's {0} thread(s) currently running", threads);
        db.Clear();
        db = null;
        _doneEvent.Set();


    }

Answer 1

这里有几件事需要考虑

ThreadPool最大并发线程默认基于.NET 4.0中的几个不同因素。您可以通过调用GetMaxThreads
等待ManualResetEvent时，ThreadState将是WaitSleepJoin，而不是Running
控制台是线程安全的，但在多线程场景中使用时，不会为您提供可预测，准确定时，正确排序的输出

为什么运行线程的次数少于我发送给线程池的工作量

1 个答案: