---
lang: ja-jp
breaks: true
---
# C# シグナルを使って非同期処理を行う 2021-10-13

## CountdownEvent

軽量だとか。

> System.Threading.CountdownEvent
> https://qiita.com/rawr/items/6888778b53fc95c41f00#systemthreadingcountdownevent

> スレッドの相互作用、またはシグナリング
> https://docs.microsoft.com/ja-jp/dotnet/standard/threading/overview-of-synchronization-primitives#thread-interaction-or-signaling

> CountdownEvent
> https://docs.microsoft.com/ja-jp/dotnet/standard/threading/countdownevent

IEnumerable<Data> source = GetData();
using (CountdownEvent e = new CountdownEvent(1))
{
    // fork work:
    foreach (Data element in source)
    {
        // Dynamically increment signal count.
        e.AddCount();
        ThreadPool.QueueUserWorkItem(
            delegate(object state)
            {
                try
                {
                    ProcessData(state);
                }
                finally
                {
                    e.Signal();
                }
            },
            element
            );
    }
    e.Signal();

    // The first element could be run on this thread.

    // Join with work.
    e.Wait();
}
// .,.

## ManualResetEvent

###### tags: `C#` `シグナル` `非同期` `マルチスレッド` `CountdownEvent`