c# – 关闭WinForm应用程序时的一次性对象生命周期

Foreground and Background Threads:

a background thread does not keep the managed execution environment running. Once all foreground threads have been stopped in a managed process (where the .exe file is a managed assembly),the system stops all background threads and shuts down.

这也适用于线程池中的线程,这些线程在启动新任务时默认使用,而不指定其他选项：

Task Schedulers

The default task scheduler is based on the .NET Framework 4 ThreadPool

Foreground and Background Threads:

Threads that belong to the managed thread pool (that is,threads whose IsThreadPoolThread property is true) are background threads.

关于申请终止的事实

在那之后,我还没有找到任何进一步的信息,在线程终止后发生了什么.我所做的,是简单的测试：

static void Main(string[] args)
{
    Task.Factory.StartNew(Method);
    Task.Delay(1000);
}

static void Method()
{
    try
    {
        while (true) { }
    }
    finally
    {
        File.WriteAllText(@"C:PolygonTest.txt","test");
    }
}

答案是,最终块没有被执行.

解决方案

ThreadAbortException – 不在这里

像ThreadAbortException这样的.NET中有一些功能称为线程终止的答案,但是：

When the common language runtime (CLR) stops background threads after all foreground threads in a managed executable have ended,it does not use Thread.Abort.

Process.Exited事件 – 不在这里

如果您运行其他进程,可以使用以下代码：

var myProcess = new Process();
myProcess.EnableRaisingEvents = true;
myProcess.Exited += new EventHandler(CleanUp);

但是,对于当前流程,这也不起作用.

AppDomain.CurrentDomain.ProcessExit – 有效

但是,Avneesh建议的解决方案适用于当前流程：

static void Main(string[] args)
{
    AppDomain.CurrentDomain.ProcessExit += CleanUp;

    Task.Factory.StartNew(Method);
    Task.Delay(1000);
}

static void Method()
{
    try
    {
        while (true) { }
    }
    finally
    {
        CleanUp(null,EventArgs.Empty);
    }
}

static void CleanUp(object sender,EventArgs args)
{
    File.WriteAllText(@"C:PolygonTest.txt","test");
}

流程终止

有关rosources的问题的答案可以在Terminating a Process文章中找到：

• Any remaining threads in the process are marked for termination.
• Any resources allocated by the process are freed.
• All kernel objects are closed.
• The process code is removed from memory.
• The process exit code is set.
• The process object is signaled.

以及如何终止进程：

• Any thread of the process calls the ExitProcess function. Note that some implementation of the C run-time library (CRT) call ExitProcess if the primary thread of the process returns.
• The last thread of the process terminates.
• Any thread calls the TerminateProcess function with a handle to the process.
• For console processes,the default console control handler calls ExitProcess when the console receives a CTRL+C or CTRL+BREAK signal.
• The user shuts down the system or logs off.

数据库连接

连接是一种资源,因此如果处理终止,则释放其所有资源.我检查了它在实践中的样子.

C#代码：

SqlConnection connection = new SqlConnection("Data Source=.;Initial Catalog=[database_name];Integrated Security=True");
connection.Open();
Debugger.Launch();
connection.Close();
connection.Dispose();

会话查找的T-SQL查询：

SELECT COUNT(*) FROM sys.dm_exec_sessions
WHERE nt_user_name = '[user_name]' AND program_name = '.Net SqlClient Data Provider'

我注意到,对于每个新连接,都创建了新会话.最有趣的是,在明确关闭或处理连接后,该会话未被释放.但是 – 目前我们感兴趣的领域 – 会话在申请流程终止时被释放.