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Keep .NET console application alive until the termination sequence finishes

I am working on a data acquisition application and I want to ensure that it exits gracefully. That is, it processes all the already collected data, flushes all the (file) buffers to "disk" (persistent memory) and might even uploads the data to the cloud.
So, I wrote (based on this answer) the code below to catch every close event. (It is just a test code.)
Problem: If I use the X in the top-right corner of the console, the program gets terminated after a short delay, even though the termination sequence is still running. (The handler does get called, and it does start to wait for the threads to join but then it gets killed after a while.) If I terminate with Crt+C or Ctr+Break it works as intended; The termination sequence finishes and exits the process.
Question: How can I make the OS wait for my application to terminate instead of killing it off after a short grace period?
#region Trap application termination
[DllImport("Kernel32")]
private static extern bool SetConsoleCtrlHandler(EventHandler handler, bool add);
private delegate bool EventHandler(CtrlType sig);
static EventHandler _handler;
enum CtrlType
{
CTRL_C_EVENT = 0,
CTRL_BREAK_EVENT = 1,
CTRL_CLOSE_EVENT = 2,
CTRL_LOGOFF_EVENT = 5,
CTRL_SHUTDOWN_EVENT = 6
}
private static bool Handler(CtrlType sig, List<Thread> threads, List<Task> tasks, CancellationTokenSource cancellationRequest)
{
//starts new foregeound thread, so the process doesn't terminate when all the cancelled threads end
Thread closer = new Thread(() => terminationSequence(threads, tasks, cancellationRequest));
closer.IsBackground = false;
closer.Start();
closer.Join(); //wait for the termination sequence to finish
return true; //just to be pretty; this never runs (obviously)
}
private static void terminationSequence(List<Thread> threads, List<Task> tasks, CancellationTokenSource cancellationRequest)
{
cancellationRequest.Cancel(); //sends cancellation requests to all threads and tasks
//wait for all the tasks to meet the cancellation request
foreach (Task task in tasks)
{
task.Wait();
}
//wait for all the treads to meet the cancellation request
foreach (Thread thread in threads)
{
thread.Join();
}
/*maybe do some additional work*/
//simulate work being done
Stopwatch stopwatch = new Stopwatch();
stopwatch.Start();
Console.WriteLine("Spinning");
while (stopwatch.Elapsed.Seconds < 30)
{
if (stopwatch.Elapsed.Seconds % 2 == 0)
{
Console.Clear();
Console.WriteLine("Elapsed Time: {0}m {1}s", stopwatch.Elapsed.Minutes, stopwatch.Elapsed.Seconds);
}
Thread.SpinWait(10000);
}
Environment.Exit(0); //exit the process
}
#endregion
static void Main(string[] args)
{
CancellationTokenSource cancellationRequest = new CancellationTokenSource(); //cancellation signal to all threads and tasks
List<Thread> threads = new List<Thread>(); //list of threads
//specifys termination handler
_handler += new EventHandler((type) => Handler(type, threads, new List<Task>(), cancellationRequest));
SetConsoleCtrlHandler(_handler, true);
//creating a new thread
Thread t = new Thread(() => logic(cancellationRequest.Token));
threads.Add(t);
t.Start();
}

Since C# 7.1 you can have an async Task Main() method. Using this, you can modify your handler to create a method, and wait on it in the Main method.
Sidenote: you should use tasks instead of threads wherever you can. Tasks manage your thread better, and they run of the ThreadPool. When you create a new Thread instance, it's assuming it'll be a long running task, and the windows will treat it differently.
So with that in mind, consider wrapping the TerminateSequence method in a task, instead of a thread, and make that task a member of your class. Now you won't have to wait for it in the context of the handler, you could instead wait for it in the Main method.
With the rest of your code remaining the same, you could do the following:
private Task _finalTask;
private static bool Handler(CtrlType sig, List<Thread> threads, List<Task> tasks, CancellationTokenSource cancellationRequest)
{
//starts new foregeound thread, so the process doesn't terminate when all the cancelled threads end
_finalTask = Task.Run(() => terminationSequence(threads, tasks, cancellationRequest));
}
// ...
static async Task Main(string[] args)
{
// ...
// Wait for the termination process
if(_finalProcess != null)
await _finalTask
}
If you're not working with C# 7.1 you can still do this, it'll just be a little less elegant. All you need to do is wait for it:
_finalTask?.Wait();
And that should do it.

How to stop a thread if thread takes too long

I have a situation that i export data to a file and what i have been asked to do is to provide a cancel button which on click will stop the export if it takes too much time to export.
I started exporting to the file in a thread. And i try to abort the thread on the button click. But it do not work.
I searched on Google and i found that abort() is not recommended. But what else should I choose to achieve it?
My current code is:
private void ExportButtonClick(object param)
{
IList<Ur1R2_Time_Points> data = ct.T_UR.ToList();
DataTable dtData = ExportHelper.ToDataTable(data);
thread = new Thread(new ThreadStart(()=>ExportHelper.DataTableToCsv(dtData, "ExportFile.csv")));
thread.SetApartmentState(ApartmentState.STA);
thread.IsBackground = true;
thread.Name = "PDF";
thread.Start();
}
private void StopButtonClick(object param)
{
if (thread.Name == "PDF")
{
thread.Interrupt();
thread.Abort();
}
}

Aborting a thread is a bad idea, especially when dealing with files. You won't have a chance to clean up half-written files or clean-up inconsistent state.
It won't harm the .NET Runtime bat it can hurt your own application eg if the worker method leaves global state, files or database records in an inconsistent state.
It's always preferable to use cooperative cancellation - the thread periodically checks a coordination construct like a ManualResetEvent or CancellationToken. You can't use a simple variable like a Boolean flag, as this can lead to race conditions, eg if two or more threads try to set it at the same time.
You can read about cancellation in .NET in the Cancellation in Managed Threads section of MSDN.
The CancellationToken/CancellationTokenSource classes were added in .NET 4 to make cancellation easier that passing around events.
In your case, you should modify your DataTableToCsv to accept a CancellationToken. That token is generated by a CancellationTokenSource class.
When you call CancellationTokenSource.Cancel the token's IsCancellationRequested property becomes true. Your DataTableToCsv method should check this flag periodically. If it's set, it should exit any loops, delete any inconsistent files etc.
Timeouts are directly supported with CancelAfter. Essentially, CancelAfter starts a timer that will fire Cancel when it expires.
Your code could look like this:
CancellationTokenSource _exportCts = null;
private void ExportButtonClick(object param)
{
IList<Ur1R2_Time_Points> data = ct.T_UR.ToList();
DataTable dtData = ExportHelper.ToDataTable(data);
_exportCts=new CancellationTokenSource();
var token=_exportCts.Token;
thread = new Thread(new ThreadStart(()=>
ExportHelper.DataTableToCsv(dtData, "ExportFile.csv",token)));
thread.SetApartmentState(ApartmentState.STA);
thread.IsBackground = true;
thread.Name = "PDF";
_exportCts.CancelAfter(10000);
thread.Start();
}
private void StopButtonClick(object param)
{
if (_exportCts!=null)
{
_exportCts.Cancel();
}
}
DataTableToCsv should contain code similar to this:
foreach(var row in myTable)
{
if (token.IsCancellationRequested)
{
break;
}
//else continue with processing
var line=String.Join(",", row.ItemArray);
writer.WriteLine(line);
}
You can clean up your code quite a bit by using tasks instead of raw threads:
private async void ExportButtonClick(object param)
{
IList<Ur1R2_Time_Points> data = ct.T_UR.ToList();
DataTable dtData = ExportHelper.ToDataTable(data);
_exportCts=new CancellationTokenSource();
var token=_exportCts.Token;
_exportCts.CancelAfter(10000);
await Task.Run(()=> ExportHelper.DataTableToCsv(dtData, "ExportFile.csv",token)));
MessageBox.Show("Finished");
}
You could also speed it up by using asynchronous operations, eg to read data from the database or write to text files without blocking or using threads. Windows IO (both file and network) is asynchronous at the driver level. Methods like File.WriteLineAsync don't use threads to write to a file.
Your Export button handler could become :
private void ExportButtonClick(object param)
{
IList<Ur1R2_Time_Points> data = ct.T_UR.ToList();
DataTable dtData = ExportHelper.ToDataTable(data);
_exportCts=new CancellationTokenSource();
var token=_exportCts.Token;
_exportCts.CancelAfter(10000);
await Task.Run(async ()=> ExportHelper.DataTableToCsv(dtData, "ExportFile.csv",token)));
MessageBox.Show("Finished");
}
and DataTableToCsv :
public async Task DataTableToCsv(DataTable table, string file,CancellationToken token)
{
...
foreach(var row in myTable)
{
if (token.IsCancellationRequested)
{
break;
}
//else continue with processing
var line=String.Join(",", row.ItemArray);
await writer.WriteLineAsync(line);
}

You can use a boolean flag. Use a volatile boolean for that.
In the helper do something like:
this.aborted = false;
while(!finished && !aborted) {
//process one row
}
Whenever you want to cancel the operation, you call a method to set aborted to true:
public void Abort() {
this.aborted = true;
}

Have a read here: https://msdn.microsoft.com/en-us/library/system.threading.threadabortexception(v=vs.110).aspx
When a call is made to the Abort method to destroy a thread, the common language runtime throws a ThreadAbortException. ThreadAbortException is a special exception that can be caught, but it will automatically be raised again at the end of the catch block. When this exception is raised, the runtime executes all the finally blocks before ending the thread. Because the thread can do an unbounded computation in the finally blocks or call Thread.ResetAbort to cancel the abort, there is no guarantee that the thread will ever end. If you want to wait until the aborted thread has ended, you can call the Thread.Join method. Join is a blocking call that does not return until the thread actually stops executing.
Since Thread.Abort() is executed by another thread, it can happen anytime and when it happens ThreadAbortException is thrown on target thread.
Inside ExportHelper.DataTableToCsv:
catch(ThreadAbortException e) {
Thread.ResetAbort();
}
On StopButtonClick
if (thread.Name == "PDF")
{
thread.Interrupt();
thread.Join();
}

To Stop a thread you have one option of Thread.Abort.However because this method thrown ThreadAbortException on the target thread when it executed by another thead.
Which is not recommended.
The second option to stop a thread is by using shared variable that both your target and your calling thread can access.
See the Example ::
public static class Program
{
public static void ThreadMethod(object o)
{
for (int i = 0; i < (int)o; i++)
{
Console.WriteLine("ThreadProc: { 0}", i);
Thread.Sleep(0);
}
}
public static void Main()
{
bool stopped = false;
Thread t = new Thread(new ThreadStart(() =>
{
while (!stopped)
{
Console.WriteLine("Running...");
Thread.Sleep(1000);
}
}));
t.Start();
Console.WriteLine("Press any key to exit");
Console.ReadKey();
stopped = true;
t.Join();
}
}
//Source :: Book --> Programming in c#

Catch exception in current thread when it's thrown in different thread

My situation is:
from main thread i start thread A.
In main thread there some while(true) which run a lot of time. Inside of while is time consumption operations:
static void Main(string[] args)
{
new Thread(Go).Start();
while (true)
{
Thread.Sleep(1000);
}
}
private static void Go()
{
}
I wish generate exception in main thread if something go wrong in thread A
I read some articles, for example this one: catch exception that is thrown in different thread
and the only answer is: using shared variable (one of answers)
So, solution:
static void Main(string[] args)
{
new Thread(Go).Start();
while (true)
{
Thread.Sleep(1000);
if (_bad)
{
throw new Exception();
}
}
}
private static void Go()
{
Thread.Sleep(4000);
_bad = true;
}
is unacceptable, because i wish get exception ASAP. Not wait for loop cycling. For example, if i do cook cookies in while loop, i do not want wait for next cycle when i heat out: when heater is broken i wish in same moment generate exception in main thread.
Now, i can not pass delegates to thread: if i call delegate from thread A, is can not cut while loop, because it other thread. Same thing about events.
How can i handle this problem?
Thanks

The best way to achieve this is using the Task Parallel Library. If you start your task with TaskCreationOptions.LongRunning, a new thread will be created for the execution of the body of the task. You can then either access Task<T>.Result or call Wait from the main thread, and the exception (if any) will be propagated back to the thread. Use a CancellationTokenSource to support cancellation of other operations that are executing concurrently with the Go operation.
In the following example, calls to Thread.Sleep are placeholders for application-specific time consuming operations.
private static CancellationTokenSource _cancellationTokenSource =
new CancellationTokenSource();
static void Main(string[] args)
{
Task longRunning = Task.Factory.StartNew(Go, TaskCreationOptions.LongRunning);
while (true)
{
// Pass _cancellationTokenSource.Token to worker items to support
// cancelling the operation(s) immediately if the long running
// operation throws an exception
Thread.Sleep(1000);
// this will throw an exception if the task faulted, or simply continue
// if the task is still running
longRunning.Wait(0);
}
}
private static void Go()
{
try
{
Thread.Sleep(4000);
throw new Exception("Oh noes!!");
}
catch
{
_cancellationTokenSource.Cancel();
throw;
}
}

As some of the related questions suggest, use a BackgroundWorker. If the worker thread raises an exception, it gets passed to the main thread via the RunWorkerCompleted event. See http://msdn.microsoft.com/en-us/library/system.componentmodel.backgroundworker.runworkercompleted(v=vs.110).aspx.

Set thread lifetime at startup

Is there a way to set a value for how long a thread should (maximally) be alive when you start the thread?
Said in another way, with "pseudocode", is there anything like this:
Thread t = new Thread();
t.start();
t.abort_after_x_seconds(30);
which would make the thread abort if it lived more than 30 seconds.
Edit: I still can't get it to work, what I originally had is:
while(true)
{
if(...)
{
Thread t = new Thread(new ThreadStart(startMethod));
t.start();
}
Thread.sleep(...);
}
the problem is that sometimes the threads will hang (I'm not implementing what the threads do so I don't know exactly why (it's a school project, we're noobs at organizing)), so I want to kill those threads. I tried using Tasks and CancellationTokens as in the examples below, but when the Task hangs
it can't check if a cancellation request has occured.

Most of the time, you shouldn't be using Threads, use Tasks instead. They are more convenient and more efficient.
Aborting something is not safe, you should use cooperative cancellation instead. If you're calling a method that supports cancellation, then just pass it a cancellation token that will be cancelled after 30 seconds.
So your code could look like this (using .Net 4.5):
var cts = new CancellationTokenSource(TimeSpan.FromSeconds(30)));
var task = Task.Run(() => YourMethod(cts.Token), cts.Token);

[EDIT: My response was far too slow. But I'll leave this here for the sample code.]
You should use co-operative cancellation for this purpose. The thread itself will need to detect when it should exit, and respond appropriately.
There's a thing called a CancellationToken produced from a CancellationTokenSource that you can use for this purpose.
There's even a CancellationTokenSource constructor which lets you set a timeout.
Here's some sample code to demonstrate its use:
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Threading;
using System.Threading.Tasks;
namespace Demo
{
class Program
{
private void run()
{
using (var tokenSource = new CancellationTokenSource(TimeSpan.FromSeconds(30)))
{
var task = Task.Run(() => exampleOne(tokenSource.Token));
task.Wait();
}
using (var tokenSource = new CancellationTokenSource(TimeSpan.FromSeconds(30)))
{
var task = Task.Run(() => exampleTwo(tokenSource.Token));
task.Wait();
}
Console.WriteLine("Done.");
}
static void exampleZero()
{
Console.WriteLine("Starting exampleZero()");
try
{
Thread.Sleep(10000); // Simulate work.
}
catch (OperationCanceledException)
{
Console.WriteLine("Operation cancelled.");
}
Console.WriteLine("Exiting exampleZero()");
}
static void exampleOne(CancellationToken cancellation)
{
Console.WriteLine("Starting exampleOne()");
// Busy loop processing.
while (!cancellation.IsCancellationRequested)
{
// Do some work.
}
Console.WriteLine("Exiting exampleOne()");
}
static void exampleTwo(CancellationToken cancellation)
{
Console.WriteLine("Starting exampleTwo()");
while (!cancellation.WaitHandle.WaitOne(100)) // Wait 100ms between work.
{
// Do some work.
}
Console.WriteLine("Exiting exampleTwo()");
}
static void Main()
{
new Program().run();
}
}
}

As commenters have said, using Abort is bad practice and not guaranteed to abort immediately.
Why would you want to keep the thread alive? The thread will be released back to the pool when the task assigned to it is completed. The next time the task is run on the thread will automatically be given from the pool of threads either by creating another new one or re-using one that is available in the threadpool.
Sounds like your logic/code is bad and needs to be fixed rather than waiting for something for x seconds then terminating it, which in itself will cause knock on problems.
Perhaps you need a timer instead which can tick after 30 seconds then you can disable the timer and kill the task at hand.

Stopping a Thread, ManualResetEvent, volatile boolean or cancellationToken

I have a Thread (STAThread) in a Windows Service, which performs a big amount of work. When the windows service is restarted I want to stop this thread gracefully.
I know of a couple of ways
A volatile boolean
ManualResetEvent
CancellationToken
As far as I have found out Thread.Abort is a no go...
What is the best practice ?
The work is perfomed in another class than the one where the thread is started, so it is necessary to either introduce a cancellationToken parameter in a constructor or for example have a volatile variable. But I just can't figure out what is smartest.
Update
Just to clarify a little I have wrapped up a very simple example of what I'm talking about. As said earlier, this is being done in a windows service. Right now I'm thinking a volatile boolean that is checked on in the loop or a cancellationToken....
I cannot wait for the loop to finish, as stated below it can take several minutes, making the system administrators of the server believe that something is wrong with the service when they need to restart it.... I can without problems just drop all the work within the loop without problems, however I cannot do this with a Thread.Abort it is "evil" and furthermore a COM interface is called, so a small clean up is needed.
Class Scheduler{
private Thread apartmentThread;
private Worker worker;
void Scheduling(){
worker = new Worker();
apartmentThread = new Thread(Run);
apartmentThread.SetApartmentState(ApartmentState.STA);
apartmentThread.Start();
}
private void Run() {
while (!token.IsCancellationRequested) {
Thread.Sleep(pollInterval * MillisecondsToSeconds);
if (!token.IsCancellationRequested) {
worker.DoWork();
}
}
}
}
Class Worker{
//This will take several minutes....
public void DoWork(){
for(int i = 0; i < 50000; i++){
//Do some work including communication with a COM interface
//Communication with COM interface doesn't take long
}
}
}
UPDATE
Just examined performance, using a cancellationToken where the isCancelled state is "examined" in the code, is much faster than using a waitOne on a ManualResetEventSlim. Some quick figuers, an if on the cancellationToken iterating 100.000.000 times in a for loop costs me approx. 500 ms, where the WaitOne costs approx. 3 seconds. So performance in this scenario it is faster to use the cancellationToken.

You haven't posted enough of your implementation but I would highly recommend a CancellationToken if that is available to you. It's simple enough to use and understand from a maintainability standpoint. You can setup cooperative cancellation as well too if you decide to have more than one worker thread.
If you find yourself in a situation where this thread may block for long periods of time, it's best to setup your architecture so that this doesn't occur. You shouldn't be starting threads that won't play nice when you tell them to stop. If they don't stop when you ask them, the only real way is to tear down the process and let the OS kill them.
Eric Lippert posted a fantastic answer to a somewhat-related question here.

I tend to use a bool flag, a lock object and a Terminate() method, such as:
object locker = new object();
bool do_term = false;
Thread thread = new Thread(ThreadStart(ThreadProc));
thread.Start();
void ThreadProc()
{
while (true) {
lock (locker) {
if (do_term) break;
}
... do work...
}
}
void Terminate()
{
lock (locker) {
do_term = true;
}
}
Asides from Terminate() all the other fields and methods are private to the "worker" class.

Use a WaitHandle, most preferably a ManualResetEvent. Your best bet is to let whatever is in your loop finish. This is the safest way to accomplish your goal.
ManualResetEvent _stopSignal = new ManualResetEvent(false); // Your "stopper"
ManualResetEvent _exitedSignal = new ManualResetEvent(false);
void DoProcessing() {
try {
while (!_stopSignal.WaitOne(0)) {
DoSomething();
}
}
finally {
_exitedSignal.Set();
}
}
void DoSomething() {
//Some work goes here
}
public void Terminate() {
_stopSignal.Set();
_exitedSignal.WaitOne();
}
Then to use it:
Thread thread = new Thread(() => { thing.DoProcessing(); });
thread.Start();
//Some time later...
thing.Terminate();
If you have a particularly long-running process in your "DoSomething" implementation, you may want to call that asynchronously, and provide it with state information. That can get pretty complicated, though -- better to just wait until your process is finished, then exit, if you are able.

There are two situations in which you may find your thread:
Processing.
Blocking.
In the case where your thread is processing something, you must wait for your thread to finish processing in order for it to safely exit. If it's part of a work loop, then you can use a boolean flag to terminate the loop.
In the case where your thread is blocking, then you need to wake your thread and get it processing again. A thread may be blocking on a ManualResetEvent, a database call, a socket call or whatever else you could block on. In order to wake it up, you must call the Thread.Interrupt() method which will raise a ThreadInterruptedException.
It may look something like this:
private object sync = new object():
private bool running = false;
private void Run()
{
running = true;
while(true)
{
try
{
lock(sync)
{
if(!running)
{
break;
}
}
BlockingFunction();
}
catch(ThreadInterruptedException)
{
break;
}
}
}
public void Stop()
{
lock(sync)
{
running = false;
}
}
And here is how you can use it:
MyRunner r = new MyRunner();
Thread t = new Thread(()=>
{
r.Run();
});
t.IsBackground = true;
t.Start();
// To stop the thread
r.Stop();
// Interrupt the thread if it's in a blocking state
t.Interrupt();
// Wait for the thread to exit
t.Join();