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How to interrupt a program by a key press

I want to interrupt my producer-consumer program by pressing the key T. I searched a lot of answers but i can't figure out why it is not working.
static void Main(string[] args)
{
Buffer buffer = new Buffer();
Produtor prod = new Produtor(buffer);
Thread threadProdutor = prod.CriarThreadProdutor();
Consumidor cons = new Consumidor(buffer, 100000);
Thread threadConsumidor = cons.CriarThreadConsumidor();
threadProdutor.Start();
threadConsumidor.Start();
threadProdutor.Join();
threadConsumidor.Join();
while (Console.KeyAvailable && Console.ReadKey(true).Key == ConsoleKey.T)
{
Environment.Exit(0);
}
}
I added a breakpoint in my while, but the program won't even get there.

By putting the loop after your Join() calls the threads will have already completed by the time you check the console for input, so you'll need to reverse the order.
Further, the while loop will only be entered and continue running if there is a key available and it is T. You want the opposite: loop until a key is available and it is T.
Finally, Console.ReadKey() blocks until a key is pressed, so you don't need to check Console.KeyAvailable, too, unless you want to do something else while you wait for T (such as display progress or check if the threads completed on their own).
while (Console.ReadKey(true).Key != ConsoleKey.T)
{
// Do nothing...
}
// T has been pressed
// Signal to the threads to stop
// Set a flag, Cancel() a CancellationTokenSource, etc.
// Wait for the threads to terminate
threadProdutor.Join();
threadConsumidor.Join();
// Exit the program
Environment.Exit(0);
To display progress while you wait for the interrupt key, you can rewrite the loop like this...
TimeSpan progressInterval = TimeSpan.FromSeconds(1);
// complete is a simple flag set by the consumer(s)
// Only call ReadKey() when KeyAvailable so it can't block longer than updateInterval
while (!complete && (!Console.KeyAvailable || Console.ReadKey(true).Key != ConsoleKey.T))
{
Console.WriteLine($"Current time is {DateTime.Now:HH:mm:ss.fff}");
Thread.Sleep(progressInterval);
}
Note that this has the downside of always sleeping for the entire progressInterval, even if the exit condition has been satisfied before then. A simple workaround would be to reduce the time between checks to 1 / n and then only display the progress after every nth check...
TimeSpan progressInterval = TimeSpan.FromSeconds(1);
const int ReadsPerProgressInterval = 10;
TimeSpan sleepTimeout = new TimeSpan(progressInterval.Ticks / ReadsPerProgressInterval);
int readCount = 0;
// complete is a simple flag set by the consumer(s)
// Only call ReadKey() when KeyAvailable so it can't block longer than updateInterval
while (!complete && (!Console.KeyAvailable || Console.ReadKey(true).Key != ConsoleKey.T))
{
// This won't display progress until after progressInterval has elapsed
// To display initial progress:
// A) change to == 1, or...
// B) duplicate progress display to before the loop as well
if (++readCount % ReadsPerProgressInterval == 0)
Console.WriteLine($"Current time is {DateTime.Now:HH:mm:ss.fff}");
Thread.Sleep(sleepTimeout);
}

Terminating a thread immediately and safely (C#)

I'm in the process of writing a simple "Score Attack" Poker game. A player assembles poker hands which are worth points as a timer ticks down. My problem is a game over scenario.
My game logic runs in a single thread since the game itself is so simple. I need to know how to terminate that thread as it is, with the player no longer able to make input. I've read on the MSDN that the safe way to do this is to use a loop to cause the thread's method to return and end the thread. The problem I run into is that my game requires user input, and the user input would cause the loop to not be checked at the moment the timer ticks to zero.
The code so far uses the Thread.Abort(), and it works, but from my searching on this site that is universally regarded as a bad idea. Is there any way I could set a condition that would terminate the thread safely regardless of methods within said thread needing input? (Console.ReadLine())
Code for the game loop and timer callback that aborts the thread:
private void GameLoop()
{
double stash = 0;
while (true)
{
player.SwapCards(gameDeck);
Table.WriteInfo("Stash This Hand? y/n");
if (Console.ReadLine().Equals("y"))
{
countdown += (int)ScoreHand(player.Hand);
stash += ScoreHand(player.Hand);
BankHand();
}
}
}
private void TimeDrop(object state)
{
countdown--;
Debug.WriteLine(countdown);
if (countdown == 0)
{
GameThread.Abort();
GameOverThread.Start();
Timer.Dispose();
}
}
As it sits the loop simply runs until the thread is aborted.
Edit:
Upon request, the code the starts the threads:
public Game()
{
gameDeck = new Deck();
InitPlayer();
DealHand();
countdown = 60;
GameThread = new Thread(GameLoop);
GameOverThread = new Thread(GameOver);
Timer = new Timer(new TimerCallback(TimeDrop), null, 0, 1000);
Timer.Change(0, 1000); //Ensures timer won't be garbage collected
GameThread.Start();
}

This sort of thing can be implemented easier and cleaner using async/await rather than threads.
First we need to wrap the blocking console input method with one that is cancellable (and async). The method polls the console using KeyAvailable and asynchronously delaying while checking the CancellationToken.
public static async Task<ConsoleKeyInfo> ReadKeyAsync(CancellationToken cancellationToken)
{
while (!Console.KeyAvailable)
{
await Task.Delay(100, cancellationToken);
}
return Console.ReadKey();
}
Now we can start this async method and pass a cancellation token from a CancellationTokenSource that will automatically cancel after a specific amount of time (10 seconds as an example).
public static async Task Main(string[] args)
{
Console.WriteLine("You have 10 seconds to press the Y key...");
var cts = new CancellationTokenSource(10_000);
try
{
while (true)
{
var key = await ReadKeyAsync(cts.Token);
if (key.Key == ConsoleKey.Y)
{
Console.WriteLine("Good job!");
break;
}
else
{
Console.WriteLine("Wrong Key");
}
}
}
catch (OperationCanceledException)
{
Console.Write("Time up!");
}
}

High CPU usage from while loop, checking for keypress event

I have a console application with two threads, one is doing repetitive time consuming work, the other is checking to see if the user has pressed the ESC key. If the ESC key was pressed, the time consuming work thread is paused, an "are you sure" message appears, and if yes is selected, the time consuming work thread finishes its current loop then exits.
The code I have to check for a key-press is using a lot of CPU resources due to the while (!breakCurrentOperation(work)) ; loop. How can I prevent this from happening?
Code:
public void runTimeConsumingWork()
{
HardWork work = new HardWork();
Thread workerThread = new Thread(() => work.StartWorking());
workerThread.Start(); // Start the hard work thread
while (!workerThread.IsAlive) ; // Hault untill Thread becomes Active
// Check if the user wants to stop the hard work
while (!breakCurrentOperation(work)) ;
// Cancle the hard work
work.Stop();
// Notify the User
UserInterfaceController.WriteToConsole("Operation Cancled...");
}
public static bool breakCurrentOperation(HardWork work)
{
if (Console.KeyAvailable)
{
var consoleKey = Console.ReadKey(true);
if (consoleKey.Key == ConsoleKey.Escape)
{
work.Pause(); // Pause
UserInterfaceController.WriteToConsole("Do you want to stop the current process? \nType s to stop or c to continue.");
string input = Console.ReadLine();
if (input == "c" || input == "C")
{
work.Pause(); // Unpause
return false; // Continue
}
else if (input == "s" || input == "S")
{
return true; // Break the loop
}
else
{
UserInterfaceController.WriteToConsole("Error: Input was not recognized, the current process will now continue. Press Esc to stop the operation.");
work.Pause(); // Unpause
}
}
}
return false;
}
If I place a Thread.Sleep(2000) in the main console UI thread, CPU usage goes way down, but the application becomes unresponsive with a 2 second delay.

Do you really have to constantly poll for input? If you are waiting for input in a separate thread, just use the Console.ReadKey. It will block the input thread, but your other thread will keep processing. You don't seem to be doing anything else on the input thread, so blocking shouldn't be an issue.

Look like your esc key press check logic running in end less loop due to while loop. Due to this the function keep utilizing the system resource.
To overcome this please use some delay in your loop using Thread.Sleep. 1 second delay will improve lot of performance.

Prevent my console application from closing after a .Net.Timer starts

So I have this simple code:
static void Main(string[] args)
{
var timer = new Timer(0.5 * 60 * 1000); // 0.5 minutes times 60 seconds times 1000 miliseconds
timer.Elapsed += new System.Timers.ElapsedEventHandler(Start);
timer.AutoReset = true;
timer.Start();
}
Which starts a timer that starts the whole program logic. Problem is, the console application closes and nothing is done. How do I prevent this? I know that if I do something like while(true) it works, but that does not seem like an elegant/proper solution.

Maybe try
Console.Read();
At the end of the code
Thanks to this your console window will not be closed as long as a user will not press a key.

The last answer is 7 years old. In the meantime, methods from System.Threading like Timer, Sleep, ...
should not be used anymore. They carry the risk of deadlocks, and I have to warn against their use especially in ASP.NET Core.
There are several things to consider:
No program runs forever. What happens when the program should be closed (by a shutdown or a signal)?
The termination must be implemented in your program logic. Many async .NET Core methods supports a CancellationToken as a parameter.
There are 2 approaches to create an "endless" program:
Worker Services in .NET Core are the common approach today to write programs that should run permanently as a service. They can be registered as Windows Service.
More Infos on learn.microsoft.com and devblogs.microsoft.com if you want to register your service as a "real" service.
If you need a "real" console application that performs tasks in the foreground, this can be done with the following sample code:
using System;
using System.Threading.Tasks;
using System.Threading;
namespace DemoApp
{
internal class Program
{
private static int _isRunning = 0;
private static async Task Main(string[] args)
{
// No program can run infinitely. We always have to provide a mechanism for termination.
var tcs = new CancellationTokenSource();
var periodTimeSpan = TimeSpan.FromSeconds(10);
// This mechanism is CTRL+C, so we catch this.
Console.CancelKeyPress += (sender, e) =>
{
tcs.Cancel();
e.Cancel = true;
};
try
{
// No endless loop. We are checking for a cancellation request!
while (!tcs.IsCancellationRequested)
{
// Perform your work.
var task1 = Run(tcs.Token);
var task2 = Task.Delay(periodTimeSpan, tcs.Token);
// If the execution time of Run is greater than periodTimeSpan, we will wait. Depends on your needs.
await Task.WhenAll(task1, task2);
}
}
catch (TaskCanceledException)
{
Console.WriteLine("User canceled your app.");
}
}
private static async Task Run(CancellationToken token)
{
// Should never occur if you use WhenAll()
if (Interlocked.Exchange(ref _isRunning, 1) == 0)
{
// Perform your work.
_isRunning = 0;
}
}
}
}

Add a Console.ReadKey(); this will allow you to close the console window by pressing any key.
static void Main(string[] args)
{
var timer = new Timer(0.5 * 60 * 1000); // 0.5 minutes times 60 seconds times 1000 miliseconds
timer.Elapsed += new System.Timers.ElapsedEventHandler(Start);
timer.AutoReset = true;
timer.Start();
Console.ReadKey();
}

If you want to just run a timer and wait, then Console.Read() is your friend.
The reason why your code is terminating is because the function initializes the timer, starts it and then ... hits the end of the Main function. As a result, the function exits.
The current code doesn't do anything useful (besides starting a timer which is ignored).
If you want to see your timer in action, do some other work after you start the timer. Then, stop the timer after an interval and print it/evaluate it how you deem fit. (The timer doesn't run on the main thread, whereas something like Console.Read() will be on the main thread and thus, block the thread until you have input)

Your console application does not end because the timer starts. It ends because the program reaches the end of the Main() method.
Whatever action you take to prevent the program from exiting Main() will help. While many proposed solutions actually do this. I wanted to highlight the fact that it's not the timer causing the issue.

How to close a console application within the specified number of hours?

I was tasked to append a timer within my working console app to let it close automatically after some time without requiring a user input.
My application has functions that delete certain data in the database based on some conditions and exits everytime the user inputs 'exit'.
Now the requirement is to automatically stop the process even if the deleting of items is not yet done given that the time set to close the application is provided, say 2 hours.
Can someone help me?
Thanks.

You can create a System.Timers.Timer with an interval of TimeSpan.FromHours(2) and call Environment.Exit() in its Elapsed handler.

I don't believe that killing the program is a good idea since you are manipulating data in a database but I think would be the simplest way to do it.
using Timer = System.Threading.Timer;
class Program
{
private static readonly Timer _timer =
new Timer(o => Environment.Exit(0), null, 5000, Timeout.Infinite);
static void Main(string[] args)
{
Console.ReadLine();
}
}

1) create a timer
2) set interval and the elapsed event handler
3) enable the timer for run
when timer triggers in the method hooked to the event just exit the application

If you are deleting data from database then stopping it Abruptly could be catastrophic. So you can implement somthing like this.
Perform the time consuming operation in a BackGroundWorker
Implement a Timer as explained in other examples.
Then when the Tick/Interval Event is raised Request the BackgroundWorker to Cancel the Task.
In your Do Work code Listen for this Cancel request and stop the deletion process safely(Either the Do Deletion or Don't Perform the it At all)
Then Use Environment.Exit() to exit out of the program.
Hope it helps

I solved this problem by having an app.config file where there is a value for key="Stoptime".
I then added a condition that checks the current time against the set end time. Following is an example solution (for those having the same problem):
public static void Main(string[] args)
{
string stoptime = ConfigurationManager.AppSettings["Stoptime"];
DateTime timeEnd = Convert.ToDateTime(stoptime);
today = DateTime.Now;
Console.WriteLine(today);
for (int i = 0; i < 100000; i++)
{
id.Add(i.ToString());
}
foreach(string item in id)
{
today = DateTime.Now;
if (timeEnd.CompareTo(today) >= 0)
{
Console.CursorLeft = 0;
Console.Write(item + " " + today);
}
else
{
Console.WriteLine();
Console.WriteLine("break.");
break;
}
}
Console.ReadKey();
}