timer1= new System.Windows.Forms.Timer();
timer1.Interval =60000; // 1 min
timer1.Start();
MyMethodName();
timer1.Stop();
MyMethodName()
-has a for loop for 90,000 entries (and some validations inside that for loop).
for (int i = 0; i <= 90000; i++)
{
//validations go here
}
When the time in timer1 is done for a minute, i want to stop executing other entries in the for loop.
For example, if 45,000 entries are done in a minute, i want to stop executing the method ie. stop the method after a minute.
However the above timer code, executes till all the 90000 records are done looping inside the for loop, somehow the method doesn't run for a minute? Any help?
Two things. Firstly Your timer code is not actually connected to the running of MyMethodName. A timer is designed to run processes when the time has elapsed (and possibly at regular intervals depending on how it is set up.
Secondly and more to the point of your question to abort a loop you have to put code inside the loop. The key would be to have a stopwatch or similar start before your loop and then at the beginning of your loop check how much time has elapsed. If it is a minute or more then break;.
The key thing to note is that you will not stop exactly on a minute but you will finish the iteration of the loop that is running when the minute expires and then stop. This is usually what you want since stopping processing midway through something may cause nasty side effects.
Stopwatch stopwatch = new Stopwatch();
stopwatch.Start();
for (int i =0; i<=90000; i++)
{
if (stopwatch.Elapsed>TimeSpan.FromSeconds(5))
break;
Console.WriteLine(i);
Thread.Sleep(1000);
}
Note that Thread.Sleep is there just because otherwise I get through all 90000 iterations too quickly. ;-)
So you would likely need a much different implementation. Consider this:
public class MyForm
{
private BackgroundWorker _worker;
public MyForm()
{
_worker = new BackgroundWorker();
_worker.DoWork += (s, args) =>
{
var timer = Stopwatch().StartNew();
do
{
// do something
} while (timer.ElapsedMilliseconds < 60000)
};
}
}
and then when you want to run it:
_worker.RunWorkerAsync();
However, you could make it even more robust. You could pass the time in like this:
_worker.RunWorkerAsync(60000);
and then in the DoWork handler, do this:
while (timer.ElapsedMilliseconds < (int)args.Argument)
Further, with the BackgroundWorker, you could support cancellation. Just set the WorkerSupportsCancellation flag to true and then in the condition do this:
while (timer.ElapsedMilliseconds < (int)args.Argument && !_worker.CancellationPending)
so, if necessary, you could do this:
_worker.CancelAsync();
Hmm, use a stopwatch instead
Stopwatch stopWatch = new Stopwatch();
stopWatch.Start();
for(int i= 0; i <= 90000; i++)
{
// Get the elapsed time as a TimeSpan value.
TimeSpan ts = stopWatch.Elapsed;
if(ts.Seconds >= 60)
break;
}
However the above timer code, executes till all the 90000 records are done looping inside the for loop, somehow the method doesn't run for a minute? Any help?
The timer will not raise events until you free up the UI thread, which won't occur until after the method completes fully.
If you want to prevent the method from running past a specific duration, you could handle it in your method directly:
MyMethodName(TimeSpan.FromMinutes(1));
Then, in your method:
void MyMethodName(TimeSpan maxRuntime)
{
DateTime expiration = DateTime.Now + maxRuntime;
for (int i = 0; i <= 90000; i++)
{
//validations go here
if (i % 100 == 0) // check every 100?
{
if (DateTime.Now > expiration)
break;
}
}
}
That being said, a better approach would be to push this into a background thread, and cancel as needed.
you can set a flag on in validations to see if it is done or not by hooking up an event handler to the Tick event in the Timer object
//in an area accessible to
//both elements
object readonly _lock = new object();
bool elapsed = false;
where your original code was
elapsed = false;
timer1= new System.Windows.Forms.Timer();
timer1.Interval =60000; // 1 min
timer1.Tick=((sender, everntArgs)=>
{
lock(_lock)
elapsed = true;
});
timer1.Start();
MyMethodName();
timer1.Stop();
Inside of MyMethodName
//inside the loop
for (int i = 0; i <= 90000; i++)
{
//validations go here
lock(_lock)
if(elapsed)
break;
}
If you use a CancellationTokenSource with the CancellationTokenSource(TimeSpan) constructor, it makes it easy to write a method that will cancel an action after a specified time.
You can write a method like so:
public static void RunTimedAction(Action<CancellationToken> action, TimeSpan timeout)
{
using (var cancellationTokenSource = new CancellationTokenSource(timeout))
action(cancellationTokenSource.Token);
}
And then you can write any action that takes a CancellationToken as a parameter, like this:
private void action(CancellationToken cancel)
{
int i;
for (i = 0; i < 1000000; ++i)
{
if (cancel.IsCancellationRequested)
break;
Thread.Sleep(10); // Simulate work.
}
Console.WriteLine("action() reached " + i);
}
Which you can use like this:
Console.WriteLine("Started at " + DateTime.Now);
RunTimedAction(action, TimeSpan.FromSeconds(10));
Console.WriteLine("Stopped at " + DateTime.Now);
Let's put this together into a complete demo program:
using System;
using System.Threading;
namespace Demo
{
class Program
{
void run()
{
Console.WriteLine("Started at " + DateTime.Now);
RunTimedAction(action, TimeSpan.FromSeconds(10));
Console.WriteLine("Stopped at " + DateTime.Now);
}
private void action(CancellationToken cancel)
{
int i;
for (i = 0; i < 1000000; ++i)
{
if (cancel.IsCancellationRequested)
break;
Thread.Sleep(10); // Simulate work.
}
Console.WriteLine("action() reached " + i);
}
public static void RunTimedAction(Action<CancellationToken> action, TimeSpan timeout)
{
using (var cancellationTokenSource = new CancellationTokenSource(timeout))
action(cancellationTokenSource.Token);
}
static void Main()
{
new Program().run();
}
}
}
Related
I am trying to refresh my frame every 17ms with a timer.
Timer timer = new Timer(17);
timer.Elapsed += ResetFrame;
timer.Start();
But instead of waiting for 17ms and then repeating, it waited for the frame refresh to complete and then wait for 17msfor the next repeat. This causes the frame to be refreshed every 28ms. How to synchronize it with real time?
To have a real time timer having a very short interval, you can take a look at this article:
Real Time Timer in C#
In Dot Net, following timers are not real time.
System.Windows.Forms.Timer
System.Timers.Timer
System.Threading.Timer
Means if you want to run your code at every 100 millisecond then above
timer fire even around 110 millisecond or later. Windows is not a real
time OS because of this .Net is also not a real time.
To create a real time timer in C# you have to write custom code that
can hold CPU to run your code at right time.
class Program
{
static void Main(string[] args)
{
Console.ReadLine();
Console.WriteLine("Running");
RealTimeTimerTest obj = new RealTimeTimerTest();
obj.Run();
}
}
public class RealTimeTimerTest
{
List<DateTime> lst = new List<DateTime>();
System.Diagnostics.Stopwatch sw = new System.Diagnostics.Stopwatch();
public void Run()
{
int Tick = 100;
int Sleep = Tick - 20;
long OldElapsedMilliseconds = 0;
sw.Start();
while (sw.IsRunning)
{
long ElapsedMilliseconds = sw.ElapsedMilliseconds;
long mod = (ElapsedMilliseconds % Tick);
if (OldElapsedMilliseconds != ElapsedMilliseconds && (mod == 0 || ElapsedMilliseconds > Tick))
{
//-----------------Do here whatever you want to do--------------Start
lst.Add(DateTime.Now);
//-----------------Do here whatever you want to do--------------End
//-----------------Restart----------------Start
OldElapsedMilliseconds = ElapsedMilliseconds;
OldElapsedMilliseconds = 0;
sw.Reset();
sw.Start();
System.Threading.Thread.Sleep(Sleep);
//-----------------Restart----------------End
}
//------------Must define some condition to break the loop here-----------Start
if (lst.Count > 500)
{
Write();
break;
}
//-------------Must define some condition to break the loop here-----------End
}
}
private void Write()
{
System.IO.StreamWriter sw = new System.IO.StreamWriter("d:\\text.txt", true);
foreach (DateTime dtStart in lst)
sw.WriteLine(dtStart.ToString("HH:mm:ss.ffffff")); sw.Close();
}
}
Also that:
Most accurate timer in .NET?
High resolution timer
High resolution timer in C#
Microsecond and Millisecond C# Timer
Precision-Repeat-Action-On-Interval-Async-Method
I'm working on windows service and I want to call a method from OnStart every minute. I originally had a forever while loop but then the service wouldn't install.
while (true)
{
Stopwatch stopWatch = new Stopwatch();
int totalTime = 0;
stopWatch.Start();
MethodToCall();
stopWatch.Stop();
// Get the elapsed time as a TimeSpan value.
TimeSpan ts = stopWatch.Elapsed;
totalTime = ts.Seconds * 1000 + ts.Milliseconds;
if (totalTime < 60000)
{
Thread.Sleep(60000 - totalTime);
//ManualResetEvent.WaitOne(10000);
}
else
{
Thread.Sleep(30000);
}
}
So, how can I make my method call every minute BUT when the method exceeds one minute it will wait N number of minutes(let's say 30 seconds) and then start over by calling the method.
Something like this should work. With the AutoReset flag set to false, the timer will only fire once, after the specified interval time. In the finally block, we make sure to restart the timer countdown, waiting for the interval to elapse again.
var interval = TimeSpan.FromMinutes( 1 );
var timer = new System.Timers.Timer( interval.TotalMilliseconds ) { AutoReset = false };
timer.Elapsed += ( sender, eventArgs ) =>
{
var start = DateTime.Now;
try
{
// do work
}
finally
{
var elapsed = DateTime.Now - start;
if ( elapsed < interval )
timer.Interval = (interval - elapsed).TotalMilliseconds;
else
timer.Interval = TimeSpan.FromSeconds( 30 ).TotalMilliseconds;
timer.Start();
}
};
timer.Start();
Source for Timer.Elapsed (note the bit about setting Interval resetting the countdown)
There are two solutions depending on what you want. Do you want to do work once a minute on the minute and always wait for the next minute? Or do you want to run no more than once a minute but it's okay to "catch up" if you fall behind?
In other words, if processing takes 80 seconds then does the next work start immediately or wait until T=120?
The first is easier, but note that I haven't tested this and it's just a guideline:
AutoResetEvent waitHandle = new AutoResetEvent(false);
System.Timer(() => waitHandle.Set(), null, TimeSpan.FromMinutes(1), TimeSpan.FromMilliseconds(-1));
while (true)
{
// Do stuff
waitHandle.WaitOne();
}
The second is just a bit harder.
ManualResetEvent waitHandle = new ManualResetEvent (false);
System.Timer(() => waitHandle.Set(), null, TimeSpan.FromMinutes(1), TimeSpan.FromMilliseconds(-1));
while (true)
{
// Do stuff
waitHandle.Reset();
waitHandle.WaitOne();
}
I am simulating a machine reading a Heart Beat. If the "user's" heart rate is within the accepted range, the app will sleep for 5 seconds then read again.
If the "user's" heart rate is outside the range then a countdown begins, leading to an end message.
I would like to be able to have a user interrupt the automatic countdown and restart the process
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading;
namespace Random_pulse
{
class Program
{
static void Main(string[] args)
{
Random rnd = new Random();
int j = 1;
int timeRemaining=10;
do
{
int pulse = rnd.Next(0, 200);
Console.WriteLine(pulse);
if (pulse > 50 && pulse <= 190)
{
Thread.Sleep(5000);
}
else if (pulse <= 50 && pulse > 0 || pulse > 190)
{
for (int i = 0; i < 10; i++)
{
Thread.Sleep(1000);
Console.WriteLine(timeRemaining--);
Console.Beep();
if (timeRemaining == 0)
{
Console.WriteLine("Alert sent!!");
j = 0;
}
}
}
else
{
Console.WriteLine("Alert sent!!");
j = 0;
}
}
while (j>0);
}
}
}
Rather than have the main thread sleep you could use a System.Timers.timer. Then use the main thread to start and stop the timer with input from the user.
Here's an example of the syntax. This is a timer that elapses continuously every 1 sec. OnTimedEvent would be your method of what you want to do.
System.Timers.Timer timer = new System.Timers.Timer(1000)();
timer.Elapsed += new ElapsedEventHandler(OnTimedEvent);
timer.Start();
If you need to pass arguments to your method you will need to use a lamda expression. For example:
timer.Elapsed += new ElapsedEventHandler(() => OnTimedEvent(arg1,arg2));
So your OnTimedEvent method may look like this:
private void OnTimedEvent()
{
int pulse = rnd.Next(0, 200);
Console.WriteLine(pulse);
if (pulse > 50 && pulse <= 190)
{
Thread.Sleep(5000);
}
else if (pulse <= 50 && pulse > 0 || pulse > 190)
{
for (int i = 0; i < 10; i++)
{
Thread.Sleep(1000);
Console.WriteLine(timeRemaining--);
Console.Beep();
if (timeRemaining == 0)
{
Console.WriteLine("Alert sent!!");
j = 0;
}
}
}
else
{
Console.WriteLine("Alert sent!!");
j = 0;
}
}
Use the timer to countdown. And set the input key to restart the timer or process you want. Thread sleeping is not the way to perform countdown.
You can use keydown event, and can reset the timer in that event.
To keep your solution simple, I'd suggest that you use a flag, say IsCancelled, which can be set by the user. After each 1 second interval, read the flag to check if the user has requested cancellation and break out of the for loop if the flag is true. Since your time interval is just 1 second, this might be an acceptable solution.
However, if you want true asynchrony, you can create a Task for sending alerts and cancel them using the CancellationTokenSource class. In fact, the example on the msdn link is pretty close to what your are doing.
If you use a Task object, you'd have to 'Wait' on the task to get completed/cancelled in your 'else if' condition before continuing with the while loop. Seems to be a much complex solution for your problem. But this is a very interesting challenge and you'd learn a lot about asynchronous programming in C#.
I have this code:
public void replay() {
long previous = DateTime.Now.Ticks;
for (int i = 0; i < 1000; i++) {
Thread.Sleep(300);
long cur = DateTime.Now.Ticks;
Console.WriteLine(cur - previous);
previous = cur;
}
}
Which is invoked as a separate thread like this:
MethodInvoker replayer = new MethodInvoker(replay);
replayer.BeginInvoke(null, null);
However, if I watch the output, it acts strangely. It outputs i in pairs. For example, it'll wait a full wait, then output i, then quickly output the next i too, then wait again. Why is it doing that and how can I correct it?
It outputs this:
3125040
2968788
2968788
2968788
3125040
2968788
2968788
2968788
3125040
2968788
2968788
2968788
3125040
If I increase the sleep to more than a second this doesn't happen.
Change the code to eliminate display latency in your analysis:
public void replay()
{
Thread.Sleep(5000);
DateTime start = DateTime.Now;
for (int i = 0; i < 1000; i++)
{
Console.WriteLine(string.Format("Exec:{0} - {1} ms",
i, DateTime.Now - start));
start = DateTime.Now;
Thread.Sleep(300);
}
}
Looking at your modified output, there is less than 5% variance (15ms out of the 300) in the loop delay. This is normal, due to the uncertainties involved in when the OS actually assigns timeslices to the thread... (If I recall correctly, in a windows OS, this is normally only every 20 ms !)
The larger discrepancy you perceive in the console output is almost certainly due to display latencys.
Cannot reproduce. I wonder if it is something local to your machine; buffering, perhaps.
I can't reproduce this, but you might want to consider a timer. It would be more reliable.
public class Counter
{
private readonly TimeSpan initialDelay, incrementDelay;
private readonly int maxCount;
private Timer timer;
private int count;
public Counter(TimeSpan initialDelay, TimeSpan incrementDelay, int maxCount)
{
this.maxCount = maxCount;
this.initialDelay = initialDelay;
this.incrementDelay = incrementDelay;
}
public void Start(Action<int> tickBehavior)
{
if (timer != null)
{
Timer temp = timer;
timer = null;
temp.Dispose();
}
timer = new Timer(() =>
{
tickBehavior(count++);
if (count > maxCount) timer.Dispose();
}, null, initialDelay, incrementDelay);
}
}
Use it:
Counter counter = new Counter(TimeSpan.FromSeconds(5), TimeSpan.FromSeconds(.3), 1000);
counter.Start((count) => Console.WriteLine(count););
EDIT
I'm using System.Threading.Timer, but Counter could be easily be modified to use System.Timers.Timer or System.Windows.Forms.Timer depending on your need. See this link for a description of when to use which timers.
Your sleep inside the loop is only 300ms, which isn't very long. You application will do the following:
Sleep 5 secs
print 0
Sleep 300ms
print 1
Sleep 300ms
print 2
etc.
I'm running into a common pattern in the code that I'm writing, where I need to wait for all threads in a group to complete, with a timeout. The timeout is supposed to be the time required for all threads to complete, so simply doing Thread.Join(timeout) for each thread won't work, since the possible timeout is then timeout * numThreads.
Right now I do something like the following:
var threadFinishEvents = new List<EventWaitHandle>();
foreach (DataObject data in dataList)
{
// Create local variables for the thread delegate
var threadFinish = new EventWaitHandle(false, EventResetMode.ManualReset);
threadFinishEvents.Add(threadFinish);
var localData = (DataObject) data.Clone();
var thread = new Thread(
delegate()
{
DoThreadStuff(localData);
threadFinish.Set();
}
);
thread.Start();
}
Mutex.WaitAll(threadFinishEvents.ToArray(), timeout);
However, it seems like there should be a simpler idiom for this sort of thing.
I still think using Join is simpler. Record the expected completion time (as Now+timeout), then, in a loop, do
if(!thread.Join(End-now))
throw new NotFinishedInTime();
With .NET 4.0 I find System.Threading.Tasks a lot easier to work with. Here's spin-wait loop which works reliably for me. It blocks the main thread until all the tasks complete. There's also Task.WaitAll, but that hasn't always worked for me.
for (int i = 0; i < N; i++)
{
tasks[i] = Task.Factory.StartNew(() =>
{
DoThreadStuff(localData);
});
}
while (tasks.Any(t => !t.IsCompleted)) { } //spin wait
This doesn't answer the question (no timeout), but I've made a very simple extension method to wait all threads of a collection:
using System.Collections.Generic;
using System.Threading;
namespace Extensions
{
public static class ThreadExtension
{
public static void WaitAll(this IEnumerable<Thread> threads)
{
if(threads!=null)
{
foreach(Thread thread in threads)
{ thread.Join(); }
}
}
}
}
Then you simply call:
List<Thread> threads=new List<Thread>();
//Add your threads to this collection
threads.WaitAll();
Since the question got bumped I will go ahead and post my solution.
using (var finished = new CountdownEvent(1))
{
for (DataObject data in dataList)
{
finished.AddCount();
var localData = (DataObject)data.Clone();
var thread = new Thread(
delegate()
{
try
{
DoThreadStuff(localData);
threadFinish.Set();
}
finally
{
finished.Signal();
}
}
);
thread.Start();
}
finished.Signal();
finished.Wait(YOUR_TIMEOUT);
}
Off the top of my head, why don't you just Thread.Join(timeout) and remove the time it took to join from the total timeout?
// pseudo-c#:
TimeSpan timeout = timeoutPerThread * threads.Count();
foreach (Thread thread in threads)
{
DateTime start = DateTime.Now;
if (!thread.Join(timeout))
throw new TimeoutException();
timeout -= (DateTime.Now - start);
}
Edit: code is now less pseudo. don't understand why you would mod an answer -2 when the answer you modded +4 is exactly the same, only less detailed.
This may not be an option for you, but if you can use the Parallel Extension for .NET then you could use Tasks instead of raw threads and then use Task.WaitAll() to wait for them to complete.
I read the book C# 4.0: The Complete Reference of Herbert Schildt. The author use join to give a solution :
class MyThread
{
public int Count;
public Thread Thrd;
public MyThread(string name)
{
Count = 0;
Thrd = new Thread(this.Run);
Thrd.Name = name;
Thrd.Start();
}
// Entry point of thread.
void Run()
{
Console.WriteLine(Thrd.Name + " starting.");
do
{
Thread.Sleep(500);
Console.WriteLine("In " + Thrd.Name +
", Count is " + Count);
Count++;
} while (Count < 10);
Console.WriteLine(Thrd.Name + " terminating.");
}
}
// Use Join() to wait for threads to end.
class JoinThreads
{
static void Main()
{
Console.WriteLine("Main thread starting.");
// Construct three threads.
MyThread mt1 = new MyThread("Child #1");
MyThread mt2 = new MyThread("Child #2");
MyThread mt3 = new MyThread("Child #3");
mt1.Thrd.Join();
Console.WriteLine("Child #1 joined.");
mt2.Thrd.Join();
Console.WriteLine("Child #2 joined.");
mt3.Thrd.Join();
Console.WriteLine("Child #3 joined.");
Console.WriteLine("Main thread ending.");
Console.ReadKey();
}
}
I was tying to figure out how to do this but i could not get any answers from google.
I know this is an old thread but here was my solution:
Use the following class:
class ThreadWaiter
{
private int _numThreads = 0;
private int _spinTime;
public ThreadWaiter(int SpinTime)
{
this._spinTime = SpinTime;
}
public void AddThreads(int numThreads)
{
_numThreads += numThreads;
}
public void RemoveThread()
{
if (_numThreads > 0)
{
_numThreads--;
}
}
public void Wait()
{
while (_numThreads != 0)
{
System.Threading.Thread.Sleep(_spinTime);
}
}
}
Call Addthreads(int numThreads) before executing a thread(s).
Call RemoveThread() after each one has completed.
Use Wait() at the point that you want to wait for all the threads to complete
before continuing
Possible solution:
var tasks = dataList
.Select(data => Task.Factory.StartNew(arg => DoThreadStuff(data), TaskContinuationOptions.LongRunning | TaskContinuationOptions.PreferFairness))
.ToArray();
var timeout = TimeSpan.FromMinutes(1);
Task.WaitAll(tasks, timeout);
Assuming dataList is the list of items and each item needs to be processed in a separate thread.
Here is an implementation inspired by Martin v. Löwis's answer:
/// <summary>
/// Blocks the calling thread until all threads terminate, or the specified
/// time elapses. Returns true if all threads terminated in time, or false if
/// at least one thread has not terminated after the specified amount of time
/// elapsed.
/// </summary>
public static bool JoinAll(IEnumerable<Thread> threads, TimeSpan timeout)
{
ArgumentNullException.ThrowIfNull(threads);
if (timeout < TimeSpan.Zero)
throw new ArgumentOutOfRangeException(nameof(timeout));
Stopwatch stopwatch = Stopwatch.StartNew();
foreach (Thread thread in threads)
{
if (!thread.IsAlive) continue;
TimeSpan remaining = timeout - stopwatch.Elapsed;
if (remaining < TimeSpan.Zero) return false;
if (!thread.Join(remaining)) return false;
}
return true;
}
For measuring the remaining time, instead of the DateTime.Now it uses a Stopwatch. The Stopwatch component is not sensitive to system-wide clock adjustments.
Usage example:
bool allTerminated = JoinAll(new[] { thread1, thread2 }, TimeSpan.FromSeconds(10));
The timeout must be a positive or zero TimeSpan. The Timeout.InfiniteTimeSpan constant is not supported.