Why are .NET timers slow, even on 1ms interval???

[Wokawidget]

In VB6 if I have a timer to move a form:

mfrmForm.Left = mfrmForm.Left + 1

...and I set the interval of the timer to 1, then the form flys off the screen. VERY fast.

If I do the same in .NET then it moves slowly...not THAT slowly...but slower than a form in VB6 would if the timer was set to 30ms!

I have used standard timer, and the component timer, but this has not made any difference.

Any ideas?

Woka

[seidel1]

Could you show me all the code for this? I would like to try it.

Jim

[Wokawidget]

Private mfrmNew As New Form2
 
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        mfrmNew.Show()
        Timer2.Enabled = True
    End Sub
 
    Private Sub Timer1_Tick(ByVal sender As System.Object, ByVal e As System.EventArgs)
        'This is a normal timer
        mfrmNew.Top = mfrmNew.Top - 1
    End Sub
 
    Private Sub Timer2_Elapsed(ByVal sender As System.Object, ByVal e As System.Timers.ElapsedEventArgs) Handles Timer2.Elapsed
        'This is a component timer
        mfrmNew.Top = mfrmNew.Top - 1
    End Sub

Hope that helps.

Woka

[Jacob Roman]

Never use Timers, especially in .NET. Timers are horribly slow, inaccurate, inconsistant, and not real time. Use managed loops such as Do Loops, only with frame limiting API's, such as QueryPerformanceCounter, QueryPerformanceFrequency, GetTickCount, etc. If done correctly, it'll run in real time.

[mendhak]

This is a class used during one of the early Forum Contests. Try it:

Imports System
Imports System.Runtime.InteropServices
 
Namespace Org.Mentalis.Utilities
    
    Public NotInheritable Class StopWatch
        Private m_StartTime As Long
        Private m_Frequency As Long
        Private Declare Ansi Function QueryPerformanceCounter Lib "kernel32.dll" (ByRef x As Long) As Integer
         Private Declare Ansi Function QueryPerformanceFrequency Lib "kernel32.dll" (ByRef x As Long) As Integer
         Public Sub New()
            Frequency = GetFrequency()
            Reset()
        End Sub
       Public Sub Reset()
            StartTime = GetValue()
        End Sub
        Public Function Peek() As Long
            Return CType((((GetValue() - StartTime) / CType(Frequency, Double)) * 10000), Long)
        End Function
        Private Function GetValue() As Long
            Dim ret As Long = 0
            If QueryPerformanceCounter(ret) = 0 Then Throw New NotSupportedException("Error while querying the high-resolution performance counter.")
            Return ret
        End Function
        Private Function GetFrequency() As Long
            Dim ret As Long = 0
            If QueryPerformanceFrequency(ret) = 0 Then Throw New NotSupportedException("Error while querying the performance counter frequency.")
            Return ret
        End Function
         Private Property StartTime() As Long
            Get
                Return m_StartTime
            End Get
            Set(ByVal Value As Long)
                m_StartTime = Value
            End Set
        End Property
        Private Property Frequency() As Long
            Get
                Return m_Frequency
            End Get
            Set(ByVal Value As Long)
                m_Frequency = Value
            End Set
        End Property
        
    End Class
End Namespace

[Indigo7]

I am having a similar problem. I have come up with somewhat of a fix by writing my own timer class which runs in its own thread, using the stopwatch class referred to above. The thread runs in this sub:

Private Sub timerTicker()
        While True
            stopwatch.Reset()
            While (stopwatch.Peek / CType(10, Single) < _interval)
                Thread.Sleep(_sleepInt)
            End While
            RaiseEvent Tick()
        End While
    End Sub

The problem with this code is, even if _sleepInt is set to 1, the actual delay is 15.4ms or so. If sleepInt is 0, the timer is very accurate, but then the cpu usage is 100%. Both are unacceptable. Is there any other way besides thread.sleep to take a burden off the cpu which won't compromise my interval accuracy?