Question

I need to induce a variable amount of lag in vb.net. System should be noticeably slower.

I can raise the CPU usage of the program with infinite loops and some variable creation/assignments, but how can I actually cause lag?

I understand this is an odd request, but I appreciate any help and would appreciate it being taken seriously. This is NOT being used maliciously.

I’d like to have an “InvokeLag” sub which will perform an action to slow down the computer, the faster the function is called the faster it lags. The function should be as mundane as possible, not modifying anything or doing anything to cause damage other than simple lag.

Thanks for your help!

EDIT: Preferably only achieving this effect with crazy math operations and making variables and such. Nothing system if possible.

Answer 1

What about creating a new thread with the highest priority? Calculating Pi will never end and with a high priority it should lag your system down. If you have several processors you could start several threads to calculate pi or have a separate program that calculates pi and start several processes of it?

Public Class Test
    Shared Sub Main()

        Dim threadLag As Thread = _
            New Thread(AddressOf CalculatePi)
        threadLag.Name = "ThreadWait"
        threadLag.Priority = ThreadPriority.Highest
        threadLag.Start()
    End Sub

    Private Sub LagRoutine()
        While True
            Thread.SpinWait(10000)
        End While
    End Sub

End Class

or

Public Class Test
    Shared Sub Main()
        For i as Integer = 1 to 10
             Dim p As New Process("C:\MyLagProgram.exe")
             p.Start()
        Next i
    End Sub

End Class

CalculatePi

MSDN

Update:

I think Eric might have a good point about SpinWait and it might be more what you are looking for:

The SpinWait method is useful for
implementing locks. Classes in the
.NET Framework, such as Monitor and
ReaderWriterLock, use this method
internally. SpinWait essentially puts
the processor into a very tight loop,
with the loop count specified by the
iterations parameter. The duration of
the wait therefore depends on the
speed of the processor.

Contrast this with the Sleep method. A
thread that calls Sleep yields the
rest of its current slice of processor
time, even if the specified interval
is zero. Specifying a non-zero
interval for Sleep removes the thread
from consideration by the thread
scheduler until the time interval has
elapsed.

There is no System IO, its basically just a tight loop which does not give up its processing time. I am sure if you used my suggestion of spawning several threads with the highest priority with Eric’s suggestion SpinWait you would achieve what you are looking for. This would also reduce the amount of code you would need to write.