C#•2y ago

❔ How to limit while loop updates per second amount

What i mean by the name is that: for a console application i'm developing (if you're wondering it's a game's server) i need a function something similar to say, Unity's FixedUpdate(), so that the function only happens somewhere like 50 times a second, because while (true) happens every single frame. or in layman's terms: How do i limit FPS?

85 Replies

Cattywampus•2y ago

you'd need to implement your own gameloop and no, while(true) and any other loops are NOT every frame even in Unity

Tvde1•2y ago

there is a PeriodicTimer which is pretty good. I don't know about it's accuracy though but it can be set to tick every X milliseconds it does not have the drift that a await Task.Delay(TimeSpan.FromMillisecond(20)) would have

Cattywampus•2y ago

in the context of gameloop I don' think this would be usable as is, you'd need to calc it based on display refresh rate to get 1 frame timing correctly

Jimmacle•2y ago

i have dealt with a lot of frustration regarding accurate game loop timing standard C# timers just aren't precise enough

ero•2y ago

they said it's a game's server

Jimmacle•2y ago

i haven't found a solution that minimizes drift without some amount of spin waiting

Cattywampus•2y ago

for frame-based engine, yeah you can't just do raw c#

ero•2y ago

that's what periodictimer does

RainysOP•2y ago

yeah, all it needs to do is send position data between the client and the server (the client is made in unity, so that's why i'm not that experienced in standalone application C# programming :D)

remmy_clarke_jr•2y ago

@Rainys What is your target OS? Does this need to run on Windows or Linux ?

Cattywampus•2y ago

so is this Unity or nah? you're trying to roll your own engine, right?

RainysOP•2y ago

windows is okay, but both would be nice i guess.

remmy_clarke_jr•2y ago

Each O/S has a specific mechanism for high resolution timers And XPlatform is a pain

RainysOP•2y ago

game (client) is made in unity, and the server is a standalone .NET console application, so to answer your question: no

Cattywampus•2y ago

wut?

remmy_clarke_jr•2y ago

@BadaBingBadaBoom ?

ero•2y ago

bogus lol

remmy_clarke_jr•2y ago

ero•2y ago

PeriodicTimer is cross platform it's the most precise and modern c# timer unity has its own stuff for handling server stuff, no? or like, there's dedicated libraries for it already

remmy_clarke_jr•2y ago

No PeriodicTimer still has performance and drift issues

ero•2y ago

prove it

remmy_clarke_jr•2y ago

I don't have too lol

ero•2y ago

you can't just make bogus claims without proof lmfao

remmy_clarke_jr•2y ago

But you're welcome to "mess about and find out" You're completely free to believe me or not Its the internet Everything i say could be false 😛

Cattywampus•2y ago

aight, you're trolling

ero•2y ago

if it wasn't obvious before

remmy_clarke_jr•2y ago

Wut

RainysOP•2y ago

i'm using a server system/framework or whatever you want to call it called Riptide. and all it basically does is allows the programmer to send "messages" between the clients and the server. However what should happen with the "messages" is all the programmer's work, but for now my question is what is the best way to implement the fixed update function thing in C# okay, so as i understand i should look into PeriodicTimer?

remmy_clarke_jr•2y ago

Wouldn't you be better off using an existing event system

ero•2y ago

it's pretty easy to use, too

remmy_clarke_jr•2y ago

What protocol does Unity push messages over?

Cattywampus•2y ago

Dude stop

ero•2y ago

like your whole program.cs is just like

PeriodicTimer timer = new(TimeSpan.FromSeconds(1d / 50d));

while (await timer.WaitForNextTickAsync())
{
  // code to execute on tick
}

PeriodicTimer timer = new(TimeSpan.FromSeconds(1d / 50d));

while (await timer.WaitForNextTickAsync())
{
  // code to execute on tick
}

RainysOP•2y ago

so this just executes the code inside the while loop 50 times every second?

ero•2y ago

yup

Jimmacle•2y ago

what's the drift on that loop?

RainysOP•2y ago

well, thanks, you answered my question :D

Jimmacle•2y ago

i recommend testing it to make sure the actual wait time doesn't vary too much

ero•2y ago

how should one check the drift, exactly?

Jimmacle•2y ago

with a stopwatch i haven't used this specific timer but every other timing mechanism i've tried has been awful for delays less than the length of an average game tick

ero•2y ago

come on, send some code i can test on

Jimmacle•2y ago

i'm about to leave for work which unfortunately isn't a game studio kek

ero•2y ago

no clue how this would be tested

Jimmacle•2y ago

just run a stopwatch in the loop and dump the wait time between ticks

ero•2y ago

no shot that's how you tested it LMFAO stopwatches are NOT accurate

Jimmacle•2y ago

they're more accurate than timers afaik

ero•2y ago

there's a reason we don't just use stopwatches to benchmark code

Jimmacle•2y ago

okay, what's used?

ero•2y ago

there's so much managed overhead to them BenchmarkDotNet? whatever they use

Jimmacle•2y ago

what does that use?

ero•2y ago

certainly not stopwatches lmao you can't get nanosecond accuracy with stopwatches

const double Interval = 1d / 50d;

PeriodicTimer timer = new(TimeSpan.FromSeconds(Interval));
DateTime dt = DateTime.Now;

while (await timer.WaitForNextTickAsync())
{
    dt = dt.AddSeconds(Interval);
    Console.WriteLine($"It is {dt}.");
}

const double Interval = 1d / 50d;

PeriodicTimer timer = new(TimeSpan.FromSeconds(Interval));
DateTime dt = DateTime.Now;

while (await timer.WaitForNextTickAsync())
{
    dt = dt.AddSeconds(Interval);
    Console.WriteLine($"It is {dt}.");
}

i just did this

Jimmacle•2y ago

you complain about stopwatches then you go and use datetime?

ero•2y ago

? surely trolling

Jimmacle•2y ago

wait, you aren't even timing

ero•2y ago

why would i

Jimmacle•2y ago

that's the point? to make sure the simulated time matches real world time

ero•2y ago

no? that's what that's doing it adds the supposed interval to the start time on each tick if there were a delay in the tick then the printed time would no longer match up with the real world time

Jimmacle•2y ago

where are you actually measuring time and not just adding a fixed number in that loop?

ero•2y ago

what's there to measure

Jimmacle•2y ago

you don't understand this assignment i gotta go to work

ero•2y ago

i think you just don't understand what that code accomplishes lol

Jimmacle•2y ago

you're assuming your timer is waiting as long as you tell it to which in my experience is never true especially with time spans this short the point is to verify it

ero•2y ago

how is this not verifying it if the loop runs for too long and the timer is delayed somehow

Jimmacle•2y ago

becuase you aren't comparing it with another timing mechanism sigh

ero•2y ago

??? i have a clock on my computer i'm comparing it to that

PeriodicTimer timer = new(TimeSpan.FromSeconds(1d / 50d));
Stopwatch sw = Stopwatch.StartNew();

while (await timer.WaitForNextTickAsync())
{
    sw.Stop();
    Console.WriteLine($"{sw.ElapsedMilliseconds}");
    sw.Restart();
}

PeriodicTimer timer = new(TimeSpan.FromSeconds(1d / 50d));
Stopwatch sw = Stopwatch.StartNew();

while (await timer.WaitForNextTickAsync())
{
    sw.Stop();
    Console.WriteLine($"{sw.ElapsedMilliseconds}");
    sw.Restart();
}

hell yeah, so much more accurate! 1 / 50 s is 20 ms by the way

Jimmacle•2y ago

i trust the stopwatch more than the timer

ero•2y ago

then you just don't know how these things work like period

Jimmacle•2y ago

you said you don't know how benchmarkdotnet actually times things so i guess we're in the same boat

ero•2y ago

strawman

Jimmacle•2y ago

that even gets the benefit of average time, you can't take the average here because jitter is an important metric for game loops

ero•2y ago

BDN uses Perfolizer.Horology.IClock and gets a completely custom clock depending on the target of the benchmark

Jimmacle•2y ago

using System.Diagnostics;

var timer = new PeriodicTimer(TimeSpan.FromMilliseconds(10));
var counter = 0;
var stopwatch = Stopwatch.StartNew();

while (counter < 1000)
{
    await timer.WaitForNextTickAsync();
    counter++;
}

stopwatch.Stop();
Console.WriteLine($"10 seconds in loop = {stopwatch.Elapsed.TotalSeconds}");

using System.Diagnostics;

var timer = new PeriodicTimer(TimeSpan.FromMilliseconds(10));
var counter = 0;
var stopwatch = Stopwatch.StartNew();

while (counter < 1000)
{
    await timer.WaitForNextTickAsync();
    counter++;
}

stopwatch.Stop();
Console.WriteLine($"10 seconds in loop = {stopwatch.Elapsed.TotalSeconds}");

10 seconds in loop = 10.9501011 so stopwatch is either very wrong or your timer consistently delays longer than intended

ero•2y ago

"my" timer lol

Jimmacle•2y ago

you're defending it ¯\_(ツ)_/¯ i'm just adding this to my list of timers that aren't accurate enough for game loop synchronization

ero•2y ago

ero•2y ago

couldn't be that stopwatch is wrong just impossible

Jimmacle•2y ago

so windows performance counters are off by 50%? on my system at least it reports stopwatch resolution to be 100ns which should be more than enough for this test practically every non-busy wait i have tried from timers to sleeps to delays all guarantee a minimum wait time, not an exact time and when you're having them fire every 10-20ms it adds up fast

ero•2y ago

in the end it's all hardware dependent i'm not so much "defending" the timer as i am defending my stance on not using stopwatch to measure anything ever that has too much overhead, no warming up, no optimization

Jimmacle•2y ago

i mean we can pick something else but i doubt it's off by over 50% that would be entirely unusable

ero•2y ago

this is on my work laptop. i'm sure we'd get another different result on my home pc

Jimmacle•2y ago

we got different results between us to begin with and i'm on my work pc 👀

ero•2y ago

i'm saying a third different result

Jimmacle•2y ago

we already have enough results to know something is significantly off

ero•2y ago

i was just saying man pepeW

Accord•2y ago

Was this issue resolved? If so, run /close - otherwise I will mark this as stale and this post will be archived until there is new activity.

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❔ How to limit while loop updates per second amount