C# program runs slowly on multiple instances

Question

Now a days I'm practicing some programs of C#. I have an issue in this program.

I have created this program and it took 21 seconds to execute and my CPU usage is 20% and Ram usage is 1Gb max.

1. static void Main(string[] args)
2. {
3. string str = Console.ReadLine();
5. if (str == "start")
6. {
7. // FrameRecord(40, 140, 780, 570, 2000, "E:\\imgCH1\\", 1);
9. Stopwatch sw = new Stopwatch();
10. for (int i = 1; i < 200000; i++)
11. {
12. sw.Start();
14. Console.WriteLine("Acccessed Value" + i.ToString());
15. Console.WriteLine("Time " + sw.ElapsedMilliseconds);
17. }
20. }
23. Console.Read();
24. }

but when I create 2 instances of this It took 140 seconds and CPU usage is 20 % and Ram usage is 1GB max.

Can you please help me, how can I run multiple instances which will take 21 seconds but can utilize my Ram and CPU as maximum.

Afzaal Ahmad Zeeshan · Answer

Hello Sachin I am impressed by the fact that you learning how C# programs actually work. But you missed quite a few things let me list them all for you first Every program gets a share in CPU RAM and other resources. C# programs have a single thread. More instances mean more threads to work on. (This moves into the world of parallelism) Other programs are also working and they need some CPU time. Whenever they execute your program will remain idle -- that counts too. Now to explain these points to you let me go step by step. The first thing to understand in .NET framework is that you only get to program .NET framework not the underlying CPU RAM or any other hardware resource -- that is entirely the purpose of .NET framework. If you run an application it won't be the only application using CPU there are other programs threads and services that require some CPU too. They will be provided some CPU time too. Thus 21 seconds for 200000 iterations is still way too much. In most cases (just for I/O to console) it just takes 1-5 seconds. Which makes me think your CPU is not powerful enough. Sorry. Your code is very poorly written let me show you Stopwatch sw = new Stopwatch(); for ( int i = 1; i { sw.Start(); // Why are you starting the Stopwatch again and again 200000 times? Is that a good approach? Consider this Stopwatch sw = new Stopwatch(); sw.Start(); // Do the work. for ( int i = 1; i { Console.WriteLine( Acccessed Value + i.ToString()); } // After the iterations stop and access the time. sw.Stop(); Console.WriteLine( Time  + sw.ElapsedMilliseconds); Now this will work in a much better way and will only start the watch once and at the end will stop it and access the elapsed time. Finally it is not your program that decides how much CPU or RAM it requires instead it is the .NET framework that decides this... One of the major factor toward accessing multiple CPU cores or accessing the full CPU limit is by having multiple threads running. As for the timing you can see the following thread to see that this minimal program would never take that much time; https://dotnetfiddle.net/RoQcZX. I hope my answer clears most of the confusions in your mind.

Bikesh Srivastava · Answer

Yes definatly you are doing bad practice loop will take more time so change logic.