I have written a small WinForm application in C#. The EXE that is made is 74 Kb and all together with the resources and all it sizes 179 Kb. But when I run it, it takes 9.1 MBs in memory according to Task Manager.
So my question is:
Why is it happening?
What can I do to reduce the size of this?
If the size could be reduced how much reduction is possible?
Firstly, using Task Manager to determine memory usage is fraught with peril. Have a read of this article to gain a clearer understanding of it.
What other libraries are you referencing?
What files are you loading, into streams or any other way?
What resources do you request from the Operating System via P/Invoke
How many instances of each form do you load?
How many variables do you create, and of what size?
For example:
// Will take up a lot of memory!
var x = new byte[int.MaxValue];
All that said, 9.1Mb isn't really a lot (less than 0.5% of memory on a machine spec'd with 2Gb of RAM) and more importantly, does it actually matter that your application's using 9.1Mb of RAM, or are you wasting your time investigating? Remember, your time's valuable. Would your end users rather the time was spent on something else? =)
Size of executable and memory usage are two completely separate notions. For example this simple program:
class Program
{
static void Main()
{
var b = new byte[int.MaxValue];
}
}
is only 4KB but it uses all of the available RAM on your computer and crash. This is to demonstrate you that you could have an extremely simple application but depending on what it is doing it could consume lots of memory. So what is your application doing?
The memory usage of a program is not 100% related to the size of it's binary or resources.
It depends on what your program does. For example if you create something like this:
List<int> list = new List<int>();
for (i=1; i<100000; i++) list.Add(i);
It will take as much memory as it need to store int's plus it's object overhead.
And it depends on what usings you've used.
You've tagged your post with winforms - I assume you've got a gui app. Gui's memory usage depend on used controls and their gui style (e.g. animations, hover effects ...)
And .NET has a garbage collector which will free unused memory during runtime.
Related
I was wondering if it is possible for C# to write objects to the pagefile.
I already know that a virtual machine for a .NET application is limited to allow one object to only use up 2 GB of ram and will run out of Memory long before that - even on 64-bit version of Windows.
However I need to be able to load a huge amount of strings (not 1 big one but many small ones) and was wondering if it is possible to load them and let them be written to the swap space until they are needed again (unfortunately it is not possible for me to prevent the loading of all the strings because it is forced by an application calling the code I am working on).
To prototype it I tried out to see if the following program will run out of memory as well (which it will), even though it does not try to allocate one huge string:
public static void Main()
{
ICollection<StringBuilder> builders = new LinkedList<StringBuilder>();
double used_ram = 2*1024*1024*1024L;
int blocksize = 12800000;
int blocks = (int) (used_ram/blocksize);
for (int i = 1; i < blocks ; i++)
{
StringBuilder sb = new StringBuilder(blocksize/2);
builders.Add(sb);
}
Console.ReadLine();
}
I was hoping that the strings would be written to the swap space and was wondering if there is any way I can force the application to do just that.
EDIT: Changed the use of swap file to pagefile (thanks for the clarifications).
Ok so to enhance my question: if the only limitation of the runtime is that ONE object can not allocate more than 2 gb of memory - why is the above code running out of memory - because the list goes over the 2 gb of memory by holding reference to all the string builders?
Short answer: no you can't.
Using the swap is not something applications do: the memory management system of the operating system is responsible of that.
If you need to load more than 2GB of data in your process in one time (and not retrieve data from disk per chunks as necessary), then you have a serious design problem.
EDIT:
As you're already using a 64-bit OS, make sure you're compiling your application for x64 platforms (or AnyCPU) and your application is not running as a 32-bit process using WOW64.
I think your question amount to:
Can a 32 bit .NET application address more than 2GB of memory.
Yes, it is possible to increase the amount of memory that applications can address by adjusting the split between the memory allocated to user applications and the operating system but I would not recommend it in most cases as it can cause subtle and not so subtle problems with O/S functions, such as networking. For details on the /3GB and /USERVA switches please see this article. This will allow your application to address 3GB (minus overhead) of memory rather than 2GB.
Tools at your disposal are:
Switching to 64 bit .NET.
Using memory mapped files.
Writing your own paging system.
Using some backing store e.g. file system, database.
You can utilize all of the windows memory management functions and allocate as much memory as the system will allow, but what you are doing screams for some type of flush to disk system. Even if you could get windows to allocate that large an object you performance would be terrible. There are many out of the box system (called databases) which allow you to put large amounts of data in them and access them it very short order.
You may be doing something wrong. I've written .net applications that use way over 2 GB of memory. If you are running 64 bit windows, there's no reason your application shouldn't be able to use much more memory.
I recommend you should write your own Cache-Class. For an example have a look here
I think what cames closes to your approach on the .Net application level would be a MemoryMappedFile.
But this would mean the application wouldn't try to get all the strings in one go.
I wrote a hello world program (windows application without any UI) in C#. The release-build excutable doesn't do anything but to Thread.Sleep(50000) //50 seconds.
I opened sysinternals (a profiler like task manager). This excutable ate 7MB memory (private bytes)!!
Can anybody explain what is happening and how to make the memory usage smaller.
P.S. I also tried to use NGEN to pre-compile the .exe but still got the same memory usage.
Thanks a lot
C# (and other JIT compiled/interpreted languages) usually end up doing a lot of things for you automatically in the background. While what you've written is simple, there's a lot of stuff going on in the background to support the JIT nature of the application.
That 7MB of memory is relatively small given 2GB of RAM is fairly commonplace these days. And it probably won't go up more unless you do something unusual or allocate lots of arrays and data structures.
If it's a Hello World based on the C# WindowsApplication project type, and there's an int main in Program.cs doing an application.run on a Windows Form, then not only is there a lot of JIT overhead, but there's a lot of Windows Forms overhead too.
End of the day, I'm sure everything is dandy.
.Net apps have a lot of basic overhead, but your memory increase should be relatively small after that point.
Example. My one app consumes 10MB of memory on load, but it only consumes 40MB of memory after loading 60k rows from a Database, each row containing multiple strings and many values.
A small fixed upfront value isn't that bad, on modern computers. Scalability is the primary issue now-a-days. .Net scales fairly well for being managed.
I was hoping someone could explain why my application when loaded uses varying amounts of RAM. I'm speaking about a compiled version that uses the exe directly. It's a pretty basic applications and there are no conditional branches in the startup of the application. Yet every time I start it up the RAM amount varies from 6MB-16MB.
I know it's on the small end of usage anyways but I'm curious of why this happens.
Edit: to give a bit more clarification on what the app actually does.
It is a WinForm project.
It connects to a database using sqlclient to retrieve a list of servers.
Based on that list a series of buttons are created to start and stop a service on those servers.
Using the System.Timers class to audit the status of the services on those servers every 20 seconds.
The applications at this point sits there and waits for user input via one of the button clicks to start/stop the service.
The trick here is that the amount of RAM reported by the task schedule is not the amount of RAM used by your application. Rather, it is the amount of RAM reserved for use by your application.
Remember that with managed frameworks like .Net, you don't request or release memory directly. Rather, a garbage collector manages the memory for you. The amount of memory reserved for your application at a given time can vary and depends on a lot of different factors, including memory pressure created at the time by other programs.
Think of it this way: if you need 10 MBs of RAM for your app, is it faster to request and return it to the operating system 1 MB at a time over 10 requests/releases or reserve the block at once with one request/release? Now extend that to a scenario where you don't know exactly how much RAM you'll need, only that it's somewhere in the neighborhood of 10 MB. Additionally, your computer has 1 GB sitting there unused. Of course the best thing to do is take a good-sized chunk of that available RAM. Even 20 or 30 MB wouldn't be unreasonable relative to the ram that's sitting there unused, because unused RAM is wasted performance.
If your system later starts to feel some memory pressure then .Net can easily return some RAM to the system. This is one of the ways managed languages can sometimes give better performance than languages like C++ with traditional memory management: a garbage collector that can more easily take the entire system health into account when allocating memory.
What are you using to determine how much memory is being "used". Even with regular applications Windows will aggressively allocate unused memory in advance, with .NET applications it's even more complicated as to how much memory is actually being used, and how much Windows is just tacking on so that it will be available instantly when needed. If another application actually asks for memory this reserved memory will be repurposed.
One way to check is to minimize the application (at least on XP). If you are looking at the memory use in something like task manager you'll notice it drops off right away, eliminating the seemly "random" amount allocated.
It may be related to the jitter, after the first load the jitter already created a compiled version and it doesn't need to run. Other than that you would have to give us some more details about the app and which kind of memory you are referring to.
I am mostly curious and this isnt a problem. Typically my (C++) apps use very little memory. I thought my current app would take little memory but it uses 3.7mb and VM size of 17.3mb. The app has 4 icons in its resource file, 4 ints in the local(user)settings and is the app LoC is <1k. It detects keyinput and writes a line in a listbox when the user goes idle (calling a windows function). It put itself in the system tray and has a timer set to 100ms.
Theres no arrays or any storage except for a few structs that are less 256bytes together. Why is my app using 17mb+ of VM?
Because it's a managed application, a part of the CLR will also be loaded in memory. Also, the CLR will allocate a bunch of memory so that it may satisfy new object requests (it does not allocate each object from the system). There's also a bunch of other objects that get allocated for each application in a managed model (for instance the thread pool, the garbage collector, etc).
I'm not sure you can do much about reducing that, but on the flip side, you won't see it scale linearly with the app complexity (as in if you make it twice the complexity, it won't use twice the memory).
17 megs sounds about right for a simple C# app.
I guess its the perennial 'hardware use versus programmer productivity' argument.
Grab the .NET memory profiler if you care to see exactly what's taking up that memory.
Programs written with the .NET framework inherently have more overhead.
Something to bear in mind is that each managed thread has a 1MB stack, too. If you're doing anything with threads, that's a couple of MB right away.
Don't worry about memory consumption for a Hello World app.
A managed language app handles its memory usage differently than, say, C where every memory allocation has the risk of not being deallocated.
In some cases a .NET app may even run faster than an equivalent app written in C++ if the app spends a lot of time in malloc/dealloc because the CLR can put off deallocating/garbage collecting until when the app is idle.
I have developed a winforms application using C# in VS2008. When I run this application I observed in task manager that it shows 80 MB of memory is consumed.
How can I reduce this? Even very small applications also take 8 MB of memory...
What can I do to reduce the memory footprint?
Thank you very much in advance.
The task manager memory number is not always as sharp as it would be, however this small trick can cheat that number... Not meant for production
public static void RefreshMemory() {
try {
Process curProc = Process.GetCurrentProcess();
curProc.MaxWorkingSet = curProc.MaxWorkingSet;
} catch {
// Handle the exception
}
}
It would be helpful also to trace the memory objects usage with a tool like JetBrains dotTrace or another similar.
Your question clearly smells of premature optimization.
You should tackle memory usage only in the following situations :
You're developing for a device which hasn't a lot of memory available (with the portable .net framework for example)
You're reaching the limit of .net in term of memory size (ie around 1.3gbp)
Your customers are complaining.
Don't get me wrong, this doesn't mean you must waste memory or that you shouldn't take memory in consideration while coding. I just mean that in your case, memory usage is probably not a big deal.
Well, the .NET framework has a fairly significant overhead -- the simplest possible "hello world" console app has a 4 mb working set, as you have observed. There are a number of things you can do to reduce the memory footprint (reduce embedded resources, be sure to build in Release configuration, etc.)
But at the end of the day, .NET is designed for developer efficiency over memory/resource efficiency, so if you have an app that has to run in a very small efficient memory space you should consider writing it in C++ or some other language where you manage your own resources.
In addition to all the previous good comments, please remember that the numbers you are seeing in Task Manager are virtual memory, not physical memory. The actual amount of physical RAM used by the program is not obvious from looking at Task Manager. Also, Task Manager is showing you a series of snapshots - if you really had a problem, you'd want to look at it over time, with Perfmon or something, in addition to the excellent suggestion on profiling with JetBrains' dotTrace.
But don't do any optimization until your code works, and has high test coverage, and until you know what actually needs to be optimized. Otherwise, you run the risk of optimizing problems that don't exist, and worse, of optimizing the wrong problem, while ignoring the real problem or possibly making it worse.