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.
Related
As far as I know single .net application can allocate a lot from available memory. It will be released by GC at some point. I never have to care much about details. It just works.
But what is going to happen if native application is started while most/all memory is used by .net application? Will GC respects this and free memory before? Or will Windows "take care" and will swap memory of .net appplication into swap-file?
I have a single PC with slow HDD, where my WPF application (MVVM, bitmaps, database, pretty memory-intensive) occupy 200-2000 Mb (up to 80%) of RAM and I get reports what PC become slow when running Office, antivirus, etc.
In e.g. Photoshop there is a setting to limit amount of used RAM. Now I am thinking whenever such thing make sense in my WPF application.
Is uncontrollable GC memory allocation a problem or not? Should I limit amount of used by my application memory?
The problem described does not look related to .NET memory management/GC, assuming that application just holds the operation data (in use) in the memory.
.NET app is not different from any other user app so the OS will treat them in the same way: move infrequently used memory blocks to the swap file.
If the application occupies 80% of RAM and works with memory intensively, competing with other applications, the whole process will generate a lot of page faults causing large traffic between swap file and memory. This leads to severe performance degradation, especially in case of slow HDD.
The .NET part in this game is just to clean the application memory from time to time from the data no longer in use. If there are just big amount of data required for the app to run and just adding more RAM is not an option, then application redesign (which limits the amount of loaded data somehow) is a considerable approach.
I am working to diagnose a series of OutOfMemoryException problems within an application of ours. This is an internal 32-bit (x86) OWIN-hosted WebAPI that runs within a console application and talks to a series of hardware components in parallel. For that reason it's creating around 20 instances of a library, and the sharp increase in "virtual size" memory matches when those instances are created.
From the output of Process Explorer, and dotMemory, it does not appear that we're allocating that much actual memory within this application:
From reading many, many SO answers I think I understand that our problem is either from fragmentation within the G0, G1, G2 & LOH heaps, or we're possibly bumping into the 2GB addressable memory limit for a 32-bit process running on Windows 7. This application works in batches where it collects a bunch of data from hardware devices, creates collections in memory to aggregate that data into a single object, and then saves it to be retrieved by a client app. This activity is the cause of the spikes in the dotMemory visual, but these data structures are not enormous, which I think the dotMemory chart shows.
Looking at the heaps has shown they rarely grow beyond 10-15MB in size, and I don't see much evidence that the LOH is growing too large or being severely fragmented. I'm really struggling with how to proceed to better understand what's happening here.
So my question is two-fold:
Is it conceivable that we could be hitting that 2GB limit for virtual memory, and that's a cause for these memory exceptions?
If that is a possible cause then am I right in thinking a 64-bit build would get around that?
We are exploring moving to a 64-bit build, but that would require updating some low-level libraries we use to also be 64-bit. It's certainly an option we will explore eventually (if not sooner), but we're trying to understand this situation better before investing the time required.
Update after setting the LARGEADDRESSFLAG
Based a recommendation I set that flag on the binary and interestingly saw the virtual size jump immediately to nearly 3GB. I don't know if I should be alarmed by that?!
I will monitor the application with this configuration for the next several hours.
In my case the advice provided by #ThomasWeller was indeed correct and enabling the "large address aware" flag has allowed this application to run for several days without throwing memory exceptions.
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.