I have seen this question before but the responses haven't scaled to my needs. I am looking for a way to analyze heap dumps from a C# application that uses an extremely high amount of memory.
One issue I run into is that the tool I am using is x86. This has been the case for a few appealing tools (VS2013 Ultimate, Antz memory profiler, PerfView).
I have also invested some time trying CLR Profiler but this does not seem to work (Edit - work when attached to the application).
Right now I feel my only other option would be to jump into Windbg. Are there any other tools that could support this?
Thanks!
I have used Windbg a lot. A DumpHeap -stat will give you good and fast results to check which objects are flooding over. If you are lucky you get from the call stacks a clue what is allocating so much data.
Personally I like PerfView much better because it is much faster (it samples the heaps) and stores in the .gcDump file only a fraction of the data needed from the dump. You can take with PerfView a heap snapshot and ship this to the HQ which is much smaller than the original dump (factor 100 smaller usually). I have analyzed up to 36 GB dumps with PerfView with some issues but Vance Morrison was kind enough to help me out to fix his heap traversal code where a Stackoverflow occured.
PerfView may be x86 but the internal HeapDumper which extracts the data from the dump is 64 bit of course.
An alternative approach without any dumps is to enable in PerfView .NET Heap Sampl alloc tracing. This way you get call stacks for all allocations leading you directly to the code where allocations are happening.
Related
I suspect my C# server app (running on win server 2012) has a native memory leak, likely from one of the native libraries I'm using. My app reaches ~2.5GB commited memory after running for about 2 weeks. Looking at a dump using WinDbg, I see 1.9GB of native memory (which keeps increasing). Managed memory did not increase beyond a ±600MB-ish threshold.
Running the !heap -s command I see that two segments take up 1.7GB of heap memory combined, however inspecting those segments with !heap -stat -h (basically following the flow from https://www.codeproject.com/Articles/31382/Memory-Leak-Detection-Using-Windbg) shows me that the amount of busy bytes combined for both is about 30MB, which leaves me with no idea on what could cause the leak.
I have no option of live debugging the app (connecting with a profiler etc) at the moment, since it is running in production and a performance degradation is out of question. Unfortunately, this behavior is also not reproducible in any other environment available to me.
One of my initial guesses was that this is not a leak but rather just lazy reclamation of memory by the OS (since no other process requires this memory). I could verify this by spinning up processes which eat up a lot of memory, but if I'm wrong my app would crash and that is not a good possibility for me :)
Is there any other way I can understand whats going on in the dump? Any other tool perhaps?
Any help would be greatly appreciated!
I have an app which consumes a lot of real time data, and because it's doing so much it's quite slow under the VS 2010 and this causes it to fail in various ways.
So I was wondering if there's any way other than this profiler that I can find out how much memory in bytes say is allocated to each type in memory and dump this out periodically?
It's quite a large application so adding my own counters isn't really feasible...
You need to use a memory profiler.
There are many around, some free and some commercial.
MemProfiler
ANTS memory profiler
dotTrace
clr profiler
Also see What Are Some Good .NET Profilers?
There is no easy general purpose way of saying GetBytesUsedForInstance(object), but it depends what you need the data for (unless all your types are value types, in which case it should be relatively simple).
We have an in memory cache for part of our application. We care most about relative amounts of memory used - ie the total cache size is twice what it was yesterday. For this, we serialize our object graphs to a stream and take the stream length (and then discard the stream). This is not an accurate measurement of "how much memory a type uses up" per se, but is useful for these relative comparisons.
Other than that - I think you are stuck using a profiler. I can highly recommend SciTech Memory Profiler - I use it a lot. It integrates well into Visual Studio, is fast (the latest version is anyway), and gives tremendously useful detail.
I would suggest like for getting a general information massively use Process Explorer.
One time you gfigure out you need to understand the stuff deeper (what kind of objects are on heap, for example) , the best tool I used for profiling is JetBrains Memory and Performance profiler. This one is payed only.
If you need only performance profiler, there is really good free option Equatec Performance profiler
Good luck.
I am using C# 2.0 for a multi-threaded application that receives atleast thousand callbacks per second from an unmanaged dll and periodically send messages out of socket. GUI remains on main thread.
My application mostly creates object at the startup and periodically during the execution for a short lived period.
The problem I am experiencing is periodic latency spike (measured by time stamping a function at start and end) which I suppose happen when GC run.
I ran perfmon and here are my observations...
Gen0 Heap Size is flat with a spike every few seconds with periodic spike.
Gen1 Heap Size is always on the roll. Up and down
Gen2 Heap Size follows a cycle. It keep increasing till it becomes flat for a while and then drops.
Gen 0 and 1 Collections are always increasing in a range of 1 to 5 units.
Gen 2 collections is constant.
I recommend using a memory profiler in order to know if you have a real memory leak or not. There are many available and they will allow you to quickly isolate any issue.
The garbage collector is adaptive and will modify how often it runs in response to the way your application is using memory. Just looking at the generation heap sizes is going to tell you very little in terms of isolating the source of any problem. Second quessing how it works is a bad idea.
RedGate Ants Memory Profiler
SciTech .NET Memory Profiler
EQATEC .NET Profiler
CLR Profiler (Free)
So as #Jalf says, there's no evidence of a memory "leak" as such: what you discuss is closer to latency caused by garbage collection.
Others may disagree but I'd suggest anything above a few hundred callbacks per second is going to stretch a general purpose language like C#, especially one that manages memory on your behalf. So you're going to have to get smart with your memory allocation and give the runtime some help.
First, get a real profiler. Perfmon has its uses but even the profiler in later versions of Visual Studio can give you much more information. I like the SciTech profiler best (http://memprofiler.com/); there are others including a well respected one from RedGate reviewed here: http://devlicio.us/blogs/scott_seely/archive/2009/08/23/review-of-ants-memory-profiler.aspx
Once you know your baseline, aim to eliminate gen2 collections. They'll be the really slow ones. Work hard in any tight loops to eliminate as much memory allocation as you can -- strings are the usual offenders.
Some useful tips are in an old but still relevant MSDN article here: http://msdn.microsoft.com/en-us/library/ms973837.aspx.
It's also good to read Tess Ferrandez's (outstanding) blog series on debugging ASP.NET applications - book a day out of the office and start here: http://blogs.msdn.com/b/tess/archive/2008/02/04/net-debugging-demos-information-and-setup-instructions.aspx.
I remember reading a blog post about memory performance in .NET (specifically, XNA on the XBox 360) a while ago (unfortunately I can't find said link anymore).
The nutshell of achieving low latency memory performance was to make sure you never run gen 2 GC's at a performance critical time (although it is OK to run them when latency is not important; there are a bunch of notification callback functions on the GC class in more recent versions of the framework which may help with this). There are two ways to make sure this happens:
Don't allocate anything that escapes to gen 2. It's alarmingly easy for objects to escape to gen 2 when you don't realise it, so this often translates into: don't allocate anything in performance critical code. Because no objects escape to gen 2, the GC doesn't need to collect.
Allocate everything you need upfront and use object pooling. Your gen 2 heap will be big but because nothing is being added to it, the GC doesn't need to collect it.
It may be helpful to look into some XNA or Silverlight related performance articles because
games and resource constrained devices are often very latency sensitive. (Note that you have it easy because the XBox 360 and, until Mango, Windows Phone only had a single generation GC (mark-and-sweep collector)).
How I can get the actual memory used in my C# application?
Task Manager shows different metrics.
Process Explorer shows increased usage of private bytes.
Performance counter (perfmon.msc) showed different metrics
when I used .NET memory profiler, it showed most of the memory is garbage collected and only few Live bytes.
I do not know which to believe.
Memory usage is somewhat more complicated than displaying a single number or two. I suggest you take a look at Mark Russinovich's excellent post on the different kinds of counters in Windows.
.NET only complicates matters further. A .NET process is just another Windows process, so obviously it will have all the regular metrics, but in addition to that the CLR acts as a memory manager for the managed application. So depending on the point of view these numbers will vary.
The CLR effectively allocates and frees virtual memory in big chunks on behalf of the .NET application and then hands out bits of memory to the application as needed. So while your application may use very little memory at a given point in time this memory may or may not have been released to the OS.
On top of that the CLR itself uses memory to load IL, compile IL to native code, store all the type information and so forth. All of this adds to the memory footprint of the process.
If you want to know how much memory your managed application uses for data, the Bytes in all heaps counter is useful. Private bytes may be used as a somewhat rough estimate for the application's memory usage on the process level.
You may also want to check out these related questions:
Reducing memory usage of .NET applications?
How to detect where a Memory Leak is?
If you are using VS 2010 you can use Visual Studio 2010 Profiler.
This tool can create very informative reports for you.
If you want to know approximately how many bytes are allocated on the GC heap (ignoring memory used by the runtime, the JIT compiler, etc.), you can call GC.GetTotalMemory. We've used this when tracking down memory leaks.
Download VADump (If you do not have it yet)
Usage: VADUMP.EXE -sop [PID]
Well, what is "actual memory used in my C# application" ?
Thanks to Virtual memory and (several) Memory management layers in Windows and the CLR, this is a rather complicated question.
From the sources you mention the CLR profiler will give you the most detailed breakdown, I would call that the most accurate.
But there is no 'single number' answer, the question whether Application A use more or less memory than B can be impossible to answer.
So what do you actually want to know? Do you have a concrete performance problem to solve?
Are there any good, free tools to profile memory usage in C# ?
Details:
I have a visualization project that uses quite large collections. I would like to check which parts of this project - on the data-processing side, or on the visualization side - use most of the memory, so I could optimize it.
I know that when it comes to computing size of the collection the case is quite simple and I can do it on my own. But there are also certain elements for which I cannot estimate the memory usage so easily.
The memory usage is quite big, for example processing a file of size 35 MB my program uses a little bit more than 250 MB of RAM.
I've had success using RedGate's ANTS profiler. It is also worth reading Brad Abrams blog where he has talked about profiling memory
I'm amazed noone has mentioned the free CLR Profiler from Microsoft!
I didn't know of this tool until recently. I had a bug that made my program keep allocating more and more memory. The CLR Profiler can pinpoint memory-allocating "hot spots" in your program.
I identified the line of code responsible for the leak, within 15-20 minutes of installing the profiler.
Basically, it instruments your code and runs it with some profiling (which slows down your code considerably, 10x-100x are the official figures I think).
You run a certain workload for a certain amount of time, and you can then see which places in your code that allocated how much memory (and how much was freed versus how much was retained etc.).
Check it out at: https://clrprofiler.codeplex.com/
Also, here is a tutorial on how to use the tool: http://geekswithblogs.net/robp/archive/2009/03/13/speedy-c-part-4-using---and-understanding---clr.aspx
JetBrains DotTrace is also good. I have used both the RedGate and JetBrains products and they both do a very good job of identifying the bottlenecks and leaks.