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C# Memory Issues

I've got an application that:
Targets C# 6
Targets .net 4.5.2
Is a Windows Forms application
Builds in AnyCPU Mode beacuse it...
Utilizes old 32 bit libraries that cannot be upgraded to 64 bit, unmanaged memory
Uses DevExpress, a third party control vendor
Processes many gigabytes of data daily to produce reports
After a few hours of use in jobs that have many plots, the application eventually runs out of memory. I've spend quite a long time cleaning up many leaks found in the code and have gotten the project to a state where at the worst case it may be using upwards 400,000K of memory at any given time, according to performance counters. Processing this data has not yielded any issues at this point since data is processed in Jagged arrays, preventing any issues with the Large Object Heap.
Last time this happened the user was using ~305,000K of memory. The application is so "out of memory" that the error dialog cannot even draw the error icon in the MessageBox that comes up, the space where the icon would usually be is all black.
So far I've done the following to clean this up:
Windows forms utilize the Disposed event to ensure that resources are cleaned up, dispose is called manually when required
Business objects utilize IDisposable to remove references
Verified cleanup using ANTS memory profiler and SciTech memory profiler.
The low memory usage suggests this is not the case but I wanted to see if I saw anything that could be helpful, I could not
Utilized the GCSettings.LargeObjectHeapCompactionMode property to remove any fragmentation from processing data that may be fragmented in the Large Object Heap (LoH)
Nearly every article that I've used to get to this point suggests that out of memory actually means out of contiguous address space and given the amount that's in use, I agree with this. I'm not sure what to do at this point since from what I understand (and am probably very wrong about) is that the garbage collector clears this up to make room as the process moves along, with the exception of the LoH, which is cleaned up manually now using the new LargeObejctHeapCompactionMode property introduced in .net 4.5.1.
What am I missing here? I cannot build to 64 bit due to the old 32 bit libraries that contain proprietary algorithms that we do not have access to even dream of producing a 64 bit version of. Are there any modes in these profiles I should be using to identify exactly what is growing out of control here?
If this address space cannot be cleared up does this mean that all c# applications will eventually run "out of memory" because of this?

Nearly every article that I've used to get to this point suggests that out of memory actually means out of contiguous address space and given the amount that's in use, I agree with this.
This is a reasonable hypothesis, but even reasonable hypotheses can be wrong. Yours probably is wrong. What should you do?
Test it with science. That is, look for evidence that falsifies your hypothesis. You want to assume that it is anything else, and be forced by the evidence you've gathered that your hypothesis is not false.
So:
at the point where your application runs out of memory, is it actually out of contiguous free pages of the necessary size? It sure sounds like your observations do not indicate that this is true, so the hypothesis is probably false.
What is other evidence that the hypothesis might be false?
"After a few hours of use in jobs that have many plots, the application eventually runs out of memory."
"Uses DevExpress, a third party control vendor"
"the error dialog cannot even draw the error icon in the MessageBox"
None of this sounds like an out of memory problem. This sounds like a third party control library leaking OS handles for graphics objects. Unfortunately, such leaks usually surface as "out of memory" errors and not "out of handles" errors.
So, that's a new hypothesis. Look for evidence for and against this hypothesis too. You're doing a good job by using a memory profiler. Use a handle profiler next.
If this address space cannot be cleared up does this mean that all c# applications will eventually run "out of memory" because of this?
Nope. The GC does a good job of cleaning up managed memory; lots of applications have no problem running forever without leaking.

Tracking Down a .NET Windows Service Memory Leak

Before installing my windows service in production, I was looking for reliable tests that I can perform to make sure my code doesn't contain memory leaks.
However, All what I can find on the net was using task manager to look at used memory or some paid memory profiler tools.
From my understanding, looking at the task manager is not really helpful and cannot confirm the memory leakage (in case, there is).
How to confirm whether there is a memory leak or not?
Is there any free tools to find the source of memory leaks?
Note: I'm using .Net Framework 4.6 and Visual Studio 2015 Community

Well you can use task manager.
GC apps can leak memory, and it will show there.
But...
Free tool - ".Net CLR profiler"
There is a free tool, and it's from Microsoft, and it's awesome. This is a must-use for all programs that leak references. Search MS' site.
Leaking references means you forget to set object references to null, or they never leave scope, and this is almost as likely to occur in Garbage collected languages as not - lists building up and not clearing, event handlers pointing to delegates, etc.
It's the GC equivalent of memory leaks and has the same result. This program tells you what references are taking up tons of memory - and you will know if it's supposed to be that way or not, and if not, you can go find them and fix the problem!
It even has a cool visualization of what objects allocate what memory (so you can track down mistakes). I believe there are youtubes of this if you need an explanation.
Wikipedia page with download links...
NOTE: You will likely have to run your app not as a service to use this. It starts first and then runs your app. You can do this with TopShelf or by just putting the guts in a dll that runs from an EXE that implments the service integrations (service host pattern).

Although managed code implies no direct memory management, you still have to manage your instances. Those instances 'claim' memory. And it is all about the usage of these instances, keeping them alive when you don't expect them to be.
Just one of many examples: wrong usage of disposable classes can result in a lot of instances claiming memory. For a windows service, a slow but steady increase of instances can eventually result in to much memory usage.
Yes, there is a tool to analyze memory leaks. It just isn't free. However you might be able to identify your problem within the 7 day trial.
I would suggest to take a loot at the .NET Memory Profiler.
It is great to analyze memory leaks during development. It uses the concept of snapshots to compare new instances, disposed instances etc. This is a great help to understand how your service uses its memory. You can then dig deeper into why new instances get created or are kept alive.
Yes, you can test to confirm whether memory leaks are introduced.
However, just out-of-the box this will not be very useful. This is because no one can anticipate what will happen during runtime. The tool can analyze your app for common issues, but this is not guaranteed.
However, you can use this tool to integrate memory consumption into your unit test framework like NUnit or MSTest.

Of course a memory profiler is the first kind of tool to try, but it will only tell you whether your instances keep increasing. You still want to know whether it is normal that they are increasing. Also, once you have established that some instances keep increasing for no good reason, (meaning, you have a leak,) you will want to know precisely which call trees lead to their allocation, so that you can troubleshoot the code that allocates them and fix it so that it does eventually release them.
Here is some of the knowledge I have collected over the years in dealing with such issues:
Test your service as a regular executable as much as possible. Trying to test the service as an actual service just makes things too complicated.
Get in the habit of explicitly undoing everything that you do at the end of the scope of that thing which you are doing. For example, if you register an observer to the event of some observee, there should should always be some point in time (the disposal of the observer or the observee?) that you de-register it. In theory, garbage collection should take care of that by collecting the entire graph of interconnected observers and observees, but in practice, if you don't kick the habit of forgetting to undo things that you do, you get memory leaks.
Use IDisposable as much as possible, and make your destructors report if someone forgot to invoke Dispose(). More about this method here: Mandatory disposal vs. the "Dispose-disposing" abomination Disclosure: I am the author of that article.
Have regular checkpoints in your program where you release everything that should be releasable (as if the program is performing an orderly shutdown in order to terminate) and then force a garbage collection to see whether you have any leaks.
If instances of some class appear to be leaking, use the following trick to discover the precise calling tree that caused their allocation: within the constructor of that class, allocate an exception object without throwing it, obtain the stack trace of the exception, and store it. If you discover later that this object has been leaked, you have the necessary stack trace. Just don't do this with too many objects, because allocating an exception and obtaining the stack trace from it is ridiculously slow, only Microsoft knows why.

You could try the free Memoscope memory profiler
https://github.com/fremag/MemoScope.Net
I do not agree that you can trust the Task Manager to check if you have a memory leak or not. The problem with a garbage collector is that it can decide based on heuristics to keep the memory after a memory spike and do not return it to the OS. You might have a 2 GB Commit size but 90% of them can be free.
You should use VMMAP to check during the tests what type of memory your process contains. You do not only have the managed heap, but also unmanaged heap, private bytes, stacks (thread leaks), shared files and much more which need to be tracked.
VMMap has also command line interface which makes it possible to create snapshots at regular intervals which you can examine later. If you have a memory growth you can find out which type of memory is leaked which needs depending on the leak type different debugging tooling approaches.

I would not say that the Garbage collector is infallible. There are times when it fails unknowingly and they are not so straight forward. Memory streams are a common cause of memory leaks. You can open them in one context and they may never even get closed, even though the usage is wrapped in a using statement (the definition of a disposable object that should be cleaned up immediately after its usage falls out of scope). If you are experiencing crashes due to running out of memory, Windows does create dump files that you can sift through.
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This is by no means fun or easy and is quite tedious but it tends to be your best bet.
Common areas that are easy to create memory leaks are anything that is using the System.Drawing dll, memory streams, and if you are doing some serious multi-threading.

If you use Entity Framework and a DI pattern, perhaps using Castle Windsor, you can easily get memory leaks.
The main thing to do is use the using( ){ } statement where-ever you can to automatically mark objects as disposed.
Also, you want to turn off automatic tracking on Entity Framework where you are only reading and not writing. Best to isolate your writes, use a using() {} at this point, get a dbContext (with tracking on), write your data.
If you want to investigate what is on the heap. The best tool I've used is RedGate ANTS http://www.red-gate.com/products/dotnet-development/ants-memory-profiler/solving-memory-problems/getting-started not cheap but it works.
However, by using the using() {} pattern where-ever you can (don't make a static or singleton DbContext and never have one context in a massive loop of updates, dispose of them as often as you can!) then you find memory isn't often an issue.
Hope this helps.

Unless you're dealing with unmanaged code, i would be so bold to say you don't have to worry about memory leaks. Any unreferenced object in managed code will be removed by the garbage collector, and the possibility in finding a memory leak within the .net framework i would say you should be considered very lucky (well, unlucky). You don't have to worry about memory leak.
However, you can still encounter ever-growing memory usage, if references to objects are never released. For example, say you keep an internal log structure, and you just keep adding entries to a log list. Then every entry still have references from the log list and therefore will never be collected.
From my experience, you can definitely use the task manager as an indicator whether your system has growing issues; if the memory usage steadily keep rising, you know you have an issue. If it grows to a point but eventually converges to a certain size, it indicates it has reached its operating threshold.
If you want a more detailed view of managed memory usage, you can download the process explorer here, developed by Microsoft. It is still quite blunt, but it gives a somewhat better statistical view than task manager.

UWP application is getting slow after usage of some time?

I have developed one UWP application.In that nearly 20 windows are there.
Every window contains lot of Xaml controls. For some time it's working fine.
But after usage of some time application is getting very slow.
After doing some R&D I came to know that it's called Memory Leakage.
As per my knowledge in .Net Garbage Collector has to take care of this if I am not wrong.It seems like In UWP Application it is not happening. So I thought I should use GC.Collect() in Page Unload Event.
Is that correct approach or anything else I need to do to release memory which are used by the window controls?

The performance optimization is a vast subject and may not be possible to answer on an open ended question (without knowledge of your environment and architecture etc).
However you can use the Visual Studio profiler to measure and track performance and to find out the area where you need to take action, these can be;
Data binding
UI Virtualization
Image rendering
Visual Tree Size
Further reading these urls may also help you.
ms docs and this blog

The GC takes care of orphaned objects or objects that are no longer referenced by any other classes. when the GC finds objects like these it removes them from memory. memory leaks happen when an object is referenced by another class even after it is done with it. this means you need to look at your code and find where this is happening. you need to help GC in doing its job by making sure you no longer reference objects you don't need.
I also wouldn't recommend using GC.Collect in page unload event since GC has to freeze threads in order to collect. this might impact performance.

System.OutOfMemory being thrown. How to find the culprit?

I am using Visual C# Express 2008 and I have an application that starts up on a form, but uses a thread with a delegated display function to take care of essentially all the processing. That way my form doesn't lock up while tasks are being processed.
Semi-recently, after going through a repeated process a number of times (the program processes incoming data, so when data comes in, the process repeats) my app will crash with a System.OutOfMemory error.
The stack trace in the error message is useless because it only directs me to the the line where I call the delegated form control function.
I've heard people say they use ProcMon from SysInternals to see why errors like this happen. But I, for the life of me, can't figure it out. The amount of memory I am using doesn't change as the program runs, if it goes up, it comes back down. Plus, even if it was going up, how do I figure out which part of my program is the problem?
How can I go about investigating this problem?
EDIT:
So, after delving further into this issue, I looked through anything that I was ever re-declaring. There were a few instances where I had hugematrix = new uint[gigantic], so I got rid of about 3 of those.
Instead of getting rid of the error, it is now far more obscured and confusing.
My application takes the incoming data, and renders it using OpenGL. Now, instead of throwing "System.OutOfMemory" it simply does not render anything with OpenGL.
The only difference in my code is that I do not make new matrices for holding the data I plot. That way, I hope, my array stays in the same place in memory and doesn't do anything suicidal to my LOH.
Unfortunately, this twists the beast far beyond my meager means. With zero errors popping up, and all my data structures apparently still properly filled, how can I find my problem? Does OpenGL use memory in an obscure way so as to not throw exceptions when it fails? Is memory still a problem? How do I find out? All the memory profilers in the world seem to tell me very little.
EDIT:
With the boatloads of support from this community (with extra kudos to Amissico) the error has finally been rooted out. Apparently I was adding items to an OpenGL list, and never taking them off the list.
The app that finally clued me in was .Net Memory Profiler. At the time of crash it showed 1.5GB of data in the <unknown> category. Through process of elimination (everything else in the list that was named), the last thing to be checked off the list was the OpenGL rendering pipleline. The rest is history.

Based on the description in your comments, I would suspect that you are either not disposing of your images correctly or that you have severe Large Object Heap fragmentation and, when trying to allocate for a new image, don't have enough contiguous space available. See this question for more info - Large Object Heap Fragmentation

You need to use a memory profiler, such as the ants memory profiler to find out what causes this error.
Are you re-registering an event handler on every loop and not un-registering it?

CLR Profiler for the .NET Framework 2.0 at https://github.com/MicrosoftArchive/clrprofiler
The most common cause of memory fragmentation is excessive string creation.

Following considerations:
Make sure that threads you spawn are destroyed (aborted or function return). Too much threads can fail application, although in Task Manager used memory is not too high
Memory leaks. Yes, yes, you can cause them in .net pretty well without setting reference to nulls. This can be solved by using memory profilers like dotTrace or ANTS Memory Profiler

I had an OutOfMemoryException-problem as well:
Microsoft Visual C# 2008 Reducing number of loaded dlls
The reason was fragmentation of 2GB GB virtual address space and poster nobugz suggested Sysinternal's Vmmap utility which has been very helpful for diagnostics. You can use it to check if your free memory areas become more fragmented over time. (First sort by size then by type -> refresh repeat sorting and you can see if contiguous free memory blocks become smaller)

What strategies and tools are useful for finding memory leaks in .NET?

I wrote C++ for 10 years. I encountered memory problems, but they could be fixed with a reasonable amount of effort.
For the last couple of years I've been writing C#. I find I still get lots of memory problems. They're difficult to diagnose and fix due to the non-determinancy, and because the C# philosophy is that you shouldn't have to worry about such things when you very definitely do.
One particular problem I find is that I have to explicitly dispose and cleanup everything in code. If I don't, then the memory profilers don't really help because there is so much chaff floating about you can't find a leak within all the data they're trying to show you. I wonder if I've got the wrong idea, or if the tool I've got isn't the best.
What kind of strategies and tools are useful for tackling memory leaks in .NET?

I use Scitech's MemProfiler when I suspect a memory leak.
So far, I have found it to be very reliable and powerful. It has saved my bacon on at least one occasion.
The GC works very well in .NET IMO, but just like any other language or platform, if you write bad code, bad things happen.

Just for the forgetting-to-dispose problem, try the solution described in this blog post. Here's the essence:
public void Dispose ()
{
// Dispose logic here ...
// It's a bad error if someone forgets to call Dispose,
// so in Debug builds, we put a finalizer in to detect
// the error. If Dispose is called, we suppress the
// finalizer.
#if DEBUG
GC.SuppressFinalize(this);
#endif
}
#if DEBUG
~TimedLock()
{
// If this finalizer runs, someone somewhere failed to
// call Dispose, which means we've failed to leave
// a monitor!
System.Diagnostics.Debug.Fail("Undisposed lock");
}
#endif

We've used Ants Profiler Pro by Red Gate software in our project. It works really well for all .NET language-based applications.
We found that the .NET Garbage Collector is very "safe" in its cleaning up of in-memory objects (as it should be). It would keep objects around just because we might be using it sometime in the future. This meant we needed to be more careful about the number of objects that we inflated in memory. In the end, we converted all of our data objects over to an "inflate on-demand" (just before a field is requested) in order to reduce memory overhead and increase performance.
EDIT: Here's a further explanation of what I mean by "inflate on demand." In our object model of our database we use Properties of a parent object to expose the child object(s). For example if we had some record that referenced some other "detail" or "lookup" record on a one-to-one basis we would structure it like this:
class ParentObject
Private mRelatedObject as New CRelatedObject
public Readonly property RelatedObject() as CRelatedObject
get
mRelatedObject.getWithID(RelatedObjectID)
return mRelatedObject
end get
end property
End class
We found that the above system created some real memory and performance problems when there were a lot of records in memory. So we switched over to a system where objects were inflated only when they were requested, and database calls were done only when necessary:
class ParentObject
Private mRelatedObject as CRelatedObject
Public ReadOnly Property RelatedObject() as CRelatedObject
Get
If mRelatedObject is Nothing
mRelatedObject = New CRelatedObject
End If
If mRelatedObject.isEmptyObject
mRelatedObject.getWithID(RelatedObjectID)
End If
return mRelatedObject
end get
end Property
end class
This turned out to be much more efficient because objects were kept out of memory until they were needed (the Get method was accessed). It provided a very large performance boost in limiting database hits and a huge gain on memory space.

You still need to worry about memory when you are writing managed code unless your application is trivial. I will suggest two things: first, read CLR via C# because it will help you understand memory management in .NET. Second, learn to use a tool like CLRProfiler (Microsoft). This can give you an idea of what is causing your memory leak (e.g. you can take a look at your large object heap fragmentation)

Are you using unmanaged code? If you are not using unmanaged code, according to Microsoft, memory leaks in the traditional sense are not possible.
Memory used by an application may not be released however, so an application's memory allocation may grow throughout the life of the application.
From How to identify memory leaks in the common language runtime at Microsoft.com
A memory leak can occur in a .NET
Framework application when you use
unmanaged code as part of the
application. This unmanaged code can
leak memory, and the .NET Framework
runtime cannot address that problem.
Additionally, a project may only
appear to have a memory leak. This
condition can occur if many large
objects (such as DataTable objects)
are declared and then added to a
collection (such as a DataSet). The
resources that these objects own may
never be released, and the resources
are left alive for the whole run of
the program. This appears to be a
leak, but actually it is just a
symptom of the way that memory is
being allocated in the program.
For dealing with this type of issue, you can implement IDisposable. If you want to see some of the strategies for dealing with memory management, I would suggest searching for IDisposable, XNA, memory management as game developers need to have more predictable garbage collection and so must force the GC to do its thing.
One common mistake is to not remove event handlers that subscribe to an object. An event handler subscription will prevent an object from being recycled. Also, take a look at the using statement which allows you to create a limited scope for a resource's lifetime.

This blog has some really wonderful walkthroughs using windbg and other tools to track down memory leaks of all types. Excellent reading to develop your skills.

I just had a memory leak in a windows service, that I fixed.
First, I tried MemProfiler. I found it really hard to use and not at all user friendly.
Then, I used JustTrace which is easier to use and gives you more details about the objects that are not disposed correctly.
It allowed me to solve the memory leak really easily.

If the leaks you are observing are due to a runaway cache implementation, this is a scenario where you might want to consider the use of WeakReference. This could help to ensure that memory is released when necessary.
However, IMHO it would be better to consider a bespoke solution - only you really know how long you need to keep the objects around, so designing appropriate housekeeping code for your situation is usually the best approach.

I prefer dotmemory from Jetbrains

Big guns - Debugging Tools for Windows
This is an amazing collection of tools. You can analyze both managed and unmanaged heaps with it and you can do it offline. This was very handy for debugging one of our ASP.NET applications that kept recycling due to memory overuse. I only had to create a full memory dump of living process running on production server, all analysis was done offline in WinDbg. (It turned out some developer was overusing in-memory Session storage.)
"If broken it is..." blog has very useful articles on the subject.

After one of my fixes for managed application I had the same thing, like how to verify that my application will not have the same memory leak after my next change, so I've wrote something like Object Release Verification framework, please take a look on the NuGet package ObjectReleaseVerification. You can find a sample here https://github.com/outcoldman/OutcoldSolutions-ObjectReleaseVerification-Sample, and information about this sample http://outcoldman.com/en/blog/show/322

The best thing to keep in mind is to keep track of the references to your objects. It is very easy to end up with hanging references to objects that you don't care about anymore.
If you are not going to use something anymore, get rid of it.
Get used to using a cache provider with sliding expirations, so that if something isn't referenced for a desired time window it is dereferenced and cleaned up. But if it is being accessed a lot it will say in memory.

One of the best tools is using the Debugging Tools for Windows, and taking a memory dump of the process using adplus, then use windbg and the sos plugin to analyze the process memory, threads, and call stacks.
You can use this method for identifying problems on servers too, after installing the tools, share the directory, then connect to the share from the server using (net use) and either take a crash or hang dump of the process.
Then analyze offline.

From Visual Studio 2015 consider to use out of the box Memory Usage diagnostic tool to collect and analyze memory usage data.
The Memory Usage tool lets you take one or more snapshots of the managed and native memory heap to help understand the memory usage impact of object types.

one of the best tools I used its DotMemory.you can use this tool as an extension in VS.after run your app you can analyze every part of memory(by Object, NameSpace, etc) that your app use and take some snapshot of that, Compare it with other SnapShots.
DotMemory