Why is my application pool having memory usage spikes? - asp.net

I hosted my application in production. Within 5 to 6 hours the application pool spikes and uses more memory?
What application objects or system objects are stored in the application pool?

An application pool is a worker process spawned by IIS to host one or more applications. The memory raise behavior you are observing could be due to various reasons such as objects that hold unmanaged resources not being disposed properly, storing large objects in the application state, ... You could use a profiler to find the exact cause.

If you are looking for memory leaks, try downloading the trial version of MemProfiler (or one of the other products available).

In addition to the answers by Mitch and Darin, I'd also recommend taking a look at Tess Ferrandez's excellent blog which deals with issues such as memory/use leaks:
.NET Debugging Demos Lab 3: Memory
.NET Debugging Demos Lab 6: Memory Leak
.NET Debugging Demos Lab 7: Memory Leak

Related

MVC 4 website memory leak detecting

i have a MVC4 website. When i running it on the Hosting i got very high memory
Process Info {2 processes)
PID/Name: 96148 - w3wp
Start/Uptime: 12/15/2014 8:41:53 AM - 00:01:26
CPU Time: 00:02:18
Working set (memory): 1.41 GB
How can i figure out the problem? I do not have experience with memory leak. My website is working well on Local. I think because online site have many users access (i have around 1.5m page views per month).
There are too many possibilities. Normally, if your application cache a lot in SessionState or Runtime.Caching, it'll eventually run out of memory.
Without seeing your application, we cannot tell what causes the issue. The first thing I'll do is to profile with Memory Profiler.
For example -
Red-Gate - ANTS Memory Profiler
JetBrain - dotTrace
Telerik - JustTrace

debug memory usage

One of our ASP.NET MVC3 web app takes too much memory while hosted on single IIS7 pool. Sometimes up to 1gb. Where I should start and how to find memory issues, any suggestions?
I would look at the database first, as that will be mostly the case to step up your memory allocation.
Are you closing all open connections?
Are you reusing the open connection to get more data from the database?
Are you open and close the connection for each call?
There are several tools out there that provide you with Profiling, both code and memory, but before jumping out into one of them, try "our" own StackOverflow Profiling now called Mini Profiler to help you realize where are you wasting more time, how long your queries take and see if you're doing the database access correctly...
If that does not help, try one of the free/commercial tools out there like:
.Net Memory Profiler
ANTS Performance Profiler
dotTrace 4 Performance
EQATEC Profiler
or follow up this question
Any decent C# profilers out there?

High memory usage with w3wp application pool IIS 7

I have a website application running in it's own application pool on IIS 7.0. The application is an ASP.NET MVC 3 website.
I have noticed the memory usage for this applications corresponding w3wp IIS worker service is quite high ( 800 MB, with some fluctuation ).
I am trying to diagnose the problem and have tried the following:
I have disabled output page caching for the website at IIS level and then recycled the application pool. This causes the w3wp process to restart. The memory usage for this process then slowly creeps up to around 800 MB, it takes around 30 seconds to do so. There are no page requests being handled at this time. When I restart the website from IIS the memory size of the process does not alter.
I have tried running a debug copy of the application from VS 2010, there are no problems with memory usage.
Some ideas I have/questions are:
Is this problem related to the websites code? - Given that the memory rockets before any page requests have been sent/handled, I would assume this is NOT a code problem?
The application built in MVC has no handling of caching written into it.
The website uses real-time displaying of data, it uses ajax requests periodically, and is generally left 'open' for long periods of time.
Why does the memory usage rocket up after the application is recycled and no user requests are being sent? Is this because it is loading old cache information into it's memory from disk?
The application does NOT crash, I'm just concerned about the memory usage, it is not that big of a website...
Any ideas/help with getting to the bottom of this problem would be appreciated.
The best thing to do if you can afford to use a debugger is install the Windows Debugging Tools and use something like WinDbg and SOS.dll to figure out exactly what is it in memory.
once you've installed the tools then you can:
Launch Windbg.exe running elevated (as Administrator)
Use "File->Attach To Process" and choose w3wp.exe for the app you are trying to figure out. If you have many you can use Task Manager and add the command-line column to see the PID or use IIS Manager->Worker Processes to figure it out, and then choose that process in WinDBG.
run:
.loadby sos clr
!dumpheap -stat
At that point you should be able to see all types sorted by the most memory consumption so you can start with the ones at the bottom. (I would recommend exclude Strings, and Object since those are usually a side-effect and not the cause).
Use "!dumpheap -type type-here" to find the instances and use !gcroot for those to figure out why they are in memory, maybe due to a static field, or an event handler leaked, WCF channels not disposed, or things like that are common sources.
I just looked my server and my pools use 900-1000 MB Virtual size Memory, and 380 MB Working set. My sites run smooth with out problem for some years now, and I have checked the sites from all sides. My pool never recycles and the server runs until the next update continuously with 40% stable free physical memory.
If your memory is not continuously growing, then this memory is the code plus the data that you set as static, const, the string, and the possible cache, inside your application.
You can use process explorer to see the working and the virtual size memory.
You can also think to run a profile against your code to see if you have any "memory leak" or other issue. Find one from google: https://www.google.com/search?hl=en&q=asp.net+memory+profiler.
It probably doesn't apply here but thought I would throw it in for good measure. Recently I had a problem where my memory would go right up and max out when it really could of cleaned up 80% of it. Problem: It thought it about 2 more gig than it actually did so the GC was quite lazy. (It was due to a VM ware bug -windows was reporting 8 Gig but physically there was only 6.4). See blog.http://www.worthalook.net/2014/01/give-back-memory/
Something that might help: if you "rewrite" (open/save) the web.config , then your application will reset, you should monitor the memory usage from that point. If it keeps growing during usage, this could mean memory leak or insane caching. You might be able to identify which actions on your site lead to memory increase. During a long time the memory usage of an application should be stable.

Asp.net Application throwing System.OutOfMemoryException in Windows server 2003

I am using Neo load to test the performance of my ASP.NET 2.0 application. The application works fine until the memory of the w3wp.exe process reaches about 800000K and then it starts throwing System.OutOfMemoryException. The ASP.NET application is hosted in Windows server 2003 SP2 machine and the machine has 4GB of RAM. How can i get to know the reason for this error.
The 800000K threshold is also mentioned (as 800MB) in the following article:
Troubleshooting System.OutOfMemoryExceptions in ASP.NET
When your worker process approaches 800MB in private bytes, your
chances of seeing an OOM condition begin to increase simply because
the chances of finding a large, contiguous piece of memory within the
2GB address space begin to decrease significantly.
The article then goes on to cover common scenarios that lead to this situation, such as the usage of large data sets, runaway session or application data storage, usage of debuggable assemblies, lots of exceptions thrown and even certain uses of regular expressions.
It ends with some pointers to resources to help troubleshooting Out of Memory exceptions, like the Debug Diagnostic Tool and information about garbage collection in .NET. But the most valuable resource may be this list of 21 blog posts from an ' escalation engineer' at Microsoft's ASP.NET developer support team:
MSDN Blogs > If broken it is, fix it you should > The 21 most popular blog posts

How to measure memory usage for a Live ASP.NET MVC web application?

So right off the bat, not sure if this question is better suited for another StackExchange site.
I've got an ASP.NET MVC 3 web application running on Windows Server 2008 and IIS 7.5
Site runs fine initially, but i can see the memory usage gradually growing. After about 12 hours it's nearly out of memory and the site chokes.
I'm using a lot of caching, so i'm thinking this combined with some possibly memory leaks is the cause of the issue.
So my question - what's the best way (tools, for example) to monitor memory usage on a web server running ASP.NET MVC?
In the past i've used good old' perfmon and put the IIS counters on to measure these things.
It this still the best way, and if so, can someone recommend a good perfmon counter template for my scenario?
Perfmon's counters are still a good technique (and free!).
PAL (Performance Analysis of Logs), a free tool, has an ASP.NET perfmon counter template for general health (in addition to generating reports of counter log files based on thresholds).
Check out:
.NET Debugging Demos Lab 7: Memory Leak
.NET Memory Leak Case Study: The Event Handlers That Made The Memory Baloon
Tracking down managed memory leaks (how to find a GC leak)
Determine if your .NET Application has a Memory Leak
Commercial tools like MemProfiler, RedGate's memory profiling tool and JetBrains Profiler are all very good (and all have free trials).

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