I have recently installed NewRelic server monitoring to our Azure web role. The role is a small instance. We are on OSv4 (Win 2012 R2) using 2.2 Service Runtime.
Looking at memory usage I notice that WallSHost.exe (which I understand to be Azure related) it reported as consuming 219Mb (down from a peak of 250Mb) via NewRelic. Is that a lot of memory for it? Can I reduce it? Just seemed like a lot to be taking up.
CPU usage seems to aperiodically spike at about 4% for it. However CPU isn't really an issue as my instance rarely goes above 50%
First off, why do you care how much memory a process is taking up? All of that memory will be paged out to disk, and assuming it isn't being paged back in regularly then all it does is take up page file size which is usually irrelevant.
The WaIISHost process runs your role entry point code (OnStart, Run, StatusCheck, Changing, etc) and is typically implemented in WebRole.cs. If you want to reduce the memory size of this process then you can reduce the amount of memory being loaded by your role entry point code.
See http://blogs.msdn.com/b/kwill/archive/2011/05/05/windows-azure-role-architecture.aspx for more information about the WaIISHost.exe process and what it does.
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I have multiple micro-services written in Node and running on pm2. Whenever there is a high traffic on any of these micro-services, the memory doesn't exceed 800 MB even though the system has more than 10GB of memory free. Instead the system becomes slow. I have used only the below command with no additional settings to start the services.
pm2 start app.js --name='app_name'
I have gone through the docs for pm2 but it only mention about limiting the memory usage using max-memory-restart. Is there a way I can make sure my micro-services use all the available system memory.
Whenever there is a high traffic on any of these micro-services, the memory doesn't exceed 800 MB even though the system has more than 10GB of memory free. Instead the system becomes slow.
You need to look at CPU metrics too, not just memory. More likely than not, those services aren't starved for memory and would begin to swap out to disk, but are just working your server's CPUs.
Profiling your services wouldn't hurt either, to find any possible bottlenecks or stalls that occur during high load.
Is there a way I can make sure my micro-services use all the available system memory.
Yes, there is: use more memory in those services. There's no intrinsic limit unless you've configured one.
I've got an app service plan with 14gb of memory - it should be plenty for my application's needs. There are two application services running on it, each identical - the private memory consumption of these hovers around 1gb but can spike to 4gb during periods of high usage. One app has a heavier usage pattern than the other.
Lately, during periods of high usage, I've noticed that the heavily used service can become unresponsive, and memory usage stays at 100% in the App Service Plan.
The high traffic service is using 4gb of private memory and starting to massively slow down. When I head over to the /scm.../ProcessExplorer/ page, I can see that the low traffic service has 1gb private memory used and 10gb of 'Working Set'.
As I understand it, on a single machine at least, the working set should be freed up when that memory is needed on another process. Does this happen naturally when two App Services share a single Plan?
It looks to me like the working set on the low-traffic instance is not being freed up to supply the needs of the high-traffic App Service.
If this is indeed the case, the simple fix is to move them to separate App Service Plans, each with 7gb of memory. However this seems like it might potentially be just shifting the problem around - has anyone else noticed similar issues with multiple Apps on a single App Service Plan? As far as I understand it, these shouldn't interfere with one another to the extent that they all need to be separated. Or have I got the wrong diagnosis?
In some high memory-consumption scenarios, your app might truly require more computing resources. In that case, consider scaling to a higher service tier so the application gets all the resources it needs. Other times, a bug in the code might cause a memory leak. A coding practice also might increase memory consumption. Getting insight into what's triggering high memory consumption is a two-part process. First, create a process dump, and then analyze the process dump. Crash Diagnoser from the Azure Site Extension Gallery can efficiently perform both these steps. For more information.
refer Capture and analyze a dump file for intermittent high memory for Web Apps.
In the end we solved this one via mitigation, rather than getting to the root cause.
We found a mitigation strategy to our previous memory issues several months ago, which was just to restart the server each night using a powershell script. This seems to prevent the memory just building up over time, and only costs us a few seconds of downtime. Our system doesn't have much overnight traffic as our users are all based in the same geographic location.
However we recently found that the overnight restart was reporting 'success' but actually failing each night due to expired credentials. Which meant that the memory issues we were having in the question I posted were actually exacerbated by server uptimes of several weeks. Restoring the overnight restart resolved the memory issues we were seeing, and we certainly don't see our system ever using 10gb+ again.
We'll investigate the memory issues if they rear their heads again. KetanChawda-MSFT's suggestion of using memory dumps to analyse the memory usage will be employed for this investigation when it's needed.
I am on a medium instance which has 3GB of RAM. When I start my webapp the w3wp process starts with say 80MB. I notice that the more time passes this goes up and up.... Now I took a memory dump of the process when it was 570MB and the site was running for 5 days, to see whether there were any .NET objects which were consuming a lot but found out that the largest object was 18MB which were a set of string objects.
I am not using any cache objects since I'm using redis for my session storage, and in actual fact the dump showed that there was nothing in the cache.
Now my question is the following... I am thinking that since I have 3GB of memory IIS will retain some pages in memory (cached) so the website is faster whenever there are requests and that is the reason why the memory keeps increasing. What I'm concerned is that I am having some memory leak in some way, even if I am disposing all EntityFramework objects when being used, or any other appropriate streams which need to be disposed. When some specific threshold is reached I am assuming that old cached data which was in memory gets removed and new pages are included. Am I right in saying this?
I want to point out that in the past I had been on a small instance and the % never went more than 70% and now I am on medium instance and the memory is already 60%.... very very strange with the same code.
I can send memory dump if anyone would like to help me out.
There is an issue that is affecting a small number of Web Apps, and that we're working on patching.
There is a workaround if you are hitting this particular issue:
Go to Kudu Console for your app (e.g. https://{yourapp}.scm.azurewebsites.net/DebugConsole)
Go into the LogFiles folder. If you are running into this issue, you will have a very large eventlog.xml file
Make that file readonly, by running attrib +r eventlog.xml
Optionally, restart your Web App so you have a clean w3wp
Monitor whether the usage still goes up
The one downside is that you'll no longer get those events generated, but in most cases they are not needed (and this is temporary).
The problem has been identified, but we don't have an ETA for the deployment yet.
I am researching into the IIS Application Initialization module and from what I can see, when using the AlwaysRunning option for Start Mode setting for the application pool, basically it starts a new worker process that will always run even if there isn't any requests. When applying this option it starts the process automatically.
My concern is memory management and CPU usage, specifically how is this handled since the process always runs.
How can I compare this to setting the Start Mode to OnDemand and increase the Idle Time minutes to couple of days? That way, I guess, the process will run in idle mode for x days before it's terminated, and reinitialized on the next request and keep running for a couple of days. If I set the minutes to let's say 1.5 days, someone is bound to use the application at least once a day, so it will persist the process runtime and it will never be terminated.
Can anyone share experience regarding this topic?
Thanks
I have multisite application that runs few sites under separate app pools. All are set OnDemand for Start Mode and IdleTime for 1740 minutes, also I use Page Output Cache from app with different times for different page types. There is also NHibernate behind scene and DB is MySql.
The most active site have more than 100k visits per day and almost never is idle. When it starts if I recycle, need 30 seconds to 2 minutes to became full operable depending on requests at the moment and CPU usage is going from 40% to 70%. After the site is up CPU usage is very low (0-4%) if there are no new entries in DB and memory usage is around 3GB when all is cached. Sometimes CPU is going to 20% if at that moment are new request (for not cached content) and there is new entry saving.
Also Page Output Cache works on First Come First Served base so maybe this can also cause little problem while caching is done - user must wait, little more CPU to do the caching.
The most biggest problem in my case is using NHibernate and MySql but Page Output Cache resolved the problem for me when I decided to cache the page modules and content. I realize that is better application to starve for memory then for CPU.
3.5k visitors at one moment when everything is cached gave to me same memory usage (3GB) and CPU (server overall) around 40%
Other sites are using around 1-1.5GB memory and CPU never more then 20% at start.
The application with same settings for app pool and using MSSQL with EF I can't even notice that run on server. It is used by 10-60 users in minute there is not much content except embedding codes and it use 1-5% CPU and never more than 8MB memory. On recycle it is up for less then 10 seconds.
With this my experience I can tell you that all depends on what application serves and how it works :) and how much content do you have.
If you use OnDemand with long IdleTime it will be same as AlwaysStart and process is not used at that moment. If you use OnDemand with short IdleTime more often you will need CPU to start the process.
I have a web site and I am using iis as my web server. I noticed that on production server, the cpu reaches 95% usage pretty fast with very little users. this behaviour I don't see on my developement server. I am using visual studio to develop and iis as my local web server as well.
How much big traffic you have on production comparing to development server? How their parameters compare? Before starting a deep analysis of the application itself, I would identify all the infrastructure and environmental differences. Sometime such problems happens because of some other software, like antivirus software running in the background...
Nevertheless, because it sounds rather as a application problem, I would first check Event Viewer for errors. Then I would start from monitoring a few Performance Counters to correlate % Processor Time counter with Current Connections, Available Memory, # of Exceps Thrown / sec, % Time in GC and so on. This kind of behavior usually has a reason from the list:
excessive loops usage due to some logic error, like calling the same service again and again, trying to load or parse malfunctioned file etc. This can be analyzed with dump analysis (look below).
high CPU usage due to Garbage Collector - when memory usage is extensive (or there is a memory leak even) GC may start to consume more and more CPU fighting with the memory shortage. You will see this with memory-related performance counters.
a considerable amount of exceptions thrown (for example due to some environmental problems like network unavailability, production data difference) can also consume a lot of CPU. Event Viewer and exception-related performance counters (as they can be handled silently by your application) should be a indicator here.
To further analyze your application, I suggest to make a full memory dump during high CPU usage. You can do that with Debug Diag tool. Please refer this IIS troubleshooting guide for details.