I have a Azure Web Site running for 6 months and on Friday 1st April 2016 at 09:50pm the CPU was very high and this had a impact on the performance of the web site. Stopping and restarting the web service solved the problem but it came back at 13:00pm. Since then the CPU has stayed high and making the web site un-useable
I've tried all monitoring tools, Daas, Event Logs, checked for Open Connections and ensure my software is closing or disposing objects correctly.
But the CPU is still high. Only way to resolve is to restart the web service but I dont want to keep doing this.
Has anyone else experience a similar problem and what was the solutions.
The only thing from the event logs that look an issues is the odd "A network-related or instance-specific error occurred while establishing a connection to SQL Server", which could be because the SQL Aure is not available.
Please help
Hmmm, high cpu means that your web site is executing code, perhaps a wrong loop on some not frequent code path.
The brute force way to identify what code is being executed, would be to add tracing to your solution by System.Diagnostics.Trace.WriteLine("I am here") and then check the Azure Application Log.
Another way would be to attach the Visual Studio Debugger during high cpu and check what is being executed
The other way would be to take a dump or minidump from kudu site and analyze it with WinDbg:
1)What thread is conuming cpu:
!runaway
2) What is this thread doing:
!clrstack
hth,
Aldo
Related
since a month one of our web application hosted as WebApp on Azure is having some kind of problem and I cannot find the root cause of that.
This WebApp is hosted on Azure on a 2 x B2 App Service Plan. On the same App Service Plan there is another WebApp that is currently working without any issue.
This WebApp is an ASP.NET WebApi application and exposes a REST set of API.
Effect: without any apparent sense (at least for what I know by now), the ThreadCount metric starts to spin up, sometimes very slowly, sometimes in few minutes. What happens is that no requests seems to be served and the service is dead.
Solution: a simple restart of the application (an this means a restart of the AppPool) causes an immediate obvious drop of the ThreadCount and everything starts as usual.
Other observations: there is no "periodicity" in this event. It happened in the evening, in the morning and in the afternoon. It seems that evening is a preferred timeframe, but I won't say there is any correlation.
What I measured through Azure Monitoring Metric:
- Request Count seems to oscillate normally. There is no peak that causes that increase in ThreadCount
- CPU and Memory seems to be normal, nothing strange.
- Response time, like the others metrics
- Connections (that should be related to sockets) oscillates normally. So I'd exclude something related to DB connections.
What may I do in order to understand what's going on?
After a lot of research, this happened to be related to a wrong usage of Dependency Injection (using Ninject) and an application that wasn't designed to use it.
In order to diagnose, I discovered a very helpful feature in Azure. You can reach it by entering into the app that is having the problem, click on "Diagnose and solve problems" then click on "Diagnostic tools" and then select "Collect .NET profiler report". In that panel, after configuring the storage for the diagnostic files, you can select "Add thread report".
In those report you can easily understand what's going wrong.
Hope this helps.
I deployed an Azure web app back in July and it's been running flawlessly up until about three weeks ago. At that time, I would notice my CPU utilization constantly between 80% to 100%, with no corresponding increase in traffic. The first time I saw this, after concluding it wasn't my app, or increased traffic, causing this, I restarted the web app service and the CPU utilization returned to its normal 5% to 15%. Then after a couple days it started to do it again. And, again, a restart solved the issue.
My question is this. Is this normal to have to restart the web service every day or so? And, if so, why?
Assuming no changes have been made to your code and you have not seen a corresponding increase in traffic, it is not normal. An Azure Web App with no app deployed should almost always stay at 0% CPU utilization. I say "almost always" because Microsoft does run diagnostic and monitoring tools in the background that can cause some very temporary spikes. See here for a thread on that particular issue.
My recommendations are:
When CPU pegs and stays pegged, log into your SCM site. Check the Process Explorer and confirm that it's your w3wp.exe (Note there's a separate w3wp.exe for your SCM site.) that's pegged the CPU.
Ensure that you don't have any Site Extensions or WebJobs that are losing their mind. You can check your installed Site Extensions on the SCM site under the Site Extensions -> Installed tab. Any WebJobs will show up on your SCM process explorer as separate processes from step #1.
Log into the Azure Portal and browse to your Web App's management blade. Go to the Diagnose and Solve Problems blade. From here, you can try "Metrics per Instance" and go through all of the Perf Counters to see if it gives you a clue as to what's wrong. For example, I had SignalR go nuts once and only found it by seeing that my thread count was out of control.
On the Diagnose and Solve Problems blade, you can also check Application Events.
You may have some light shed on this by installing Application Insights on your web application. It has a free tier that will likely have enough space to troubleshoot for a few days. If this is something going bananas with your code, you may get some insight here.
I'm including failed request tracing logs here for completeness. But these would likely show up in Application Insights.
If you've exhausted all of these possibilities, file a support ticket with Microsoft. As the above link shows, they have access to diagnostic tools that we don't and can eliminate the possibility of a runaway diagnostics or infrastructure process. I don't know how much help they can be if the CPU spike is due to your own w3wp.exe that's spiking the CPU.
Of course, if your app is seriously easy to redeploy and it's not a ridiculous hassle, you can just re-provision it and see if you see the same behavior.
UPDATE: I've figured it out. See the end of this question.
I have an Azure App Service running four sites. One of the sites has two deployment slots in addition to the primary one. Recently I've been seeing really high CPU utilization for the App Service plan as a whole.
The dark orange line shows the CPU percentage. This is just after restarting all my sites, which brought it down to this level.
However, when I look at the CPU use reported by each site, it's really low.
The darker blue line shows the CPU time, which is basically nothing. I did this for all of my sites, and all the graphs look the same. Basically, it seems that none of my sites are causing the issue.
A couple of the sites have web jobs, so I took a look at the logs but everything is running fine there. The jobs run for a few seconds every few hours.
So my question is: how can I determine the source of this CPU utilization? Any pointers would be greatly appreciated.
UPDATE: Thanks to the replies below, I was able to get more detail into what was happening. I ended up getting what I needed from SCM / Kudu tools. You can get here by going to your web app in Azure and choosing Advanced Tools from the side nav. From the Kudu dashboard, choose Process Explorer. The value in the Total CPU Time column is not directly useful, because it's the time in seconds that the process has run since it started, which might have been minutes or days ago.
However, if you make a record of the value at intervals, you can look at the change over time, and one process might jump out at you. In my case, it was my WebJobs process. Every 60 seconds, this one process was consuming about 10 seconds of processor time, just within one environment.
The great thing about this Kudu dashboard is, if you can catch the problem while it is actually happening, you can hit the Start Profiling button and capture a diagnostic session. You can then open this up in Visual Studio and get some nice details about where the CPU time is being spent.
Just in case anyone else is seeing similar issues, I'll provide more details about my particular case. As I mentioned, my WebJobs exe was the culprit, and I found that all the CPU time was being spent in StackExchange.Redis.SocketManager, which manages connections to Azure Redis Cache. In my main web app, I create only one connection, as recommended. But Since my web jobs only run every once in a while, I was creating a new connection to Azure Redis Cache each time one ran, which apparently can lead to issues. I changed my code to create the Redis Cache connection once when the WebJob process starts up and use the existing connection when any individual WebJob runs.
Time will tell if this really fixes the issue, but I think it will. When the problem occurred, it always fit the same pattern: After a few days of running fine, my CPU would slowly ramp up over the course of about 12 hours. My thinking is that each time a WebJob ran, it created a connection object, which at first didn't produce trouble, but gradually as WebJobs ran every hour or two, cruft was building up until finally some critical threshold was met and the CPU usage would take off.
Hope this helps someone out there. Best wishes!
May be you should go to webApp scm?
%yourAppName%.scm.azurewebsites.com;
There is a page, that can show you all process, that runned now on your web app. (something like Console > Process).
Also you can go to support page (from scm right corner).
You can find some more info about your performance there, and make memory dump (not for this problem, but it useful for performance issues).
According to your description, I assumed that you could leverage the Crash Diagnoser extension to capture dump files from your Web Apps and WebJobs when the CPUs usage percentage is higher than the specific threshold to isolate this issue. For more details, you could refer to this official blog.
I have an application in the Production environment which is Windows Server 2012/IIS 8 and is load balanced.
Recently out of nowhere, the website app pool suddenly started gettig disabled. The System Windows Logs logged the following error message by the Resource-Exhaustion-Detector ...
Application Pool 'x' is being automatically disabled due to a series of failures in the process(es) serving that application pool.
Windows successfully diagnosed a low virtual memory condition. The following programs consumed the most virtual memory: w3wp.exe (6604) consumed 5080641536 bytes, w3wp.exe (1572) consumed 477335552 bytes, and w3wp.exe (352) consumed 431423488 bytes.
Anyone got any idea how I figure out what is happening? We've never come across this issue before and the application has been running for a good couple of years.
Also, this isn't something that happens regularly but instead seems to happen one every day or so, and even that is at a random time. The Virtual Memory was initially 4GB but because of the issue above, we increased it to 8GB. Recently it spiked at using about 6.8GB out of 8GB, which it has no reason to do so.
Any help would be really appreciated!
The answer is easy here, obviously and certainly you have two issues here
1- You have a serious bug in your process/code that happens intermittently "you need to debug it to find how/when that happens" or at least run a ProcDump
such that you keep it listening on the server on the process W3WP till an exception happens and then analyze this dump to find where the code get stuck and consume that memory/otherwise just debug the code and see what changes were made in last few months "not days"
2- the application get stopped because you have configured/it is configured by default to get disabled break after a certain number of failure repeats, and that's a normal behavior but the main issue as I said is not the application pool itself, its inside the process
please let me know if you need a further explanation or help on this matter
We have a Windows Server 2003 web server, and on that server runs about 5-6 top level Sharepoint sites, with a different application pool for each one.
There is one W3WP process that keeps pegging 100% for most of the day (happened yesterday and today) and it's connected (found by doing "Cscript iisapp.vbs" at the command line and matching ProcessID) to a particular Sharepoint site...which is nearly unusable.
What kind of corrective action can I take? These are the following ideas I had
1) Stopping and restarting the Web Site in IIS - For some reason this didn't stop the offending W3WP process??? Any ideas why not?
2) Stopping and restarting the associated Application Pool.
3) Recycling the associated Application Pool.
Any of those sound like the right idea? If not what are some good things to try? I can't do an iisreset since I don't want to alter service to the other, much more heavily used, Sharepoint sites.
If I truly NEED to do some diagnostic work please point me in the right direction. I'm not the Sharepoint admin guy (he's out of town so I'm filling in even though I'm just a developer) but I'll do my best.
If you need any information just let me know and I'll look it up (slowly though, as that one process is pegging the entire machine).
It's not an IISReset that you need. You have a piece of code that is running amok with your memory. Most likely it's not actually a CPU problem but a paging problem. I've encountered this a few times with data structures in memory that grow too large to page in/out effectively and eventually the attempt to page data just begins consuming everything. The steps I would recommend are:
1) Go get the IIS Debug Diagnostics tools. And learn how to use them.
2) If possible, remove the session state from InProc to a state server or a sql server (since this requires serialization of all classes that go into session this may not be possible). This will help alleviate some process related memory issues.
3) Go to your application pool and adjust the number of worker processes upward. Remove Rapid fail protection (this will allow the site to continue serving pages even if rapid catastrophic errors occur).
The IIS debug diagnostics will record a LOT of data, but you can specify specific "catch" alerts that will detect hangs, excessive cpu usage etc. It will capture gigs of data, so be ready for a long wait when attempting to view the logs.
Turns out someone tried to install some features that went haywire.
So he wrote a stsadm script to uninstall those features
Processor was still pegging.
I restarted the IIS Application Pool for that IIS process, didn't fix it.
So then I restarted IIS for that site and that resolved the processor issue.