I believe that the mvc mini profiler is a bit of a 'God-send'
I have incorporated it in a new MVC project which is targeting the Azure platform.
My question is - how to handle profiling across server (role instance) barriers?
Is this is even possible?
I don't understand why you would need to profile these apps any differently. You want to profile how your app behaves on the production server - go ahead and do it.
A single request will still be executed on a single instance, and you'll get the data from that same instance. If you want to profile services located on a different physical tier as well, that would require different approaches; involving communication through internal endpoints which I'm sure the mini profiler doesn't support out of the box. However, the modification shouldn't be that complicated.
However, would you want to profile physically separated tiers, I would go about it in a different way. Specifically, profile each tier independantly. Because that's how I would go about optimizing it. If you wrap the call to your other tier in a profiler statement, you can see where the problem lies and still be able to solve it.
By default the mvc-mini-profiler stores and delivers its results using HttpRuntime.Cache. This is going to cause some problems in a multi-instance environment.
If you are using multiple instances, then some ways you might be able to make this work are:
to change the Http Cache to an AppFabric Cache implementation (or some MemCached implementation)
to use an alternative Storage strategy for your profile results (the code includes SqlServerStorage as an example?)
Obviously, whichever strategy you choose will require more time/resources than just the single instance implementation.
Related
I'm curious how auto scaling works with an Azure web application, specifically how each new instance gets a copy of the source code for the application.
Is this what happens, or is the source stored somewhere and each new instance points to it?
The entire virtual machine is duplicated. So usually you might have just one database but multiple apps receiving and processing the requests. If you need an "autoscaling" database too, then there are database solutions that handle syncronization across multiple machines, but in that case you're probably better off using Azure's native database which takes care of that.
I am conducting some research on emerging web technologies and have created a very simple Azure website which makes use of web sockets and mongo db as the database. I have managed to get all the components working together and now must perform load testing on the application.
The main criteria is the maximum user load that the app can support, at the moment there is 1 web role instance, so probably I would need to test the max user load for that instance, then try with 2 instances and so on.
I found some solutions online such as Loadstorm, however I cannot afford to pay to use these services so I need to be able to do this from my own development machine OR from another cloud service.
I have come across Visual Studio Load Tests and they seem quite useful, however it seems they require VS Ultimate and an active msdn subscription - the prerequisites are listed here. Also, from this video which shows the basics of load tests, it seems like these load tests are created completely separately from the actual web project, so does that mean I can only see metrics related to the user? i.e. I cannot see the amount of RAM being used, processor etc.
Any suggestions?
You might create a Linux virtual machine in Azure itself or another hosting provider and use ApacheBench (ab) or JMeter to do simple load testing on your application. Be aware that in such a setup your benchmark servers may be a bottleneck themselves.
Another approach is to use online load testing services wich allow some free usage, such as:
loader.io, by SendGrid Labs
LoadStorm
Blazemeter
Blitz
Neotys
Loadimpact
For load-testing, LoadStorm is very reasonably priced, especially compared to on-premises software (and has a free tier with up to 25 virtual clients). You can install code such as jmeter, but you'll still need machines (or vm's) to host and run it from, and you need to make sure that the load-generator machines aren't the bottleneck in your tests.
When you run your tests, you may want to consider separating your web tier from MongoDB. MongoDB will consume as much memory as possible (as that's what gives MongoDB its speed). In a real-world scenario, you'll likely have MongoDB in its own environment. So for your tests, I'd consider offloading MongoDB to its own instance(s), and 10gen has a Worker Role setup that's fairly straightforward to install.
Also remember that NIC bandwidth is 100Mbps per core, which could be a limiting factor on your tests, depending on how much load you're driving.
One alternative to self-hosting MongoDB: Offload MongoDB to a hoster such as MongoLab. This will allow you to test the capacity of your web app without worrying about the details around MongoDB setup, configuration, optimization, etc. Currently MongoLab offers their free tier hosted in Azure, US West and US East data centers.
Editing my response, didnt read the question carefully.
Check out this thread for various tools and links:
Open source Tool for Stress, Load and Performance testing
If you are interested in finding the performance counters of the application under test you can revisit some of the latest features added to Visual Load Cloud base load test.
http://blogs.msdn.com/b/visualstudioalm/archive/2014/04/07/get-application-performance-data-during-load-runs-with-visual-studio-online.aspx
To get more info on Visual Studio Cloud Load Testing solution - https://www.visualstudio.com/features/vso-cloud-load-testing-vs
I've been reading about azures storage system, and worker roles and web roles.
Do you HAVE to develop an application specifically for azure with this? It looks like you can remote desktop into azure and setup an application in IIS like you normally can on a windows server, right? I'm a little confused because they read like you need to develop an azure specific application.
Looking to move to the cloud, but I don't want to have to rework my application for it.
Thanks for any clarification.
Changes to the ASP.NET application are minimal (for the most part the web application will just work in Azure)
But you don't remote connect to deploy. You actually build a package (zip) with a manifest (xml) which has information about how to deploy your app, and you give it to Azure. In turn, Azure will take care of allocating servers and deploying your app.
There are several elements to think about here -
Code wise - to a large degree this is 'just' .net running on IIS and Windows, so everything is very familiar and all the past learnings, best-practices, etc. apply.
On top of that you may want to leverage some Azure specific capabilities - for example table storage, or queues, or interacting with your deployment - for which you might need to learn a few more APIs, but these aren't big, and are well thought of and kept quite simple, so there's not a bit learning curve. good architecture, of course, would look to abstract these away to prevent/reduce lock-in, but that's a design choice.
Outside the code, however, there's a bit more to think about -
You'd like to think about your deployment - because RDP-ing into a machine and making changes that way takes away many of the benefits of PaaS - namely the ability of the platform to 'self-heal' by automatically re-deploying your application should a server fail.
You would also like to think about monitoring - which would need to be done slightly differently.
Last - cloud enables different scenarios, and provides a scale-out model rather than a scale-up model, which you might want to take advantage of, but it might require doing things a little bit.
So - bottom line - yes - you could probably get an application in Azure very quickly, without really having learning much or anything, but to do things properly, and to really gain from the platform, you'd like to learn a bit more about it. good thing is - it's not much, and it all feels very familiar, just another 'framework' for .net (and Java, amongst others....)
You can just build a pretty vanilla web application with a SQL backend and get it to work on Azure with minimal Azure dependencies. This application will then be pretty portable to another server or cloud platform.
But like you have seen, there are a number of Azure specific features. But these are generally optional and you can do without them, although in building highly scalable sites they are useful.
Azure is a platform, so under normal circumstances you should not need to remote desktop in fiddle with stuff. RDP is really just for use in desperate debugging situations.
i intend to build software for SMEs on the azure platform that can be provisioned for different clients..what i mean is, once the client signs up, a new instance is automatically created for them on the azure platform.
Does anyone have any experience with building such solutions or are their any commercial packages like that available?
thanks
It sounds like you're planning to have a single-tenant system, where each instance is slightly different then others and is customized for each client slightly differently. If this is the case, Azure in general will not be a great platform for you. It thrives on providing a dynamic quantity of exactly-alike instances. Furthermore, having one instance per client is a bad idead, as instances are slightly volatile. MS may choose to bring one down for an upgrade, or instance may simply crash, and SLA is only inforced when 2+ instances are running.
I'd like to suggest that you consider multi-tenant environment, where your system shards itself virtually via database/architecture/etc. Do not tie instances to quantity of clients, but to actual load.
Now, if you want to spin up exactly same instances when new clients sign up, check out dynamic scaling service for Azure called AzureWatch # http://www.paraleap.com - its main premise to scale your instances to load, but with a few simple queue/table inserts it can programmatically scale you up or down. Contact me there if you think this will work for you, and ill be glad to explain how this can be done
I'm hoping someone can validate or correct my conclusions here.
I'm looking into writing a small side project. I want to create a desktop application for taking notes that will synchronise to a web-server so that multiple installations can be kept in step and data shared and also so that it can be accessed via a browser if necessary.
I've kind of been half-listening to the noises about CouchDB and I've heard mention of "offline functionality", of desktop-couchdb and of moves to utilise its ability to handle intermittent communications to enable distributed applications in the mobile market. This all led me to believe that it might be an interesting option to look at for providing my data storage and also handling my synchronisation needs, but after spending some time looking around for info on how to get started my conclusion is that I've got completely the wrong end of the stick and the reality is that:
There's no way of packaging up a CouchDB instance, distributing it as part of a desktop application and running it in the context of that application to provide local storage and synchronisation to a central database.
Am I correct here? If so is there any technology out there that does this sort of thing or am I left just rolling my own local storage and maybe still using CouchDB on the server?
Update (2012/05): check out the new TouchDB projects from Couchbase if you are targeting Mac OS X and/or iOS or Android. These actually use SQLite under the hood (at least for now) but can replicate to/from a "real" CouchDB server. Another clientside alternative that is finally starting to mature is PouchDB, which runs in IndexedDB capable browser engines. Using these or using them to inspire similar port to another desktop platform is now becoming a better-trod path.
Original answer:
There's no way of packaging up a
CouchDB instance, distributing it as
part of a desktop application and
running it in the context of that
application to provide local storage
and synchronisation to a central
database.
At this point in time, your statement is practically correct although it is possible to include CouchDB in an app — for an example see CouchDBX.app which is a thin wrapper around a prefixed bundle of CouchDB and all its dependencies.
The easiest way to build a CouchDB app is to assume that the user will already have a CouchDB server running. This is easier than it sounds, especially with Couchone's hosting or a prebuilt app like CouchDBX on OS X or DesktopCouch on Ubuntu. This latter is especially interesting, because if I understand correctly it is included by default with Ubuntu these days, and automatically spins up a CouchDB server per-user when you query its port via D-Bus. Something similar could (and should) be done on OS X using launchd and Bonjour.
So as you write, you either would design your app to store data in a local format and optionally sync with a CouchDB service you provide or you'd have to build and bundle all of Erlang, SpiderMonkey and CouchDB together with your app along with some scripts to make sure it was running when needed. This is possible but obviously neither of these are ideal, and believe me you're not the only one wanting a simpler solution for desktop-oriented apps!