Currently after a build/deployment of our app (58 projects, large asp.net MVC 3 front end) takes ~15-20secs to load as it goes through the whole 'recycling the app pool' (release configuration).
We do have a web farm if that alters people's answers, but the question really is:
What are people doing in large scale applications where a maintenance window isn't viable (we're a 24/7 very active website) to minimize that initial 'first hit' on the app pool recycle after a deploy?
We've used a number of tools to analyze that startup time and there doesn't really seem to be any way to bring it down so what I'm looking for are what techniques do people employ in order to minimize the impact of a large application deploy affecting users.
By default - if you change 15 files in an ASP.NET application at once (even via FTP) then the app pool is automatically recycled. You can change the number of files but as soon as web.config and bin files are changed then it needs to recycle. So in my opinion the ideal solution for an environment like yours would be as follows:
4 web servers (this is an arbitrary number)
each server has a status.aspx that the load balancer looks at - use TeamCity to take 2 of these servers "off line" (off the load balancer) and wait 20 seconds for the traffic to filter across. A distributed cache will help keep user experience problems
Use TeamCity to deploy to those 2 servers - run your automated tests etc. and once you are happy put those back into the farm and take the other 2 offline and deploy to those
This can all be scripted / automated. The only issue with this is any schema changes that are not backwards compatible may not allow running the new version site in parallel with old version of the site for the 20 seconds for the load balancer to kick back in
This is good old fashioned Canary Releasing - there are some patterns here http://continuousdelivery.com/patterns/ to help take into consideration. Id also suggest a copy of that continuous delivery book - its like a continuous delivery bible and has got me out of a few situations :)
At the very base you could run a tinyget script against the application after completion of deployment which will "warm up" the application however if a customer hits your site before the script can run, they will still face a delay. What do you currently have in place, what post deployment steps do you have in place?
In a farm environment you could stage deployments too, so take one server out of load balance, update it and then bring that online after deployment and take the other out, complete the deployment and then reintroduce into the farm. How is your SQL Server setup - clustered?
copy and paste from my post here
We operate a Blue/Green deployment strategy on a 4 tier architecture which has a web site over 4 servers at the top tier. Due to the complexity the architecture introduced for deployments, we needed a way to deploy without disturbing any traffic to the "live" site. Following Fowler's advice, but not quite in the same way, we came up with a solution that means we have 2 sites on each server (a blue and a green, or in our case site A and site B). The live site has the appropriate host header, and once we have deployed and tested to the non-live site, we then flip the headers of the 2 sites so that what was once live is now the non-live site, and vice-versa. The effect is, a robust deployment that can be done in business hours and with the highest level of confidence.
This of course complicates your configuration and deployment slightly, but it's worth the effort. I guess it kind of goes without saying that you want to script both the deployment, and the host header swapping.
Firstly, unless you're running Google or something bigger, does a 15-20s load time at 3am for a handful of users really impact that much? I'd say the effort invested in eliminating the occasional lag would far outweigh the 15-20s inconvenience of a couple of users.
I consider it a necessary evil of using ASP.NET unfortunately. Using a pre-compiled site (.DLLs instead of the code-behind files) will lessen the time but not necessarily eliminate it.
The best thing you can do is use something like a status notification bar to warn users they may experience some "issues" during "essential maintenance".
But even then, I'd say in terms of user experience it'd be better to keep quiet and have a handful of people blame their "slow internet" when your site takes 20s to load on one occasion, than announce to all and sundry that it will be slow.
You can also try this approach : http://weblogs.asp.net/scottgu/archive/2009/09/15/auto-start-asp-net-applications-vs-2010-and-net-4-0-series.aspx
without knowing anything about your site, my first thought is that you might be able to break it down into smaller sites so that they start faster individually.
second, with your web farm, i assume you have some sort of load balancing device in front of that from which you can pull machines out of the pool when they are being deployed. don't put them back in the pool until after you have sent a request against the site to get it started up. you should be able to script this such that you are pretty much clicking a button that takes a machine out, deploys to it, and sends a request after it's back up and happy.
You can consider using aspnet_compiler.exe to precompile your application, because I think the delay after deployment is caused by the compilation phase rather than "whole recycling the app pool".
Related
I've been running a Rails app on 1 big dedicated server. Now for scaling I want to switch to a cloud service hoster and serve the app on 3 instances - App, DB and Redis.
I have really bad experience with Heroku performance wise and hence cost efficiency. So for me 2 Alternatives remain: Engineyard and Enterprise-Rails.
What I find important is that Engineyard doesn't offer an autoscaling option to handle peaks. On the other hand Enterprise-Rails doesn't have too much of documentation, most of it is handled by a support crew which is setting up everything.
What are other differences and what should I use for my website? I don't need much of administration work and I am not experienced with it. Basically I just want my Site to run optimally safe, stable and cost efficient without much personal work involved.
I am running a massive Rails app off AWS at this time and I'm really happy with it. Previously I had a number of dedicated boxes that were always causing problems - sooner or later one of them would crash for some reason, Raid failures, database problems whatnot.
At AWS I use RDS for database, elastic cache for caching, I keep all my code on a fat instance that acts as staging server and get a variable number of reserved instances to load the code via NFS.
I also use autoscaling - we've prepaid for a number of reserved instances and autoscaling helps starting up nodes when CPU usage goes above 60%, then removing them when it goes below 25%. autoscaling rules are based on cloudwatch alerts that can be set to monitor a particular group of instances, memcache servers, and so on, you even get e-mails and SMS notifications via SNS when certain scaling activities take place, say when more than 100 instances are spammed in less than 1 hour (massive traffic spike). The instances also get added right up to the load balancers by the way and you don't need to mess with the session store as you can use the sticky session feature which is quite nice.
Recently I also started using a 2nd launch group with spot instances, this complicated things a bit in terms of cloudwatch rules but I'm able to save a lot every month as spot prices are much lower. When the spot price (minimum) I bid is not enough, the set-up I have switches back to reserved instances.
Even more recently I've also started using CloudFront which got my app's page assets to load real fast (about 2 megs of CSS, JS, some icon sprites). Previously I was serving directly from instances via the load balancers.
This took about 20 hours to deploy, test and tune for maximum performance and availability.
One of the problems I have with AWS is that there's no support unless you're prepared to foot a bill. They claim some support is offered without a subscription but the only option in the support area is Billing. Ha. Fortunately it's all stable enough not to put me in a position where I'd have to pay for it.
Overall Rails fits in quite nice with AWS. I spend less than 2 hours per month doing maintenance, where I was spending over 30 previously. Most important for me is that I know that I can GTFO on a vacation for X months knowing nothing will cause any trouble - haven't had a monitoring alert more than a year.
Later edit: the app is a sports site with white labeling feature, lots of users, lots of administrators working on content in the back-end, database intensive as we show market pricing data that should update every few seconds. I had an average load time of about 3 seconds per page with dedicated servers that were doing about the same thing - database, memcache, storage, load balancing, web app. Now my average is under 1 second. Monthly bill is about 8 times lower now.
While Engine Yard doesn't offer auto-scaling (it is in the pipeline), we do have a fairly easy to use scaling feature that allows you to spin up multiple instances at once in times of need.
The advantages over something like Enterprise-Rails is the full documentation, the choice to deploy from the CLI or the dashboard,and our amazing support team. It's also easier to use Engine Yard and move from a personal machine or from another cloud setup than it is using a service such as AWS directly.
I have a question about deploying to an Azure website and I hope someone can help.
Assuming I am running my large-ish website on Azure as a Reserved Mode with 3 instances for scale.
We link up TFS publishing, so we can queue a build and automatically deploy to the server.
My question is: with multiple reserved instance servers, does the deploy do something clever behind the scenes to ensure the site is never down - such as deploying to one server at a time after removing it from the pool and then placing it back into the pool?
Or if the deploy takes a few minutes, are all three servers down at the same time?
If so, what is best practice for deploying updates to a live Azure website server without bringing down the site - albeit briefly?
Background - we're in our R&D stage with Azure, with a plan to move our ecommerce site from in-house hosting to Azure. So far we've done a lot of testing with running on Cloud Services and like the easy way of publishing out to staging, and then being able to quickly flip from staging to release.
However, we would prefer to use websites instead if possible as they eliminate some of the downsides of using Cloud services instead. We cannot afford to have our websites down during each publish though - even if it was for only a small amount of time.
Hope someone can help or point us in the right direction!
Thanks,
Richard.
Have you seen Nir Mashkowski's TechEd video, it's a deep dive into how WAWS works. You can find it on Channel 9. In his session he talked about the storage and domain-resolution process each request goes to.
http://channel9.msdn.com/Events/TechEd/Europe/2012/AZR305
He discussed this on Web Camps TV, too, here: http://channel9.msdn.com/Shows/Web+Camps+TV/Windows-Azure-Web-Sites-Internals-with-Nir-Mashkowski
The files are actually not replicated across each reserved instance. Rather, your files are stored into a drive in WAZ Storage, and those files then served from the instances. This is how the sites can easily be replicated if an instance has issues, becomes overloaded, or in the most typical case - when you want to scale out to multiple instances.
So when your code is published it really only lands on one drive, then served from the instances. Nir's talks does the process a much better job than my description, so check that out for more in-depth details.
I'm about to start development on a project with very uncertain load/traffic specifics. When it will be released there will certainly be very low load that can easily be handled by a single desktop quad code machine.
The problem is that there will be (after some invite-only period) a strong publicity for the product so I expect considerable traffic/load peaks.
I haven't read enough about cloud providers and I'm mostly leaning toward Amazon or Azure for the credibility these two companies have without checking them out as I should with others (ie. Rackspace that I suppose is also a cloud service provider).
What I want
I would like to create a normal Asp.net MVC web application that can be run on in-house single machine low-cost server. It would run web server along with database (relational and maybe also document) and fulltext search (not SQL FTS but rather high speed separate product like Lucene or Sphinx). But after initial invite-only period I'd like to move this app to the cloud to make it more traffic/load demand-friendly.
As much as I know Amazon offers a sort of virtual machine hosting which I understand you setup as a normal server but has possible flexible resources in terms of load power. I'm not sure if that can be accomplished on Azure as well.
Questions
What is your experience with application transition to cloud and which one did you choose and why?
What would you recommend I should think about when designing/developing the solution to make the transition as painless as possible.
Based on your experience is it better to move to the cloud (financial wise) or is it better to buy your own servers and load balance application yourself and maybe save money on the long run?
"Cloud" is such a vague term. Still, I think this is a very good question.
Basically, IaaS cloud hosting does not magically make your application scale. It's really a virtual private server with very short contract / cancellation periods.
For scalability, the magic lies not so much in the hosting, but in the horizontal scalability of the application code itself. This is related to all the distributed computing challenges. For example, adding more application servers is not always easy: you must be sure that you don't persist any user state in the server application (but rather in a database, static can be evil), caching can be problematic because local caches can make the situation worse if you're using a round-robin strategy, etc.
What is your experience with application transition to cloud and which one did you choose and why?
What would you recommend I should think about when designing/developing the solution to make the transition as painless as possible.
You don't really have to do anything different just to host on EC2 or Azure -- basically. But of course, it's not that easy when things grow.
For instance, EC2 instance storage is rather limited. Additional storage on EBS, however, does not provide comparable performance characteristics and can be a bit more laggy than a disk. The point here is that EBS does magically scale, and it's probably more PaaS than IaaS; but it's not a simple hard disk and it does, consequently, not behave like a hard drive. I don't know about Azure block storage. In general, expect additional abstraction layers to introduce problems of their own, no matter what they do.
Based on your experience is it better to move to the cloud (financial wise) or is it better to buy your own servers and load balance application yourself and maybe save money on the long run?
Typical cloud providers are more expensive than the usual 'round-the-corner VPS providers, but they are, to my experience, also much more reliable and professional. EC2 has a free tier (but it's quite small), Azure gives you a small instance for free for 3 months.
Doing the calculation right is rather tricky; for example, if you have to shut down your service for whatever reason, it's nice to be able to cancel now rather than pay another year - you might want to put this risk into your calculation. On the other hand, both EC2 and Azure will be considerably cheaper if you sign up for 6 or 12 months, rather than paying by the hour.
You might want to check out the free Azure plan, because it's nice to start fiddling around without any cost. A big advantage of cloud providers is that you can scale vertically very easily: buying a 16 core, 64GB RAM server machine is really expensive, but if there's so much traffic on your site, upgrading your plan won't be such a big issue.
As someone hasn't mention it yet...
AppHarbor has been amazing. You can push stuff in a matter of minutes. Deployment is a breeze. And setting up your project for it is easier as well. And it doesn't even require any major changes in your solution to fit in.
For the full-text search, you might consider something like Websolr.
A lot of this depends on what your app is doing (e.g., are there separable components that might benefit from running on different instances, vs. a simple CRUD application with a front end). One thing to consider is that in a cloud application you normally don't have a traditional relational database. As such, you have to choose either cloud or traditional hosting, or plan on coding your access layer twice. Azure does have relational databases (SQL Azure), although they're not identical to SQL Server 2008R2. You're going to have to research the pros/cons of a cloud setup for your specific situation.
As far as financial concerns, it's usually a lot cheaper to just get an account with a hosting company instead of a cloud service, since you pay by the month, instead of the hour (last time I checked an account with Azure running 24/7 for a month would cost about $40-$50, while you can get hosting for $15 a month). The savings with the cloud come in when you have to run several servers, and the cost of maintaining them surpasses the cost of the instance on the cloud platform.
So, sorry, there's no silver bullet answer for you. Read up on the different services available. Consider what your application needs, what prices will be, and go from there.
I have just migrated an MVC-based application from a dedicated server to Azure. When migrating the MSSQl-database, I first tried importing .bacpak files but some of the tables failed because of their size. I then used the SQL Database migratio wizard which worked fine for small tables but failed for tables with BLOB-fields. For these tables I had to use temporary intermediate tables. Then after a while after all the data was transferred setting up the Webapp was a breeze and we went in production. At first, everything seemed to work just fine, but after a couple of hours when the load got heavier, all kind of errors occurred. I went into the Azure portal and it was really easy to see the
I have an ASP.NET MVC 3 application, WouldBeBetter.com, currently hosted on Windows Azure. I have an Introductory Special subscription package that was free for several months but was surprised at how expensive it has turned out to be (€150 p/m on average!) now that I have started paying for it. That is just way too much money for a site that is not going to generate money any time soon so I've decided to move to a regular hosting provider (DiscountASP.Net).
One of the things I'll truly miss though, is the separated Staging and Production environments Azure provides, along with the zero-downtime environment swap.
My question is, how could I go about "simulating" a staging environment while hosting on a traditional provider? And what is my best shot at minimizing downtime on new deployments?
Thanks.
UPDATE: I chose the answer I chose not because I consider it the best method, but because it is what makes the most sense for me at this point.
Before abandoning Windows Azure, there are several cost-saving things you can do to lower your monthly bill. For instance:
If you have both a Web role and a Worker role, merge the two. Take your background processing, queue processing, etc. and run them in your Web role (do your time-consuming startup in OnStart(), then just add a Run() override to call queue-processing, etc.
Consider the new Extra Small instance, which costs just under half of a Small instance
Delete your Staging deployment after you're confident your production code is running ok. Keep the cspkg handy though, in blob storage, so that you could always re-deploy it.
I use DiscountASP myself. It's pretty basic hosting for sure, a little behind the times. But I have found just creating a subdirectory and publishing my beta/test/whatever versions there works pretty well. It's not fancy or pretty, but does get the job done.
In order to do this you need to create the subdirectory first, then go into the control panel and tell DASP that directory is an application. Then you also have to consider that directory's web.config is going to be a combination of its own and the parent one. You also have to consider robots.txt for this subdirectory and protecting it in general from nosy people.
You could probably pull this off with subdomains too, depending on how your domain is set up.
Another option: appharbor? They have a free plan. If you can stay within the confines of their free plan, it might work well (I've never used them, currently interested in trying them though)
1) Get an automated deployment tool. There are plenty of free/open-source ones that million/billion dollar companies actually use for their production environments.
2) Get a second hosting package identical to the first. Use it as your staging, then just redeploy to production when staging passes.
I am curious on how others manage code promotion from DEV to TEST to PROD within an enterprise.
What tools or processes do you use to manage the "red tape", entry/exit criteria side of things?
My current organisation is half stuck between some custom online forms type functionality and paper based dependencies to submit documents, gather approvals and reviews.
All this is left in the project managers hands to track what has been submitted, passed review, approved and advise management if there are any roadblocks that may need approval to be "overlooked" before an application can be promoted to the next environment.
A browser based application would be ideal... so whats out there? please show me that you googlefu is better than mine.
It's hard to find one that's good via google. There is a vast array of tools out there for issue management so I'll mention what we use and what we woudl like to use.
We currently use serena products. They have worked well for us in the past. Team Track is our issue management and handles the life cycle of any issue we work on. Version Manager is our source control and has the feature of implementing promotional groups like DEV TEST And PROD. We use DEV, TSTAGE, TEST, PSTAGE and PROD to signify the movement from one to the other, but it's much the same. The two products integrate nicely so that the source associated with the issues is linked, but we have no build process setup in this environment. It's expensive, but it works well.
We are looking ot move to a more common system using Jira for issue management, Subversion for source control, Fisheye to link the two together and Cruise Control for build management. This is less expensive, totaling a few thousand for an enterprise lisence and provides all the same features but with the added bonus of SVN which is a very nice code version mangager.
I hope that helps.
There are a few different scenarios that I've experienced over the years:
Dev -> Test : There is usually a code freeze date that stops work on new features and gets a test environment the code that has been tagged/labelled/archived that gets built. This then gets copied onto the machines and the tests go fine. This is also usually the least detailed of any push.
Test->Prod : This requires the minor change that production has to go down which can mean that a "gone fishing" page goes up or IIS doesn'thave any sites running and the code is copied over again. There are special cases to this where a load balancer can act as a switch so that the promotion happens and none of the customers experience any down time as the ones on the older server will move once their session ends.
To elaborate on that switch idea, the set up is to have 2 potentially live servers with just one server taking requests that the load balancer just sends all the traffic to one machine that can be switched when the other server has the updated code to go live.
There can also be a staging environment which is between test and production where the process is similar in terms of there is a set date when the promotion happens.
Where I used to work there would be merge days where a developer spent most of a day in Perforce merging code so that it could be promoted from one environment to another.
Now there are a couple of cases where this isn't used:
"Hotfixes" or "Hot patches" would occur where I used to work and in this case the specific files were copied up into the staging and production environments on its own since the code change had to get into Production ASAP since something broke in production or some new thing that had to get done that takes 2 minutes gets done. In this case, the code change getting pushed in had to be reviewed and approved before going out.
Those are the different approaches I've seen used where generally there are schedules and timelines potentially have to be changed or additional resources brought in to make a hard date like if a conference is on a particular weekend that such and such is ready for that.
Of course in a few places there has been the, "Oh, was that broken? Let me see..." and a few minutes later, "No, see it isn't broken for me," where someone changed things without asking permission or anything where a company still has what they call "cowboy programming."
Another point is the scale of the release:
1) Tiny - This is the case where one web page goes up so that user X can do Y.
2) Small - A handful or so of files that isn't really complicated but isn't exactly trivial.
3) Medium - Where going from one environment to another requires changing a bunch of files and usually has scripts to move.
4) Big - Where there are scheduled promotions and various developers are asked for who is taking which shifts when the live push is done. I had this in a case where there was a data migration to do in addition to a release of some new e-commerce sites.
5) Mammoth - Where everything is brand new including how this would be used. I don't think I've ever seen one of this size but I'd imagine Microsoft or Google would have releases of this size.
Somewhere in that spectrum most releases fall and so how much planning and preparation can vary quite a bit and let's not forget that regulatory compliance can be its own pain in getting some things done.