Whats is load testing ? Give me the techniques or process for load testing ? Why my website is very slow ?
Whats is load testing ?
Load testing a website is the process of subjecting the site to multiple simultaneous users (usually simulated via a testing tool) and measuring the performance.
Give me the techniques or process for load testing ?
There is no short answer to that. There are many processes, techniques and tools involved in website load testing.
Why my website is very slow ?
Bandwidth limitations, CPU overload, poor code design, database locking, memory contention...could be any of those and a zillion other possibilities. You'll need to do some testing to narrow it down.
Judging by your questions, you've never done any performance testing before, so you might want to engage some help. My company as well as many others offer load testing services that can get answers for you quickly.
Related
Is caching considered a standard practice or is it only necessary as traffic grows? It is not a retail site, simply information sharing for an organization with likely no more than a few hundred members anytime soon.
Additionally, it would require some memcache plugin on heroku, and while most of them do have a free package, I am not sure when that would be reached.
Choosing to use caching or not belongs to you. If your server specs as tight and you expect sometimes pick of traffic and you need to keep your application highly responsive then caching may help to improve response times.
But it's not mandatory and it ad up code to write, test, and maintain. So if you don't need it it could be a time consuming task. Choice is yours.
As for Heroku I let someone with more knowledge than me answer to you
I need to develop an e-commerce site for my client.
He wants it to be very fast (1.25 second or less for each page).
I've had my criterion - 3 seconds.
So 1.25 second is very challenging.
He showed me a website that loads very fast.
http://www.papayaclothing.com/shop/
It's impressive.
I will develop with Spree e-commerce solution (Ruby on Rails).
However, I don't think Ruby on Rails can perform that fast.
Any advice for me?
Thanks.
Sam
Because this is a vast subject, this answer is a community wiki, feel free to improve this answer
Website loading speed depends of many factor : language, framework, DB, CPU, RAM, caching, ...
By the way, the whole thing depends of the worse element. I don't think that Ruby or Rails are the limiting factors here.
To start you can see if Spree is a good framework. Here is a benchmark of Spree in different hosting and comparing to a pure Rails app : http://blog.endpoint.com/2011/05/spree-performance-benchmarking.html
As you can see, this go from 0.5s to 6s ! You can notice that Spree version inpacts a lot on performance. Unfortunately last versions are not on the benchmark... You should try to find an up to date benchmark. You can also notice that a raw rails app is, at first sight, faster.
Next you have to review your hardware : what is your server ? Dedicated or not ? How many CPU and RAM ? Can you increase ?
I think DB is also a thing to watch for a e-commerce case, because I can imagine you have a lot of products. So you can test different DB engines, and see in Spree community what is the recommended one.
Next you can interest you in caching : http://guides.rubyonrails.org/caching_with_rails.html
To go further you can try some memcached store for your putting your cache in RAM : http://guides.rubyonrails.org/caching_with_rails.html#activesupport-cache-memcachestore
Find slowest actions (New Relic is great and their RPM Lite is free though it only reports over last 30 min) and analyze to see if they are render-heavy or db-heavy. My guess would be that your case is db-heavy.
If that's the case, then optimize your queries with eager loading eliminating n+1 problems as well as making sure that only relevant data is returned, e.g. don't do User.all if you only need username and email.
Then you should cache whatever you can, e.g. where real-time data is not crucial.
For more info: http://asciicasts.com/episodes/202-active-record-queries-in-rails-3
and
http://synaptify.com/?p=106
You have a few options here, mentioned in the previous answers.
For client side performance improvements, I'd highly recommend WebPagetest, YSlow, and Yahoo's Best Practices for Speeding Up Your Web Site as good resources.
For strictly Rails performance, I'd suggest Rails' docs on caching (already suggested). I frequently use Rails low level caching. Full page caching can apply to some types of pages, but typically do not work for product pages if you have inventory that fluctuates a lot.
Spree has some performance issues because it is a generic ecommerce solution with many features that you may not use that add bloat. Make sure you have database indexes and consider pursuing profiling server processes to see what's run the most & takes the most time. It's highly probably that you will need to override some of Spree's functionality to speed things up.
Finally, Google considers 0.25 seconds to be the standard for a speedy website.
I'm looking for tools to monitor/test performance in rails, and I'm not having much luck finding anything particularly effective. I've read the rails 'performance' guide, but I use RSpec instead of Rake:Test, so I'm not particularly keen to use the rake:test framework.
So, what do folks use for performance testing in rails apart from the rake:test benchmarker? Any suggestions appreciated
Performance benchmarking is one of those things that you'll get different opinions about depending on who you ask. One thing I hear over and over is that you shouldn't obsess over performance early on. I'm not sure where you're at with your application, but this could be something to consider. After developing a rather large application, I can honestly say I agree with them. It's better to use good practice when developing and wait to do performance tuning at a later time. Best practices include things like indexing database columns.
For performance monitoring of live Rails applications, New Relic is one of the best tools out there*. The free plan is a little limited as it only provides 30 minutes of historical data, but the information it collects is priceless. Some of the cloud hosts like Heroku and Engine Yard are offering free bronze plan upgrades, which stores a week of data. Once you have information about your application, you can make educated decisions about where to focus your time.
* My opinion
When your app needs some performance testing, the default TestUnit based performance benchmarking tests are a great start. However, you shouldn't stop there, and should consider using a variety of tools based on the nature of your application.
For example, analyzing production logs using a tool like the request-log-analyzer is a great way to identify the real performance bottlenecks. Bullet is another great tool you can run in your development environment to identify performance inefficiencies in your database calls. For low level benchmarking, rails also gives you the benchmark helper methods in models, controllers and views. This can be handy if you are focusing on tuning some specific part of your application.
It is also worth noting that rspec is not the best tool for benchmarking performance (to date). In my opinion, trying to assert things like it should_take_less_than 50 is stretching the idea of performance testing and trying to force it into the concept of BDD. Performance is less often about absolute expectations and more about identifying the slowest parts of your app and making them faster.
There are many online resources on the topic. I've found these railscasts to be a great starting point:
http://railscasts.com/episodes/368-miniprofiler (free)
http://railscasts.com/episodes/411-performance-testing (pro, requires subscription)
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QUICK QUESTION: Does Grails take too much resources for high traffic website, and is it expensier to host?
For example: if I can make a site that has millions of users/m easier in CakePHP does it worth to make it in Grails just to save some webserver resources- or will it need more servers?
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Hello,
I know there are a lot of similar questions on the net, but because I am a newbie in web development I didn't find the solution for my specific problem.
I am planing on creating a flash games portal from scratch. It is a big chance that there will be big traffic from the beginning (millions of pageviews). I want to reduce the server costs as much as possible but in the same time to not be tide to an expensive contract as there is a chance that the project will not be as successfully as I want and in that case the money would be very little.
The question is : what technology to use? I don't know any web dev technology yet so it doesn't matter what I will learn. My web dev experience is a little php 8 years ago, and from then I programmed in C++ / Java- game and mobile development. I like Java and C syntax and language very much and I tend to dislike dynamic typing or non robust scripting (like php)- but I can get along if these are the best
choices.
The candidates are now: -
Grails (my best for now)
Ruby on Rails
Cake PHP
Other technologies (Google App
Engine, Python/Django etc...)
I was considering at first using pure C and compiling the web app in the server- just to squeeze more from the servers, but soon I understand that this is overkill.
Next my eyes came on Ruby - as there is a lot of buzz for it's easiness of use. Next I discovered Grails and looked at Java because it is said that it is "faster". But I don't know what this "Faster" really means on my needs, so here comes the first question:
1) What will be my biggest consumption on the server, other than bandwidth, for a lot of flash content requests? Is it memory? I heard that Java needs a lot of memory, but is faster. Is it CPU? I am planning to take some daily VPS.NET nodes at first, to see if there is a demand, and if the "spike" is permanent to move to a dedicated server (serverloft.com has some good offers), else to remain with less nodes.
I was also considering developing in Google App Engine- cheap or free hosting to use at first - so I can test my assumption- and also very easy to use (no need for sys administration) but the costs became high if used more (> 3 million games played / month .. x mb/ each). And the issue with Google is that it looks me in this technology.
My other concern is scalability (not only for traffic/users, but as adding functionality) My plans are to release a functional site in just 4 weeks (just the basics frontend and some quick basic backend - so I can be able to modify some things and add games manually) - but then to raise it and add more things to it. I am planning to take a little different approach than other portals so I need to write it from scratch (a script will not do).
2) Will Grails take much more resources than RoR or Php server wise? I heard that making it on Java stack will be hardware expensive and is overkill if you don't make a bank application. My application will not be very complex (I hope and i will try to) but will have a lot of traffic.
I also took in account using CDN for files, but the cheapest CDN found was 5c/GB (vps.net) and the cost per gb on serverloft (http://www.serverloft.com/dedizierte-server/server-details.php?products=4) is only 1.79 cents/GB and comes with the other resources either.
I am new to this domain (web). I am learning the ropes and searching on the web for ~half of year but don't have any really practical experience, so I know that I must have some naive thinking and other issues that i don't know from now, so please give me any advice you want regarding anything, not just the specific questions asked.
And thank you so much for such great community!
This is how I (on my blog) view web performance, especially for highly abstracted frameworks like Grails.
I don't understand the obsession with
runtime performance. Given most
project scenarios your primary focus
should be on your performance, as in
your ability to get things done with a
chosen technology.
For example, you will get more done in
a given period of time with Groovy
than with Java any day. Often one line
of Groovy code will equate to 10 lines
of Java code etc etc
Very rarely will byte code execution
time be your performance issue, most
often its...
Bad algorithm implementation or
design. Bad DB design and / or queries.
Taking to long to get things done and
then having all sorts of commercial
relationship issues because of it.
With web applications you are usually
not performing lots of long running
CPU bound operations. Most of your
request / response time is spent in
the wire (internet routing etc) and in
the DB (executing queries).
Choose a technology that takes a load
off your mind and one that frees you
from writing mountains of boiler plate
code, so that you can rather
concentrate on designing and
implementing good algorithms, DB's and
queries etc etc
I've heard that people say that they've made a scalable web application..
What really is scaling?
What can be done by developers to make their application scalable?
What are the factors that are looked after by developers during scaling?
Any tips and tricks about scaling web applications with asp.net and sql server...
What really is scaling?
Scaling is the increasing in capacity and/or usage of your application.
What do developers do to make their application scalable?
Either allow their applications to scale vertically or horizontally.
Horizontal scaling is about doing things in parallel.
Vertical scaling is about doing things faster. This typically means more powerful hardware.
Often when people talk about horizontal scalability the ideal is to have (near-)linear scalability. This means that if one $5k production box can handle 2,000 concurrent users then adding 4 more should handle 10,000 concurrent users. The closer it is to that figure the better.
The ideal for highly scalable apps is to have near-limitless near-linear horizontal scalability such that you can just plug in another box and your capacity increases by an expected amount with little or no diminishing returns.
Ideally redundancy is part of the equation too but that's typically a separate issue.
The poster child for this kind of scalability is, of course, Google.
What are the factors that are looked after by developers during scaling?
How much scale should be planned for? There's no point spending time and money on a problem you'll never have;
Is it possible and/or economical to scale vertically? This is the preferred option as it is typically much, much cheaper (in the short term);
Is it worth the (often significant) cost to enable your application to scale horizontally? Distributed/multithreaded apps are significantly more difficult and expensive to write.
Any tips and tricks about scaling web applications...
Yes:
Don't worry about problems you'll never have;
Don't worry much about problems you're unlikely to have. Chances are things will have changed long before you have them;
Don't be afraid to throw away code and start again. Having automated tests makes this far easier; and
Think in terms of developer time being expensive.
(4) is a key point. You might have a poorly written app that will require $20,000 of hardware to essentially fix. Nowadays $20,000 buys a lot of power (64+GB of RAM, 4 quad core CPUs, etc), probably more than 99% of people will ever need. Is it cheaper just to do that or spend 6 months rewriting and debugging a new app to make it faster?
It's easily the first option.
So I'll add another item to my list: be pragmatic.
My 2c definition of "scalable" is a system whose throughput grows linearly (or at least predictably) with resources. Add a machine and get 2x throughput. Add another machine and get 3x throughput. Or, move from a 2p machine to a 4p machine, and get 2x throughput.
It rarely works linearly, but a well-designed system can approach linear scalability. Add $1 of HW and get 1 unit worth of additional performance.
This is important in web apps because the potential user base is ~1b people.
Contention for resources within the app, when it is subjected to many concurrent requests, is what causes scalability to suffer. The end result of such a system is that no matter how much hardware you use, you cannot get it to deliver more throughput. It "tops out". The HW-cost versus performance curve goes asymptotic.
For example, if there's a single app-wide in-memory structure that needs to be updated for each web transaction or interaction, that structure will become a bottleneck, and will limit scalability of the app. Adding more CPUs or more memory or (maybe) more machines won't help increase throughput - you will still have requests lining up to lock that structure.
Often in a transactional app, the bottleneck is the database, or a particular table in the database.
What really is scaling?
Scaling means accommodating increases in usage and data volume, and ideally the implementation should be maintainable.
What developers do to make their application scalable?
Use a database, but cache as much as possible while accommodating user experience (possibly in the session).
Any tips and tricks about scaling web applications...
There are lots, but it depends on the implementation. What programming language(s), what database, etc. The question needs to be refined.
Scalable means that your app is prepared for (and capable of handling) future growth. It can handle higher traffic, more activity, etc. Making your site more scalable can entail various things. You may work on storing more in cache, rather than querying the database(s) unnecessarily. It may entail writing better queries, to keep connections to a minimum, and resources freed up.
Resources:
Seattle Conference on Scalability (Video)
Improving .NET Application Performance and Scalability (Video)
Writing Scalable Applications with PHP
Scalability, on Wikipedia
Books have been written on this topic. An excellent one which targets internet applications but describes principles and practices that can be applied in any development effort is Scalable Internet Architectures
May I suggest a "User-Centric" definition;
Scalable applications provide a consistent level of experience to each user irrespective of the number of users.
For web applications this means 24/7 anywhere in the world. However, given the diversity of the available bandwidth around the world and developer's lack of control over its performance and availability, we may re-define it as follows:
Scalable web applications provide a consistent response time, measured at the server TCP port in use, irrespective of the number of requests.
To achieve this the developer must avoid or remove all performance bottle-necks. Currently the most challenging issue is the scalability of distributed RDBMS systems.