Server responding to request differnetly

Question

I believe as above hosted locally , the long green delay is actually the home page of the website. May i know what causes those delay? Magento is a very CPU intense monster, is it due to the fact that its waiting for the server to respond due to lack of cpu power?

I did load test on different website before to study how server works, as i'm new to server hosting and optimizing. I personally use amazon and i understand amazon has their limit, i tested my server stress test and it would react in 0.5 seconds with 30 concurrent users, Micro instance, apache, varnish , compressed js and img, images from S3(CDN) and the load time only shoots up from 0.5 seconds to 1min ! at 31st concurrent user. Why does the shoot happens? It feels like it cannot take users when its stressed.

Where as the other site that i tested , the image above is one example , no matter how stress it is , from 20-50+ users, its load time is 1min(from overseas connection) locally i tested its 30 seconds.

I did check on other website too, some are hosted on share hosting, and they are able to take stress and function when its overloaded. It just react in 1min, for my case, amazon, it can even hit 3-4 mins when its stressed.

May i know how do i have this "Maxinum load time no matter how stress it is, not NO Matter but to a larger extend" What should i be looking at. *PS if i increase my Micro instance to Small instance, it can take only an additional 10 concurrent users, which isnt a big difference but when it come to cost, its a hell lots of a difference.

Any other knowledge would be totally appreciative, i'm here to learn and to help in future. Thank you for this platform.

Regards, Jonathan

Answer 1

This is the Time to First Byte and is determined by how long it takes the application to return any information. You would need to provide more information on the system you are using for specifics but I would look first at the application setup rather than the hosting for optimisation.

For example Magento can be a very "heavy" application without some form of caching in place. The time it takes to load all pages and execute related queries can result in a very high Time to First Byte Response. Similarly a very complex Wordpress installation can take some time to execute and return the first page byte.

Look for efficiencies and optimisations in the code if that is possible and also investigate an appropriate caching solution for your application.

One useful test is to upload a very simple HTML file and to check the Time to First Byte in serving this.

Answer 2

That long initial wait is probably while the server queries a database and prepares its response. The page being requested is, thus, dynamically created for each request.

The subsequent requests are for static JavaScript and CSS files. The response comes much more quickly since all the webserver has to do is look up those files and send them on over. No processing is required. And since those files are probably requested often, they are most likely already in the servers cache making the response time even faster.

You simply can't compare the two in terms of response time. Static content requires nothing but bandwidth and possibly a disk look up. Dynamic content may require expensive database queries and complex calculations as well.

Answer 3

The problem is that you're using a t1.Micro instance. These instances are not designed for much load. They're built for short bursts but normally inactive instances. To give you an idea, these servers have 2 ECU of burst power. If that burst is sustained for lets say 1 minute then your servers resources get throttled and you get basically no CPU usage. I recommend not using these servers for anything other than prototyping ideas. For more information about micro instances see this this article by amazon.

The performance of a small instance only has 1 ECU of power which is why you see only a slight difference in the number of users you can handle. I'll be honest though it sounds like you should spend some more time trying to improve the performance of your application instead of just putting it on a more powerful server. Amazon is not limited as far as computing power, but sometimes it is more expensive if all you want to do is host a simple webserver.