So nice to start discussing cool things in this even cooler forum :)
I am having a problem .. which i believe is already solved but i would love someone confirming actual experience with the same topic.
We are building a client / server architecture, consisting of a web server part and many clients.
Transport will be provided as either XML-RPC / SOAP / JSON or all at once.
All of the communication has to be encrypted and passed within SSL3.
We expect a high load when the application starts (> 2000 concurrent requests).
Combine this with xml parsing for the rpc api, things really look ugly :)
So it's a big mess :)
It will not be that much database bound behind the api - mostly files will be transferred from the server to the clients and simple api for control.
So it's pretty much a matter of 'what-to-do-with-ssl'.
I was thinking of hardware - NetApp or a similar application accelerator.
Can anyone give examples of a hardware piece that combines: Load balancer / SSL accelerator?
I have also been reading about open source software Load Balancers but i really doubt it would meet the needs. Anyone having the same experience (or had) ? :)
Performance is critical to the success of any web site, and yet today's web applications push browsers to their limits with increasing amounts of rich content and heavy use of Ajax. In his new book Even Faster Web Sites: Performance Best Practices for Web Developers, Steve Souders, web performance evangelist at Google and former Chief Performance Yahoo!, provides valuable techniques to help you optimize your site's performance.
Souders' previous book, the bestselling High Performance Web Sites, shocked the web development world by revealing that 80% of the time it takes for a web page to load is on the client side. In Even Faster Web Sites, Souders and eight expert contributors provide best practices and pragmatic advice for improving your site's performance in three critical categories:
- Network - Learn to share resources across multiple domains, reduce image size without loss of quality, and use chunked encoding to render pages faster.
- Browser - Discover alternatives to iframes, how to simplify CSS selectors, and other techniques.
Speed is essential for today's rich media web sites and Web 2.0 applications. With this book, you'll learn how to shave precious seconds off your sites' load times and make them respond even faster.
About the Author
Steve Souders works at Google on web performance and open source initiatives. His book High Performance Web Sites explains his best practices for performance along with the research and real-world results behind them. Steve is the creator of YSlow, the performance analysis extension to Firebug. He is also co-chair of Velocity 2008, the first web performance conference sponsored by O'Reilly. He frequently speaks at such conferences as OSCON, Rich Web Experience, Web 2.0 Expo, and The Ajax Experience.
Steve previously worked at Yahoo! as the Chief Performance Yahoo!, where he blogged about web performance on Yahoo! Developer Network. He was named a Yahoo! Superstar. Steve worked on many of the platforms and products within the company, including running the development team for My Yahoo!.
This post include detailed on who is using the platform and how from Enterprise applicaitons, to ISV that are looking for SaaS enablement, through partners and solution providers that are looking for to gain a competitive advantage and deploy application in short time to market and small initial investment.
Update: Here's the first result. Good response time until 400 users. At 1,340 users the response time was 6 seconds. And at 2000 users the site was effectively did. An interesting point was that errors that could harm a site's reputation started at 1000 users. Cheers to the company that had the guts to give this a try.
That which doesn't kill your site makes it stronger. Or at least that's the capacity planning strategy John Allspaw recommends (not really, but I'm trying to make a point here) in The Art of Capacity Planning:
Using production traffic to define your resources ceilings in a controlled setting allows you to see firsthand what would happen when you run out of capacity in a particular resource. Of course I'm not suggesting that you run your site into the ground, but better to know what your real (not simulated) loads are while you're watching, than find out the hard way. In addition, a lot of unexpected systemic things can happen when load increases in a particular cluster or resource, and playing "find the butterfly effect" is a worthwhile exercise.
The problem is how do you ever test to such a scale? That's where Randy Hayes of CapCal--a distributed performance testing system--comes in. Randy first contacted me asking for volunteers to try a test of a million users, which sounded like a great High Scalability sort of thing to do. Unfortunately he already found a volunteer so the idea now is to test how many users it takes to find a weakness in your site.
If anyone wants test their system to the breaking point the process goes like this:
In the past test generators were fun to write, but it was always difficult to get enough boxes to generate sufficient load. Maybe you remember installing test agents on people's work computers in cubeland so tests could be run over night when everyone was sleeping?
The cloud has changed all that. Testing-as-a-Service is one very obvious and solid use of the cloud. You need load? We got your load right here. Spin up more machines and you can drive your site into oblivion, but not in a denial-of-service attack sort of way :-)
Randy has a nice write up how their system works in CapCal Architecture and Background. It's similar in concept to other distributed testing frameworks you may have used, only this one operates in AWS and not on your own servers.
Not everyone is Google or Yahoo with zillions of users to test their software against. If you are interested in testing your site please contact Randy and give it a go. And when you are done it would be fun to have an experience report here about what you learned and what changes you needed to make.
HotPads abandoned our managed hosting in December and took the leap over to EC2 and its siblings. The presentation has a lot of detail on costs and other things to watch out for, so if you're currently planning your "cloud" architecture, you'll find some of this really helpful.
A short summary of differences between Oracle Coherence and GigaSpaces XAP.
I need some help in making site access fast. On an average my site has the traffic 2500 hits per day and on 16th May it had 60,000 hits. On this day site was loading very slow even it was getting time out. I also check out the processes running by using "top" command it was indicating mysql was taking too much load.
There are around 166 tables (Including PHPBB forum) in my database. All contents on site are displayed by fetching it from database. I have also added indexing to respective tables where it is required. Plain PHP/HTML coding is used.
PHP -- 5.2
MYSQL -- 5.0
Apache -- 2.0
Following is all the server details of my site:
CPU : Single Socket Dual Core AMD Opteron 1212HE
Memory: 2GB DDR RAM
Hard Drive: 250GB SATA
Ethernet: 100Mb Primary Ethernet Card
(/var/log) # uname -a
Linux 2.6.9-67.0.15.ELsmp #1 SMP Tue Apr 22 13:50:33 EDT 2008 i686 athlon i386 GNU/Linux
(/var/log) # free -m
total used free shared buffers cached
Mem: 2026 1976 49 0 143 1474
-/+ buffers/cache: 359 1667
Swap: 1027 0 1027
RAM: 2 G
(/var/log) # df -h
Filesystem Size Used Avail Use% Mounted on
/dev/sda5 227G 20G 196G 10% /
/dev/sda1 99M 12M 82M 13% /boot
none 1014M 0 1014M 0% /dev/shm
/dev/sda2 2.0G 196M 1.7G 11% /tmp
Disk usage: 10% used/ 196 G available.
Its an dedicated server and only 1 website is hosted.
Can anybody please suggest how can I optimize site in more appropriate manner so that it will not go down if traffic increases on site.
Multicore computers shift the burden of software performance from chip designers and architects to software developers.
What is the parallel Computing ? and what the different between Multi-Threading and Concurrency and Parallelism ? and what is differences between task and data parallel ? and how we can use it ?
Fundamental article into Parallel Programming...
Update:: Eucalyptus Goes Commercial with $5.5M Funding Round. This removes my objection that it's an academic project only. Go team go!
Rich Wolski, professor of Computer Science at the University of California, Santa Barbara, gave a spirited talk on Eucalyptus to a large group of very interested cloudsters at the Eucalyptus Cloud Meetup. If Rich could teach computer science at every school the state of the computer science industry would be stratospheric. Rich is dynamic, smart, passionate, and visionary. It's that vision that prompted him to create Eucalyptus in the first place. Rich and his group are experts in grid and distributed computing, having a long and glorious history in that space. When he saw cloud computing on the rise he decided the best way to explore it was to implement what everyone accepted as a real cloud, Amazon's API. In a remarkably short time they implement Eucalyptus and have been improving it and tracking Amazon's changes ever since.
The question I had going into the meetup was: should Eucalyptus be used to make an organization's private cloud? The short answer is no. Wait wait, it's now yes, see the update at the beginning of the article.
The project is of high quality, the people are of the highest quality, but in the end Eucalyptus is a research project from a university. As an academic project Eucalyptus is subject to changes in funding and the research interests of the team. When funding sources dry up so does the project. If the team finds another research area more interesting, or if they get tired of chasing a continuous stream of new Amazon features, or no new grad students sign on, which will happen in a few years, then the project goes dark.
Fears over continuity have at least two solutions: community support and commercial support. Eucalyptus could become community supported open source project. This is unlikely to happen though as it conflicts with the research intent of Eucalyptus. The Eucalyptus team plans to control the core for research purposes and encourage external development of add-on service like SQS. Eucalyptus won't go commercial as University projects must stay clear from commercial pretensions. Amazon is "no comment" on Eucalyptus so it's not clear what they would think of commercial development should it occur.
Taken together these concerns imply Eucalyptus is not a good base for an enterprise quality private cloud. Which they readily admit. It's not enterprise ready Rich repeats. It's not that the quality isn't there. It is and will be. And some will certainly base their private cloud on Eucalyptus, but when making a decision of this type you have to be sure your cloud infrastructure will be around for the long haul. With Eucalyptus that is not necessarily the case. Eucalyptus is still a good choice for it's original research purpose, or as cheap staging platform for Amazon, or as base for temporary clouds, but as your rock solid private cloud infrastructure of the future Eucalyptus isn't the answer.
The long answer is a little more nuanced and interesting.
The primary purpose for Eucalyptus is research. It was never meant to be our little untethered private Amazon cloud. But if it works, why not?
Eucalyptus is Not a Full Implementation of the Amazon Stack
Eucalyptus implements most of EC2 and a little of S3. They hope to get community support for the rest. That of course makes Eucalyptus far less interesting as a development platform. But if your use for Eucalyptus is as an instant provisioning framework you are still in the game. Their emulation of EC2 is so good RightScale was able to operate on top of Eucalyptus. Impressive.
But even in the EC2 arena I have to wonder for how long they'll track Amazon development. If you are a researcher implementing every new Amazon feature is going to get mighty old after a while. It will be time to move on and if you are dependent on Eucalyptus you are in trouble. Sure, you can move to Amazon but what about that $1 million data center buildout?
Developing software not tied to the Amazon service stack then Eucalyptus would work great.
As an Amazon developer I would want my code to work without too much trouble in both environments. Certainly you can mock the different services for testing or create a service layer to hide different implementations, but that's not ideal and makes Eucalyptus as an Amazon proxy less attractive.
One of the uses for Eucalyptus is to make Amazon cheaper and easier by testing code locally without out having to deploy into Amazon all the time. Given the size of images the bandwidth and storage costs add up after a while, so this could make Eucalyptus a valuable part of the development process.
Eucalyptus is Not as Scalable as Amazon
No kidding. Amazon has an army of sysadmins, network engineers, and programmers to make their system work at such ginormous scales. Eucalyptus was built on smarts, grit and pizza. It will never scale as well as Amazon, but Eucalyptus is scalable to 256 nodes right now. Which is not bad.
Rich thinks with some work they already know about it could scale to 5000 nodes. Not exactly Amazon scale, but good enough for many data center dreams.
One big limit Eucalyptus has is the self-imposed requirement to work well in any environment. It's just a tarball you can install on top of any network. They rightly felt this was necessary for adoption. Saying to potential customers that you need to setup a special network before you can test this software tends to slow down adoption. By making Eucalyptus work as an overlay they soothed a lot of early adopter pain.
But by giving up control of the machines, the OS, the disk, and the network they limited how scalable they can be. There's more to scalability than just software. Amazon has total control and that gives them power. Eucalyptus plans to make more invasive and more scalable options available in the future.
Lacks Some Private Cloud Features
Organizations interested in a private cloud are often interested in:
Eucalyptus satisfies many of these needs, but a couple are left wanting:
These features may or may not be important to you.
Clouds vs GridsEndless pixels have been killed defining clouds, grids, and how they are different enough that there's really a whole new market to sell into. Rich actually makes a convincing argument that grids and clouds are different and do require a completely different infrastructure. The differences:
Combining GPU power with PostgreSQL
PostgreSQL is one of the world's leading Open Source databases and it provides enormous flexibility as well as extensibility. One of the key features of PostgreSQL is that users can define their own procedures and functions in basically any known programming language. With the means of functions it is possible to write basically any server side codes easily.
Now, all this extensibility is basically not new. What does it all have to do with scaling and then? Well, imagine a world where the data in your database and enormous computing power are tightly integrated. Imagine a world where data inside your database has direct access to hundreds of FPUs. Welcome to the world of CUDA, NVIDIA's way of making the power of graphics cards available to normal, high-performance applications.
When it comes to complex computations databases might very well turn out to be a bottleneck. Depending on your application it might easily happen that adding more CPU power does not improve the overall performance of your system – the reason for that is simply that bringing data from your database to those units which actually do the computations is ways too slow (maybe because of remote calls and so on). Especially when data is flowing over a network, copying a lot of data might be limited by network latency or simply bandwidth. What if this bottleneck could be avoided?
CUDA is C / C++
Basically a CUDA program is simple a C program with some small extensions. The CUDA subsystem transforms your CUDA program to normal C code which can then be compiled and linked nicely with existing code. This also means that CUDA code can basically be used to work inside a PostgreSQL stored procedure easily. The advantages of this mechanism are obvious:
GPUs can do matrix and FPU related operations hundreds of times faster than any CPU
the GPU is used inside the database and thus no data has to be transported over slow lines
basically any NVIDIA graphics card can be used
you get enormous computing power for virtually zero cost
you can even build functional indexes on top of CUDA stored procedures
not so many boxes are needed because one box is ways faster
How to make it work?
How to make this all work now? The goal for this simplistic example is to generate a set of random number on the CPU, copy it to the GPU and make the code callable from PostgreSQL.
Here is the function to generate random numbers and to copy them to the GPU:
/* implement random generator and copy to CUDA */
/* allocate host memory and CUDA memory */
nn_precision *host_p = (nn_precision *)pg_palloc(sizeof(nn_precision) * number_of_values);
CUDATOOLS_SAFE_CALL( cudaMalloc( (void**) &cuda_float_p,
sizeof(nn_precision) * number_of_values));
/* create random numbers */
for (int i = 0; i < number_of_values; i++)
host_p[i] = (nn_precision) drand48();
/* copy data to CUDA and return pointer to CUDA structure */
CUDATOOLS_SAFE_CALL( cudaMemcpy(cuda_float_p, host_p,
sizeof(nn_precision) * number_of_values, cudaMemcpyHostToDevice) );
Now we can go and call this function from a PostgreSQL stored procedure:
/* import postgres internal stuff */
/* prototypes to silence compiler */
extern Datum test_random(PG_FUNCTION_ARGS);
/* define function to allocate N random values (0 - 1.0) and put it into the CUDA device */
int number = PG_GETARG_INT32(0);
nn_precision *p = generate_random_numbers(number);
This code then now be nicely compiled just like any other PostgreSQL C extension. The test random function can be called just like this:
Of course this is a just brief introduction to see how things can practically be done. A more realistic application will need more thinking and can be integrated into the database even more closely.
Professional CUDA programming
Professional PostgreSQL services
The official PostgreSQL Website
The official CUDA site