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#SFMySQL Meetup Message Board › I want to discuss how to solve MYSQL performance problems using the Use Case

I want to discuss how to solve MYSQL performance problems using the Use Case of Second Life @ tonights meeting?

A. Karriem A.
ak2webd3
Oakland, CA
Post #: 6
I want to discuss how to solve MYSQL performance problems using the Use Case of Second Life @ tonights meeting. The link describing their architecture is here http://blogs.computer...­
A. Karriem A.
ak2webd3
Oakland, CA
Post #: 7
I want to discuss how to solve MYSQL performance problems using the Use Case of Second Life @ tonights meeting. The link describing their architecture is here http://blogs.computer...­

I chose this use case because it includes opensource of the production code & real world #'s on their server farm in the above link!

http://www.informatio...­
Linden Lab opened the source code to its client software, which runs on Windows, Mac OS X, and Linux, in January, and the company is using that project as an opportunity to learn about governance of open source projects, says Ondrejka.

The servers support 34 terabytes of user-created content, and the traffic load for accessing that content is very different than a conventional Web site. "If you think of a Web site like Digg, there are relatively few creators of information, and lots and lots of consumers of information. In Second Life, the equation is different, in that two-thirds of the users are actively creating content over time."

To help manage growth, Linden Lab is looking for IT staff who have done it before. "We're looking for an operations-specific person who was involved in scaling a server farm from where we are today, which is 2,000 boxes, to 10,000 boxes. There are very few people in the industry who have done that," Miller said.

Linden Lab went live with its Dallas co-location facility in December. "We're consuming a lot of floor space. It makes sense to have it geographically distributed. It creates redundancy and backup. If we lose bandwidth at one facility, we can shift load and resources to another location," Miller says.

Since then, residents have expressed concerns that the split locations have contributed to performance slowdowns -- which the residents call "lagginess."

To maintain the illusion that Second Life is a virtual world, avatars and their associated attachments and processes need to be able to transition from one sim to another seamlessly. Avatars near the edge of one sim need to be able to look over and see activity in the next sim, just like people in the real world can see activity going on in the next lot of land. All of this needs to happen even if the sims are located on different servers -- even if the handoff between sims must bridge 1,700 miles between Dallas and San Francisco.

However, Linden Lab has designed the network so that the handoff between co-location facilities doesn't result in increased lag, Miller said. One method is to cluster the sims so that regions that are in proximity to each other in Second Life are running on servers in the same real-world location.

"If a Texas-based simulator needs data from a database in San Francisco, it gets it, and it doesn't block action on the part of the user," Miller says.

To help make the user experience more pleasant, Linden Lab is looking to improve performance of the scripting language used in Second Life. The language is called LSL, for Linden Scripting Language. The language is similar to C.

Objects in Second Life are built using a combination of primitive shapes, or "prims," which are sized, scaled, and stretched as needed, with images, called "textures," applied to the surface of the prim to alter its appearance. For example, on the exterior wall of a virtual skyscraper, textures would be use to provided the appearance of bricks, windows, and other features.

LSL determines how the objects behave, controlling the waving of virtual hair, driving a virtual boat or automobile, or behavior of a virtual gun. Everything in Second Life is composed of some combination of prims, textures, and LSL scripts.

In an August video, Ondrejka described how he wrote LSL. "It got written in a week, like all scripting languages," Ondrejka said. He decided he needed to roll his own scripting language for Second Life after he determined that he knew more about writing a scripting language than he did about modifying another language, like Java, to meet Second Life's requirements.

Performance is slow, at only 150 million instructions per second, with inconsistent syntax and limited support outside of Second Life. "Nobody's using LSL to do real-world things," he said.

To improve performance, Linden Lab is porting LSL to Mono, the open source implementation of Microsoft.Net. In tests, the Mono implementation of LSL runs 1,000 times faster than Linden Lab's current version.

Linden Lab plans to begin testing the Mono implementation in the second quarter. Later, Second Life's transition to Mono will enable the software to support scripting in other Mono-compliant languages, such as Visual Basic and C#.
A. Karriem A.
ak2webd3
Oakland, CA
Post #: 8
The link describing their architecture is here in Debian Linux and the MySQL database here
http://www.informatio...­
Life struggles with its explosive growth and new popularity, the developer, Linden Lab, is redesigning the service to handle hundreds of times as much traffic as it's dealing with today.

Second Life is seeing 20% monthly growth in the number of concurrent users, going from a then-record 18,000 users logged in at once in December to a record 36,000 on Sunday. The maximum capacity of the current network is 100,000 simultaneous users, says Joe Miller, VP of platform and technology development for Linden Lab.

Rapid growth has led to problems for Second Life users, who often complain about slow response times during peak periods. Users also see problems with screen graphics, moving around between regions of the virtual world, and discrepancies in transactions involving the in-world currency, called "Linden Dollars." Search results are becoming out of date quickly.

To help deal with current and future growth, Linden Lab is looking to redesign the network. Linden Lab is looking to increase capacity from 100,000 simultaneous sessions to tens of millions of simultaneous logins. Linden Lab also needs to manage that upgrade without interrupting service to existing users.

"We're swapping engines out at 40,000 feet while still flying," Miller says.

Second Life runs on 2,000 Intel and Advanced Micro Devices servers in two co-location facilities in San Francisco and Dallas. The company has a commitment to open source, with servers running Debian Linux and the MySQL database. Linden Lab chose Debian Linux because the software is suited to scaling massively with a small IT staff, say Linden Lab CTO Cory Ondrejka. MySQL allows the server farms to scale horizontally, by adding large numbers of low-power servers as needed, rather than vertically, which would have required Second Life to run on a few, powerful systems, Miller says.
A. Karriem A.
ak2webd3
Oakland, CA
Post #: 9
but they seem to be switching to an Open Source .net architecture for their next generation architecture

In an August video http://www.informatio...­


Ondrejka described how he wrote LSL. "It got written in a week, like all scripting languages," Ondrejka said. He decided he needed to roll his own scripting language for Second Life after he determined that he knew more about writing a scripting language than he did about modifying another language, like Java, to meet Second Life's requirements.

Performance is slow, at only 150 million instructions per second, with inconsistent syntax and limited support outside of Second Life. "Nobody's using LSL to do real-world things," he said.

To improve performance, Linden Lab is porting LSL to Mono, the open source implementation of Microsoft.Net. In tests, the Mono implementation of LSL runs 1,000 times faster than Linden Lab's current version.

Linden Lab plans to begin testing the Mono implementation in the second quarter. Later, Second Life's transition to Mono will enable the software to support scripting in other Mono-compliant languages, such as Visual Basic and C#.

As a stopgap measure to manage growth, Linden Lab said in mid-February that it might limit logins on the weekends. Linden Lab said it might lock out some free accounts during periods of peak traffic, limiting access to the network to premium accounts -- who pay $9.95 per month -- and free accounts that have bought or sold Linden Dollars through Linden Lab. The announcement proved controversial, with some residents saying it was a sign that Second Life is collapsing.

Another measure to manage growth is to move some of Second Life to the Web. To experience most of Second Life, users need to download and install a specialized client. But Second Life already allows users to manage parts of their Second Life experience from the Web. Users can create accounts, check whether their Second Life friends are online, and buy and sell land and Linden Dollars using a Web browser. Linden Lab is considering how it should expand the Web capabilities to reduce the burden on Second Life servers. This will involve creating open APIs to allow third-party developers to write their own applications.
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