Google offers tips on reducing latency on large scale systems
In the latest ACM magazine, Google fellows offer a few secrets to keeping Web systems responding to users as quickly as possible
IDG News Service - Running the world's most popular website, Google engineers know a thing or two about keeping a site responsive under very high demand. In the latest issue of the ACM (Association for Computer Machinery) monthly magazine, Google reveals a few secrets to maintaining speedy operations on large-scale systems.
Systems as large as Google's can suffer from even a few sluggish individual nodes, write the article's authors, Jeffrey Dean, a Google fellow in the company's systems infrastructure group, and Luiz AndrA(c) Barroso, a Google fellow who is technical lead of Google's core computing infrastructure. The good news is that while slow nodes can never be eliminated entirely, a system can be designed to still offer speedy service to the user, the authors wrote.
"It's an important topic. When you have a [user] request that needs to gather information from many machines, inherently some of the machines will be slow," said Ion Stoica, an ACM reviewer who is a computer science professor at the University of California Berkeley, as well a co-founder of video stream optimization software provider Conviva.
"As [Internet services] try to reduce the response times more and more, the problem will become more difficult because [the systems] will have less time to decide what to do when something goes wrong. So it will be an area of research and development that will get attention over the next few years," he said.
Looking at performance variability is particularly important with large distribution systems such as Google's, because performance troubles on even a single node can result in delays that affect many users. "Variability in the latency distribution of individual components is magnified at the service level," the authors wrote.
For instance, consider a server that typically responds to a request within 10 milliseconds but takes an entire second to fulfill a request every 100th time. In a single server environment, this means that only every 100th user would get a slow response. But if each user request is handled by 100 servers -- each with the same latency characteristics -- then 63 out of every 100 users would get a slow response, the authors calculated.
Performance variability can take place for a number of reasons, the authors note. Sharing resources, such as running multiple application on a single server, can affect the response time of each application. The length of a component's work queue may also have a factor, as would routine maintenance jobs that can take up resources.
The Google engineers offered a number of techniques for mitigating slow performance from individual nodes, such as breaking jobs into smaller components and better managing routine maintenance tasks.
- 15 Non-Certified IT Skills Growing in Demand
- How 19 Tech Titans Target Healthcare
- Twitter Suffering From Growing Pains (and Facebook Comparisons)
- Agile Comes to Data Integration
- Slideshow: 7 security mistakes people make with their mobile device
- iOS vs. Android: Which is more secure?
- 11 sure signs you've been hacked
- 4 Customers who never have to refresh their PCs again This paper illustrates a common theme: the combination of desktop virtualization and thin client computing helps organizations deliver an up-to-date user experience more...
- Mobile Devices: The New Thin Clients Get essential guidance for understanding the role thin clients plus virtual desktops play in the enterprise today.
- Taking Windows Mobile on Any Device Taking Windows applications mobile has many advantages, but the process of identifying a solution is complex. Learn how to solve this complex problem...
- PaaS - Powering a New Era of Business IT Why PaaS has suddenly become relevant and irresistible to many organizations. Dive into the opportunities and considerations associated with using PaaS from an...
- Redefine Your IT Operations: Remote Office IT Has Never Been Simpler Join us to see why PC Pro named Dell PowerEdge VRTX the "2013 Server of the Year." PowerEdge VRTX may be just what...
- Mobile Apps and Devices Slash Customer Cycle Time Consolidated Engineering Laboratories' field employees used to collect data on triplicate forms that were sometimes hard to read and difficult to manage. After... All Hardware White Papers | Webcasts