Scalability/Scalability (scalable/scalability)

Original address: http://www.jdon.com/scalable.html

Scalability (scalability) is a software system computing processing capacity of the design indicators, high scalability represents a kind of elasticity, in the system expansion and growth process, the software can guarantee exuberant vitality, through the few changes or even just the acquisition of hardware equipment, can achieve the overall system processing capacity of linear growth, Achieve high throughput and low latency performance.

Scalability and pure performance tuning are fundamentally different, scalability is a combination of high performance, low cost and maintainability, and many other factors such as a comprehensive consideration and balance, scalability of the smooth linear performance improvement, more focused on the horizontal scaling of the system, through the low-cost server to achieve distributed computing While general performance optimization is only the performance index optimization of a single machine. All they have in common is a choice between throughput and latency based on the application's characteristics, and of course the cap theorem is constrained by the horizontal scaling partition.

The scalability of the software is very important, but it is difficult to grasp, the industry is trying to save the developer energy through cloud computing or high concurrency language, but no matter what technology, if the application system is monolithic, such as heavily dependent on the database, the system reached a certain level of access, The load is concentrated on one or two database servers, where partitioning scaling is difficult, as Hibernate framework creator Gavin King said: Relational databases are the least extensible.

Performance and Scalability

• What is a performance issue? If your system is slow for a user, it is performance issues;
• What are extensibility issues? If your system is fast for a user, it slows down as the user grows in high traffic.

Latency and throughput

Latency and throughput are a pair of metrics that measure scalability, and we want to get low latency and high throughput system architectures. The so-called low latency, that is, the user can feel the system response time, such as a Web page in a few seconds to open, the shorter the lower the delay, and the throughput indicates how many users can enjoy this low latency, if the concurrent user volume is very large, users feel that the Web page opened slowly, which means that the system architecture throughput needs to be improved

The goal of extensibility is to get the maximum throughput with acceptable latency. Reliability (availability) Goal: Get the consistency of data updates with an acceptable delay.

Scalability/Scalability (scalable/scalability)