tip 3 done

sources/tech/20151028 10 Tips for 10x Application Performance.md

@@ -97,16 +97,22 @@ There are three main techniques for caching content generated by web application
 - **从过载服务器拿走数据**。机器经常因为要完成某些其它的任务而造成某个任务的执行速度比测试结果要差。将数据缓存在不同的机器上可以提高缓存资源和非缓存资源的效率，而这知识因为主机没有被过度使用。
 
 Caching for web applications can be implemented from the inside – the web application server – out. First, caching is used for dynamic content, to reduce the load on application servers. Then, caching is used for static content (including temporary copies of what would otherwise be dynamic content), further off-loading application servers. And caching is then moved off of application servers and onto machines that are faster and/or closer to the user, unburdening the application servers, and reducing retrieval and transmission times.
+对web 应用的缓存机制可以web 应用服务器内部实现。第一，缓存动态内容是用来减少应用服务器加载动态内容的时间。然后，缓存静态内容（包括动态内容的临时拷贝）是为了更进一步的分担应用服务器的负载。而且缓存之后会从应用服务器转移到对用户而言更快、更近的机器，从而减少应用服务器的压力，减少提取数据和传输数据的时间。
 
 Improved caching can speed up applications tremendously. For many web pages, static data, such as large image files, makes up more than half the content. It might take several seconds to retrieve and transmit such data without caching, but only fractions of a second if the data is cached locally.
+改进过的缓存方案可以极大的提高应用的速度。对于大多数网页来说，静态数据，比如大图像文件，构成了超过一半的内容。如果没有缓存，那么这可能会花费几秒的时间来提取和传输这类数据，但是采用了缓存之后不到1秒就可以完成。
 
 As an example of how caching is used in practice, NGINX and NGINX Plus use two directives to [set up caching][16]: proxy_cache_path and proxy_cache. You specify the cache location and size, the maximum time files are kept in the cache, and other parameters. Using a third (and quite popular) directive, proxy_cache_use_stale, you can even direct the cache to supply stale content when the server that supplies fresh content is busy or down, giving the client something rather than nothing. From the user’s perspective, this may strongly improves your site or application’s uptime.
+举一个在实际中缓存是如何使用的例子， NGINX 和NGINX Plus使用了两条指令来[设置缓存机制][16]：proxy_cache_path 和 proxy_cache。你可以指定缓存的位置和大小，文件在缓存中保存的最长时间和其他一些参数。使用第三条（而且是相当受欢迎的一条）指令，proxy_cache_use_stale，如果服务器提供新鲜内容是忙或者挂掉之类的信息，你甚至可以让缓存提供旧的内容，这样客户端就不会一无所得。从用户的角度来看这可以很好的提高你的网站或者应用的上线时间。
 
 NGINX Plus has [advanced caching features][17], including support for [cache purging][18] and visualization of cache status on a [dashboard][19] for live activity monitoring.
+NGINX plus 拥有[高级缓存特性][17]，包括对[缓存清除][18]的支持和在[仪表盘][19]上显示缓存状态信息。
 
 For more information on caching with NGINX, see the [reference documentation][20] and [NGINX Content Caching][21] in the NGINX Plus Admin Guide.
+要想获得更多关于NGINX 的缓存机制的信息可以浏览NGINX Plus 管理员指南中的 [reference documentation][20] 和 [NGINX Content Caching][21] 。
 
-**Note**: Caching crosses organizational lines between people who develop applications, people who make capital investment decisions, and people who run networks in real time. Sophisticated caching strategies, like those alluded to here, are a good example of the value of a [DevOps perspective][22], in which application developer, architectural, and operations perspectives are merged to help meet goals for site functionality, response time, security, and business results, )such as completed transactions or sales.
+**Note**: Caching crosses  lines between people who develop applications, people who make capital investment decisions, and people who run networks in real time. Sophisticated caching strategies, like those alluded to here, are a good example of the value of a [DevOps perspective][22], in which application developer, architectural, and operations perspectives are merged to help meet goals for site functionality, response time, security, and business results, such as completed transactions or sales.
+**注意**：缓存机制分布于应用开发者、投资决策者以及实际的系统运维人员之间。本文提到的一些复杂的缓存机制从[DevOps 的角度][22]来看很具有价值，即对集应用开发者、架构师以及运维操作人员的功能为一体的工程师来说可以满足他们对站点功能性、响应时间、安全性和商业结果，如完成的交易数。
 
 ### Tip #4: 压缩数据 ###
 
@@ -310,4 +316,3 @@ via: https://www.nginx.com/blog/10-tips-for-10x-application-performance/?hmsr=to
 [51]:http://blog.loadimpact.com/blog/how-bad-performance-impacts-ecommerce-sales-part-i/
 [52]:https://blog.kissmetrics.com/loading-time/?wide=1
 [53]:https://econsultancy.com/blog/10936-site-speed-case-studies-tips-and-tools-for-improving-your-conversion-rate/
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