Metrics
度量指标
There are four key performance metrics that most of you are interested in as you develop your XML-based Web application:
当开发基于XML的Web应用程序时，大部分人对以下四个主要的性能度量指标感兴趣：
· Working set: The peak amount of memory used by MSXML to process requests. Once the working set exceeds available RAM, performance usually declines sharply as the operating system starts paging memory out to disk.
· 工作集（Work set）：MSXML处理请求的峰值内存空间。一旦处理空间超过了可用的RAM，操作系统将页面调度到磁盘，性能通常会急剧下降。
· Megabytes per second: Simply a measure of raw speed for a given operation, such as the document load method. By itself it is interesting, but to get the real picture for a production application, you really need to consider the next two metrics as well.
· 百兆字节每秒：简单衡量一给定的操作（如文件load方法）的速度。但是在实际应用中，你还需要考虑以下两个衡量标准。
· Requests per second: A measure of how many requests the XML parser can handle per second. An XML parser might have a high megabytes-per-second rate, but if it is expensive to set up and tear down that parser, it will still have a low throughput in requests per second. This metric can help you calculate how many clients your server can handle under a peak load. Obviously, this depends on how heavily the clients are going to load up your server. For example, if the clients hit the server at a peak rate of one request per second, and if the server can do 150 requests per second, the server can probably handle up to 150 clients.
· 每秒处理的请求数：用来表示XML解析器每秒可处理的请求数。一个XML解析器可能每秒处理的百兆字节量很高，但是如果初始化和关闭该解析器的代价很大，那么它的每秒处理请求数仍旧很低。这个度量指标可以帮助你计算在峰值负载下，服务器能够接受多少客户。显然，这取决于客户端访问服务器的频率。例如，如果每个客户端点击服务器的峰值是每秒一个请求，而服务器能够在一秒钟内处理150个请求，那么服务器就能够同时处理150个客户。
· Scaling: A measure of how well your server can process requests in parallel. If your server is processing 150 client requests in parallel, then it is doing a lot of multi-threading. Processing 150 threads in parallel is rather much for one processor, which will spend a lot of time just switching between these threads. In this scenario, you might add more processors to the computer to share the load. 共2页 第1页 第2页
