首次分析
我们现在准备好分析其中一个示例应用了。第一个示例，我们使用 slow-event-loop。首先，我们通过在 examples 目录中运行 node slow-event-loop 来确认它已准备好并能工作。进程开始运行后，我们就可以在浏览器中访问 http://localhost:3000/ 进行检查。
We're now ready to profile one of the example applications. For the first example, we will use slow-event-loop. First, let's confirm that it is ready and working by running node slow-event-loop from inside the examples directory. Once the process seems to be running we can visit http://localhost:3000/ in a browser to check.
我们可以在浏览器中看到一些基本输出，比如 {}。在命令行中按 Ctrl-C 关闭 slow-event-loop 服务器。
We should see some basic output in the browser, like {}. Ctrl-C in the command line to close the slow-event-loop server.
因为这是一个服务器，所以我们需要进行负载测试。对只处理一个请求的服务器进行分析不会为我们提供太多信息，也不知道它在处理许多请求时会如何执行。我们建议使用基准测试工具 autocannon。
This is a server, so we need to apply load. Profiling a server handling just one request doesn't give us much data or indication of how it performs when handling many requests. We recommend the benchmarking tool Autocannon.
当执行 clinic 时，我们也会在示例应用目录中执行 autocannon，所以我们先使用以下命令全局安装它：
We will execute autocannon in the example application directories when we call the clinic executable, so let's install it globally, with the following command:
npm install -g autocannon
要对服务器进行负载测试，我们需要使用 Doctor 运行它，并在它开始侦听端口时立即调用 autocannon。只要服务器准备好处理请求并且 Doctor 也准备好收集数据，就会使用大量请求轰炸服务器。
To load-test the server, we want to run it with Doctor, and point autocannon at it as soon as it starts listening on a port. This will bombard the server with requests, as soon as it is ready to handle them and Doctor is ready to collect data.
我们用下面这个命令完成所有操作，它会自动分配正确的端口：
Let's do all that with this single command, which automatically assigns the correct ports:
clinic doctor --on-port 'autocannon localhost:$PORT' -- node slow-event-loop
我们拆分一下这个命令：
Let's break this command down:
clinic doctor调用 Doctor 命令行工具。
The clinic doctor portion invokes the Doctor command tool.
- --on-port 参数指定在服务开始监听端口后马上执行的脚本，即
autocannon localhost:$PORT。
The --on-port flag will execute the supplied script as soon as the server starts listening on a port.
- 脚本中的
$PORT变量是服务器开始侦听的第一个端口。
The $PORT variable in that script is set to the first port that the server began listening on.
--后面的命令用于启动我们要分析的服务，比如这里的node slow-event-loop。
Everything after the double-dash (--) is the command which starts the server that we want to profile, in this case node slow-event-loop.
这行命令会运行三个可执行文件：父可执行文件 clinic flame, --on-port 中的可执行文件 autocannon，以及可执行文件 Node。
This one command runs three executables: the clinic doctor parent executable, the autocannon executable in --on-port and the node executable.
运行该命令后，slow-event-loop 服务器将被 10 个并发连接的请求命中 10 秒（autocannon 的默认值）。然后将结果编译成单个 HTML 文件，该文件会浏览器中自动打开。
Upon running the command, the slow-event-loop server will be hit by requests from 10 concurrent connections for 10 seconds (as per autocannon defaults). then the results be compiled into a single HTML file that should automatically open in the browser.
生成的 HTML 类似于下面这样：
The resulting HTML should look similar to the following:
