new agent options

• options {Object} 要在代理上设置的可配置选项集。可以包含以下字段：
  • keepAlive {boolean} 即使没有未完成的请求，也要保持套接字，这样它们就可以被用于将来的请求而无需重新建立 TCP 连接。 不要与 Connection 请求头的 keep-alive 值混淆。 Connection: keep-alive 请求头始终在使用代理时发送，除非明确指定 Connection 请求头、或者 keepAlive 和 maxSockets 选项分别设置为 false 和 Infinity，在这种情况下将会使用 Connection: close。 默认值: false。
  • keepAliveMsecs {number} 当使用 keepAlive 选项时，指定用于 TCP Keep-Alive 数据包的[初始延迟][initial delay]。当 keepAlive 选项为 false 或 undefined 时则忽略。默认值: 1000。
  • maxSockets {number} 每个主机允许的套接字的最大数量。默认值: Infinity。
  • maxTotalSockets {number} Maximum number of sockets allowed for all hosts in total. Each request will use a new socket until the maximum is reached. Default: Infinity.
  • maxFreeSockets {number} 在空闲状态下保持打开的套接字的最大数量。仅当 keepAlive 被设置为 true 时才相关。默认值: 256。
  • scheduling {string} Scheduling strategy to apply when picking the next free socket to use. It can be 'fifo' or 'lifo'. The main difference between the two scheduling strategies is that 'lifo' selects the most recently used socket, while 'fifo' selects the least recently used socket. In case of a low rate of request per second, the 'lifo' scheduling will lower the risk of picking a socket that might have been closed by the server due to inactivity. In case of a high rate of request per second, the 'fifo' scheduling will maximize the number of open sockets, while the 'lifo' scheduling will keep it as low as possible. Default: 'fifo'.
  • timeout {number} 套接字的超时时间，以毫秒为单位。这会在套接字被连接之后设置超时时间。

[socket.connect()] 中的 options 也受支持。

被 [http.request()] 使用的默认的 [http.globalAgent] 具有所有这些值且被设置为各自的默认值。

要配置其中任何一个，则必须创建自定义的 [http.Agent] 实例。

const http = require('http');
const keepAliveAgent = new http.Agent({ keepAlive: true });
options.agent = keepAliveAgent;
http.request(options, onResponseCallback);