https.globalAgent
全局 https.Agent 实例,用于所有 HTTPS 客户端请求。与默认 https.Agent 配置不同的是,它启用了 keepAlive 并将 timeout 设置为 5 秒。
【Global instance of https.Agent for all HTTPS client requests. Diverges
from a default https.Agent configuration by having keepAlive enabled and
a timeout of 5 seconds.】