新增于: v14.5.0, v12.19.0
默认设置为 Infinity。
确定代理可以打开多少个并发套接字。
与 maxSockets 不同，此参数适用于所有来源。
Added in: v14.5.0, v12.19.0
By default set to Infinity. Determines how many concurrent sockets the agent
can have open. Unlike maxSockets, this parameter applies across all origins.