Applications should avoid creating many connection pools as doing so
    prevents connection reuse. Each connection pool holds its own set of
    connections alive so applications that have many pools also risk exhausting
    memory!

    The best practice in OkHttp 3 is to create a single OkHttpClient instance

    /**
     * Sets the interval between HTTP/2 and web socket pings initiated by this client. Use this to
     * automatically send ping frames until either the connection fails or it is closed. This keeps
     * the connection alive and may detect connectivity failures.
     *
     * If the server does not respond to each ping with a pong within `interval`, this client will