resources; too few harms latency.

For asynchronous calls, [`Dispatcher`](https://square.github.io/okhttp/4.x/okhttp/okhttp3/-dispatcher/) implements policy for maximum simultaneous requests. You can set maximums per-webserver (default is 5), and overall (default is 64)....

   * this address.
   *
   * If [planToReplace] is non-null, this will swap it for a pooled connection if that pooled
   * connection uses HTTP/2. That results in fewer sockets overall and thus fewer TCP slow starts.
   */
  internal fun planReusePooledConnection(
    planToReplace: ConnectPlan? = null,
    routes: List<Route>? = null,
  ): ReusePlan? {
    val result =

   * the problem impacts just one stream or the entire connection.
   *
   * To differentiate the two cases we ping the server when a stream times out. If the overall
   * connection is fine the ping will receive a pong; otherwise it won't.
   *
   * The deadline to respond to this ping attempts to limit the cost of being wrong. If it is too

     * this client silently recovers from the following problems:
     *
     * * **Unreachable IP addresses.** If the URL's host has multiple IP addresses,
     *   failure to reach any individual IP address doesn't fail the overall request. This can
     *   increase availability of multi-homed services.
     *
     * * **Stale pooled connections.** The [ConnectionPool] reuses sockets