# Class: BalancedPool
Extends: `undici.Dispatcher`
A pool of [Pool](Pool.md) instances connected to multiple upstreams.
Requests are not guaranteed to be dispatched in order of invocation.
## `new BalancedPool(upstreams [, options])`
Arguments:
* **upstreams** `URL | string | string[]` - It should only include the **protocol, hostname, and port**.
* **options** `BalancedPoolOptions` (optional)
### Parameter: `BalancedPoolOptions`
Extends: [`PoolOptions`](Pool.md#parameter-pooloptions)
* **factory** `(origin: URL, opts: Object) => Dispatcher` - Default: `(origin, opts) => new Pool(origin, opts)`
The `PoolOptions` are passed to each of the `Pool` instances being created.
## Instance Properties
### `BalancedPool.upstreams`
Returns an array of upstreams that were previously added.
### `BalancedPool.closed`
Implements [Client.closed](Client.md#clientclosed)
### `BalancedPool.destroyed`
Implements [Client.destroyed](Client.md#clientdestroyed)
### `Pool.stats`
Returns [`PoolStats`](PoolStats.md) instance for this pool.
## Instance Methods
### `BalancedPool.addUpstream(upstream)`
Add an upstream.
Arguments:
* **upstream** `string` - It should only include the **protocol, hostname, and port**.
### `BalancedPool.removeUpstream(upstream)`
Removes an upstream that was previously addded.
### `BalancedPool.close([callback])`
Implements [`Dispatcher.close([callback])`](Dispatcher.md#dispatcherclosecallback-promise).
### `BalancedPool.destroy([error, callback])`
Implements [`Dispatcher.destroy([error, callback])`](Dispatcher.md#dispatcherdestroyerror-callback-promise).
### `BalancedPool.connect(options[, callback])`
See [`Dispatcher.connect(options[, callback])`](Dispatcher.md#dispatcherconnectoptions-callback).
### `BalancedPool.dispatch(options, handlers)`
Implements [`Dispatcher.dispatch(options, handlers)`](Dispatcher.md#dispatcherdispatchoptions-handler).
### `BalancedPool.pipeline(options, handler)`
See [`Dispatcher.pipeline(options, handler)`](Dispatcher.md#dispatcherpipelineoptions-handler).
### `BalancedPool.request(options[, callback])`
See [`Dispatcher.request(options [, callback])`](Dispatcher.md#dispatcherrequestoptions-callback).
### `BalancedPool.stream(options, factory[, callback])`
See [`Dispatcher.stream(options, factory[, callback])`](Dispatcher.md#dispatcherstreamoptions-factory-callback).
### `BalancedPool.upgrade(options[, callback])`
See [`Dispatcher.upgrade(options[, callback])`](Dispatcher.md#dispatcherupgradeoptions-callback).
## Instance Events
### Event: `'connect'`
See [Dispatcher Event: `'connect'`](Dispatcher.md#event-connect).
### Event: `'disconnect'`
See [Dispatcher Event: `'disconnect'`](Dispatcher.md#event-disconnect).
### Event: `'drain'`
See [Dispatcher Event: `'drain'`](Dispatcher.md#event-drain).
