# Class: `Kernels`

[@jupyterlite/kernel](../modules/jupyterlite_kernel.md).Kernels

A class to handle requests to /api/kernels

## Implements

- [`IKernels`](../modules/jupyterlite_kernel.md#ikernels)

## Constructors

### `constructor`

> **`new Kernels`**(`options`)

Construct a new Kernels

#### Parameters

| Name      | Type                                                               | Description               |
| :-------- | :----------------------------------------------------------------- | :------------------------ |
| `options` | [`IOptions`](../interfaces/jupyterlite_kernel.Kernels.IOptions.md) | The instantiation options |

#### Defined in

[packages/kernel/src/kernels.ts:26](https://github.com/jupyterlite/jupyterlite/blob/7971e0aa/packages/kernel/src/kernels.ts#L26)

## Properties

### `_clients`

> `Private` **`_clients`**: `ObservableMap`<`Client`\>

#### Defined in

[packages/kernel/src/kernels.ts:208](https://github.com/jupyterlite/jupyterlite/blob/7971e0aa/packages/kernel/src/kernels.ts#L208)

### `_kernelClients`

> `Private` **`_kernelClients`**: `ObservableMap`<`Set`<`string`\>\>

#### Defined in

[packages/kernel/src/kernels.ts:209](https://github.com/jupyterlite/jupyterlite/blob/7971e0aa/packages/kernel/src/kernels.ts#L209)

### `_kernels`

> `Private` **`_kernels`**:
> `ObservableMap`<[`IKernel`](../interfaces/jupyterlite_kernel.IKernel-1.md)\>

#### Defined in

[packages/kernel/src/kernels.ts:207](https://github.com/jupyterlite/jupyterlite/blob/7971e0aa/packages/kernel/src/kernels.ts#L207)

### `_kernelspecs`

> `Private` **`_kernelspecs`**:
> [`IKernelSpecs`](../modules/jupyterlite_kernel.md#ikernelspecs)

#### Defined in

[packages/kernel/src/kernels.ts:210](https://github.com/jupyterlite/jupyterlite/blob/7971e0aa/packages/kernel/src/kernels.ts#L210)

## Methods

### `restart`

> **`restart`**(`kernelId`): `Promise`<`IModel`\>

Restart a kernel.

#### Parameters

| Name       | Type     | Description    |
| :--------- | :------- | :------------- |
| `kernelId` | `string` | The kernel id. |

#### Returns

`Promise`<`IModel`\>

#### Implementation of

IKernels.restart

#### Defined in

[packages/kernel/src/kernels.ts:188](https://github.com/jupyterlite/jupyterlite/blob/7971e0aa/packages/kernel/src/kernels.ts#L188)

### `shutdown`

> **`shutdown`**(`id`): `Promise`<`void`\>

Shut down a kernel.

#### Parameters

| Name | Type     | Description    |
| :--- | :------- | :------------- |
| `id` | `string` | The kernel id. |

#### Returns

`Promise`<`void`\>

#### Implementation of

IKernels.shutdown

#### Defined in

[packages/kernel/src/kernels.ts:203](https://github.com/jupyterlite/jupyterlite/blob/7971e0aa/packages/kernel/src/kernels.ts#L203)

### `startNew`

> **`startNew`**(`options`): `Promise`<`IModel`\>

Start a new kernel.

#### Parameters

| Name      | Type                                                                           | Description               |
| :-------- | :----------------------------------------------------------------------------- | :------------------------ |
| `options` | [`IKernelOptions`](../interfaces/jupyterlite_kernel.Kernels.IKernelOptions.md) | The kernel start options. |

#### Returns

`Promise`<`IModel`\>

#### Implementation of

IKernels.startNew

#### Defined in

[packages/kernel/src/kernels.ts:36](https://github.com/jupyterlite/jupyterlite/blob/7971e0aa/packages/kernel/src/kernels.ts#L36)