@loopback/docs/site/apidocs/pooling.poolingservice.md

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---
lang: en
title: 'API docs: pooling.poolingservice'
keywords: LoopBack 4.0, LoopBack 4, Node.js, TypeScript, OpenAPI
sidebar: lb4_sidebar
editurl: https://github.com/loopbackio/loopback-next/tree/master/extensions/pooling
permalink: /doc/en/lb4/apidocs.pooling.poolingservice.html
---

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[Home](./index.md) &gt; [@loopback/pooling](./pooling.md) &gt; [PoolingService](./pooling.poolingservice.md)

## PoolingService class

A singleton service to maintain a pool of resources. This pool service can be bound to different keys to represent multiple pools. Each binding is a singleton so that the state stays the same for injections into multiple instances for other artifacts.

<b>Signature:</b>

```typescript
export declare class PoolingService<T> implements LifeCycleObserver 
```
<b>Implements:</b> [LifeCycleObserver](./core.lifecycleobserver.md)

## Remarks

Some resources can be expensive to create/start. For example, a datasource has overhead to connect to the database. There will be performance penalty to use `TRANSIENT` scope and creates a new instance per request. But it is not feasible to be a singleton for some use cases, for example, each request may have different security contexts.

The pool service observes life cycle events to start and stop.

## Constructors

|  Constructor | Modifiers | Description |
|  --- | --- | --- |
|  [(constructor)(context, options)](./pooling.poolingservice._constructor_.md) |  | Constructs a new instance of the <code>PoolingService</code> class |

## Properties

|  Property | Modifiers | Type | Description |
|  --- | --- | --- | --- |
|  [context](./pooling.poolingservice.context.md) |  | [Context](./context.context.md) |  |
|  [pool](./pooling.poolingservice.pool.md) |  | Pool&lt;T&gt; | The resource pool |

## Methods

|  Method | Modifiers | Description |
|  --- | --- | --- |
|  [acquire(requestCtx)](./pooling.poolingservice.acquire.md) |  | Acquire a new instance |
|  [destroy(resource)](./pooling.poolingservice.destroy.md) |  | Destroy a resource from the pool |
|  [release(resource)](./pooling.poolingservice.release.md) |  | Release the resource back to the pool. |
|  [run(task, requestCtx)](./pooling.poolingservice.run.md) |  | Run the task with an acquired resource from the pool. If task is completed successfully, the resource is returned to the pool. Otherwise, the resource is destroyed. |
|  [start()](./pooling.poolingservice.start.md) |  | Start the pool |
|  [stop()](./pooling.poolingservice.stop.md) |  | Stop the pool |