# FairshareSchedulingPolicy

Represents a Fairshare Scheduling Policy. Instructs the scheduler to allocate ComputeEnvironment vCPUs based on Job shareIdentifiers.

The Faireshare Scheduling Policy ensures that each share gets a certain amount of vCPUs.
The scheduler does this by deciding how many Jobs of each share to schedule *relative to how many jobs of
each share are currently being executed by the ComputeEnvironment*. The weight factors associated with
each share determine the ratio of vCPUs allocated; see the readme for a more in-depth discussion of
fairshare policies.

Extends: Construct › Resource › FairshareSchedulingPolicy
Implements: IResource, IFairshareSchedulingPolicy, ISchedulingPolicy, IEnvironmentAware, ISchedulingPolicyRef, IConstruct, IDependable

- CloudFormation: [`AWS::Batch::SchedulingPolicy`](https://docs.aws.amazon.com/AWSCloudFormation/latest/TemplateReference/aws-resource-batch-schedulingpolicy.html)
- L1 type: [`CfnSchedulingPolicy`](/cdk/api/v2/docs/aws-cdk-lib.aws_batch.CfnSchedulingPolicy.html)
- Source: [`aws-batch/lib/scheduling-policy.ts`](https://github.com/aws/aws-cdk/blob/v2.274.0/packages/aws-cdk-lib/aws-batch/lib/scheduling-policy.ts#L206)
- Type last changed: v2.234.0 · 8 Jan 2026

## Example

```ts
const fairsharePolicy = new batch.FairshareSchedulingPolicy(this, 'myFairsharePolicy');

fairsharePolicy.addShare({
  shareIdentifier: 'A',
  weightFactor: 1,
});
fairsharePolicy.addShare({
  shareIdentifier: 'B',
  weightFactor: 1,
});
new batch.JobQueue(this, 'JobQueue', {
  schedulingPolicy: fairsharePolicy,
});
```

## Initializer

```ts
new FairshareSchedulingPolicy(scope: Construct, id: string, props?: FairshareSchedulingPolicyProps)
```

## Construct Props

- `computeReservation`: number — Used to calculate the percentage of the maximum available vCPU to reserve for share identifiers not present in the Queue.

  **Default:** no vCPU is reserved

  The percentage reserved is defined by the Scheduler as:
  `(computeReservation/100)^ActiveFairShares` where `ActiveFairShares` is the number of active fair share identifiers.

  For example, a computeReservation value of 50 indicates that AWS Batch reserves 50% of the
  maximum available vCPU if there's only one fair share identifier.
  It reserves 25% if there are two fair share identifiers.
  It reserves 12.5% if there are three fair share identifiers.

  A computeReservation value of 25 indicates that AWS Batch should reserve 25% of the
  maximum available vCPU if there's only one fair share identifier,
  6.25% if there are two fair share identifiers,
  and 1.56% if there are three fair share identifiers.

- `schedulingPolicyName`: string — The name of this SchedulingPolicy.

  **Default:** generated by CloudFormation

- `shareDecay`: [Duration](/cdk/api/v2/docs/aws-cdk-lib.Duration.html) — The amount of time to use to measure the usage of each job.

  **Default:** 0: only the current job usage is considered

  The usage is used to calculate a fair share percentage for each fair share identifier currently in the Queue.
  A value of zero (0) indicates that only current usage is measured.
  The decay is linear and gives preference to newer jobs.

  The maximum supported value is 604800 seconds (1 week).

- `shares`: [Share](/cdk/api/v2/docs/aws-cdk-lib.aws_batch.Share.html)[] — The shares that this Scheduling Policy applies to.

  **Default:** no shares

  *Note*: It is possible to submit Jobs to the queue with Share Identifiers that
  are not recognized by the Scheduling Policy.

## Properties

- `computeReservation`: number — Used to calculate the percentage of the maximum available vCPU to reserve for share identifiers not present in the Queue.

  The percentage reserved is defined by the Scheduler as:
  `(computeReservation/100)^ActiveFairShares` where `ActiveFairShares` is the number of active fair share identifiers.

  For example, a computeReservation value of 50 indicates that AWS Batch reserves 50% of the
  maximum available vCPU if there's only one fair share identifier.
  It reserves 25% if there are two fair share identifiers.
  It reserves 12.5% if there are three fair share identifiers.

  A computeReservation value of 25 indicates that AWS Batch should reserve 25% of the
  maximum available vCPU if there's only one fair share identifier,
  6.25% if there are two fair share identifiers,
  and 1.56% if there are three fair share identifiers.

- `env`: [ResourceEnvironment](/cdk/api/v2/docs/aws-cdk-lib.interfaces.ResourceEnvironment.html) (required) — The environment this resource belongs to.

  For resources that are created and managed in a Stack (those created by
  creating new class instances like `new Role()`, `new Bucket()`, etc.), this
  is always the same as the environment of the stack they belong to.

  For referenced resources (those obtained from referencing methods like
  `Role.fromRoleArn()`, `Bucket.fromBucketName()`, etc.), they might be
  different than the stack they were imported into.

- `node`: [Node](/cdk/api/v2/docs/constructs.Node.html) (required) — The tree node.

- `PROPERTY_INJECTION_ID`: string (required) (static) — Uniquely identifies this class.

- `schedulingPolicyArn`: string (required) — The arn of this scheduling policy.

- `schedulingPolicyName`: string (required) — The name of this scheduling policy.

- `schedulingPolicyRef`: [SchedulingPolicyReference](/cdk/api/v2/docs/aws-cdk-lib.interfaces.aws_batch.SchedulingPolicyReference.html) (required) — A reference to a SchedulingPolicy resource.

- `shareDecay`: [Duration](/cdk/api/v2/docs/aws-cdk-lib.Duration.html) — The amount of time to use to measure the usage of each job.

  The usage is used to calculate a fair share percentage for each fair share identifier currently in the Queue.
  A value of zero (0) indicates that only current usage is measured.
  The decay is linear and gives preference to newer jobs.

  The maximum supported value is 604800 seconds (1 week).

- `shares`: [Share](/cdk/api/v2/docs/aws-cdk-lib.aws_batch.Share.html)[] (required) — The shares that this Scheduling Policy applies to.

  *Note*: It is possible to submit Jobs to the queue with Share Identifiers that
  are not recognized by the Scheduling Policy.

- `stack`: [Stack](/cdk/api/v2/docs/aws-cdk-lib.Stack.html) (required) — The stack in which this resource is defined.

## Methods

- `addShare(share: Share): void` — Add a share this to this Fairshare SchedulingPolicy.

- `applyCrossStackReferenceStrength(strength: ReferenceStrength): void` — Override the cross-stack reference strength for this resource.

  When set, any cross-stack reference to this resource will use the specified
  mechanism instead of the global default determined by the
  `@aws-cdk/core:defaultCrossStackReferences` context key. This is useful for
  selectively weakening specific references to avoid the "deadly embrace" problem
  without changing the app-wide default.

  **Parameters**

  - `strength` — - The reference strength to use for this resource.

- `applyRemovalPolicy(policy: RemovalPolicy): void` — Apply the given removal policy to this resource.

  The Removal Policy controls what happens to this resource when it stops
  being managed by CloudFormation, either because you've removed it from the
  CDK application or because you've made a change that requires the resource
  to be replaced.

  The resource can be deleted (`RemovalPolicy.DESTROY`), or left in your AWS
  account for data recovery and cleanup later (`RemovalPolicy.RETAIN`).

- `fromFairshareSchedulingPolicyArn(scope: Construct, id: string, fairshareSchedulingPolicyArn: string): IFairshareSchedulingPolicy` (static) — Reference an existing Scheduling Policy by its ARN.

- `isConstruct(x: any): boolean` (static) — Checks if `x` is a construct.

  Use this method instead of `instanceof` to properly detect `Construct`
  instances, even when the construct library is symlinked.

  Explanation: in JavaScript, multiple copies of the `constructs` library on
  disk are seen as independent, completely different libraries. As a
  consequence, the class `Construct` in each copy of the `constructs` library
  is seen as a different class, and an instance of one class will not test as
  `instanceof` the other class. `npm install` will not create installations
  like this, but users may manually symlink construct libraries together or
  use a monorepo tool: in those cases, multiple copies of the `constructs`
  library can be accidentally installed, and `instanceof` will behave
  unpredictably. It is safest to avoid using `instanceof`, and using
  this type-testing method instead.

  **Parameters**

  - `x` — Any object.

  **Returns:** true if `x` is an object created from a class which extends `Construct`.

- `isOwnedResource(construct: IConstruct): boolean` (static) — Returns true if the construct was created by CDK, and false otherwise.

- `isResource(construct: IConstruct): boolean` (static) — Check whether the given construct is a Resource.

- `toString(): string` — Returns a string representation of this construct.

- `with(...mixins: IMixin[]): IConstruct` — Applies one or more mixins to this construct.

  Mixins are applied in order. The list of constructs is captured at the
  start of the call, so constructs added by a mixin will not be visited.
  Use multiple `with()` calls if subsequent mixins should apply to added
  constructs.