Amazon ECS service throttle logic - Amazon Elastic Container Service
Resolving throttling issues

Amazon ECS service throttle logic

The Amazon ECS service scheduler includes protective logic that throttles task launches when tasks repeatedly fail to start. This helps prevent unnecessary resource consumption and reduces costs.

When tasks in a service fail to transition from PENDING to RUNNING state and instead move directly to STOPPED, the scheduler:

  • Incrementally increases the time between restart attempts

  • Continues increasing delays up to a maximum of 27 minutes between attempts

  • Generates a service event message to notify you of the issue

Note

The maximum delay period of 27 minutes may change in future updates.

When throttling is activated, you receive this service event message:

(service service-name) is unable to consistently start tasks successfully.

Important characteristics of the throttle logic:

  • Services continue retry attempts indefinitely

  • The only modification is the increased time between restarts

  • There are no user-configurable parameters

Resolving throttling issues

To resolve throttling, you can:

  • Update the service to use a new task definition, which immediately returns the service to normal, non-throttled operation. For more information, see Updating an Amazon ECS service.

  • Address the underlying cause of the task failures.

Common causes of task failures that trigger throttling include:

Important

The following scenarios do NOT trigger throttle logic:

  • Tasks that stop after reaching RUNNING state

  • Tasks stopped due to failed Elastic Load Balancing health checks

  • Tasks where the container command exits with a non-zero code after reaching RUNNING state