AWS Step Functions
Developer Guide

Use Timeouts to Avoid Stuck Executions

By default, the Amazon States Language doesn't set timeouts in state machine definitions. Without an explicit timeout, Step Functions often relies solely on a response from an activity worker to know that a task is complete. If something goes wrong and TimeoutSeconds isn't specified, an execution is stuck waiting for a response that will never come.

To avoid this, specify a reasonable timeout limit when you create a task in your state machine. For example:

"ActivityState": { "Type": "Task", "Resource": "arn:aws:states:us-east-1:123456789012:activity:HelloWorld", "TimeoutSeconds": 300, "HeartbeatSeconds": 60, "Next": "NextState" }

For more information, see Task in the Amazon States Language documentation.