状态机中的错误处理与重试

A Step Functions workflow chains many tasks. Any task can fail — a timeout, a throttle, or a thrown error. Built-in error handling lets the state machine recover instead of crashing.

Step Functions classifies errors with names like States.Timeout, States.TaskFailed, and States.ALL. Your custom Lambda errors appear by their error name too.

A Retry array on a Task state automatically re-runs it on matching errors.

Use IntervalSeconds and BackoffRate so each retry waits longer, easing pressure on a struggling downstream service.

When retries are exhausted, a Catch block routes the workflow to a fallback state instead of failing the whole execution.

Use ResultPath in a Catch to pass the error details into the next state, so your fallback can log or react to what went wrong.

List more specific errors first. Step Functions evaluates Retry/Catch entries top to bottom, so a broad States.ALL should come last.

Set TimeoutSeconds on a Task so a hung activity throws States.Timeout instead of running forever, which your Retry can then handle.

A fallback can be a Fail state that ends the execution with a clear cause, or a compensating action that undoes earlier work (the saga pattern).

Standard workflows keep full execution history for debugging failures; Express workflows are faster and cheaper but log to CloudWatch. Choose based on how you need to trace errors.

Combine the tools:

• Retry transient errors with backoff
• Catch terminal errors to a fallback
• Set timeouts as safety nets
• Capture error details with ResultPath

You learned resilient workflows:

• Retry re-runs tasks on matching error names
• IntervalSeconds and BackoffRate give exponential backoff
• Catch routes exhausted errors to a fallback state
• ResultPath captures the error; timeouts prevent hangs