AWS Lambda迭代器年龄报警从未触发

我们为AWS Lambda Itreator age设置了一个CloudWatch警报,但由于某些原因从未触发。即使迭代器的年龄肯定超过了阈值。以下是用于此警报的CloudFormation模板的一部分:

"TreatMissingData": "missing",
"ComparisonOperator": "GreaterThanOrEqualToThreshold",
"Dimensions": [{
    "Name": "FunctionName",
    "Value": {
        "Ref": "LambdaFunction"
    }
}],
"EvaluationPeriods": 1,
"InsufficientDataActions": [],
"MetricName": "IteratorAge",
"Namespace": "AWS/Lambda",
"OKActions": [{
    "Ref": "NotificationTopic"
}],
"Period": 900,
"Statistic": "Minimum",
"Threshold": 1800000,
"Unit": "Microseconds"