Bug: Subsegment ssm discarded due to Lambda worker still initializing

Expected Behaviour

The expected behavior would be to not receive this warning message

Current Behaviour

• Receiving an intermittent warning, stating “Subsegment ssm discarded due to Lambda worker still initializing”, followed by another warning stating “No subsegment to end.” These appear to be raised by the powertools Parameters utility.
• I am doing the parameter retrieval before the lambda handler (global scope) since this will not change very often, regardless of execution environment, as demonstrated below.

Code snippet

from aws_lambda_powertools.utilities import parameters
import boto3

config = Config(
   retries = {
      'max_attempts': 15,
      'mode': 'standard'
   }
)
client=boto3.client('rekognition', config=config)
model_arn=parameters.get_parameter('/RekCL/MODEL_ARN', max_age=300)

def lambda_handler(event, context):
  try:
        response = client.detect_custom_labels(
            ProjectVersionArn=model_arn,
            Image={'S3Object':{'Bucket':bucket,'Name':photo}})

 # etc...

Possible Solution

Please see this: https://github.com/aws/aws-xray-sdk-python/issues/331

I believe there is a check here, but I don’t see anything in the powertools docs that says I need to have x-ray enabled.

Steps to Reproduce

retrieve a parameter in a lambda function, with global scope (before lambda handler)

AWS Lambda Powertools for Python version

latest

AWS Lambda function runtime

3.9

Packaging format used

Lambda Layers

Debugging logs

No response

[94Sip]

Hi @94Sip thanka for flagging this - IIRC this is an issue in X-Ray SDK which hasn’t been resolved yet (I’ll use this as a basis for a repro).

In the meantime, you can safely add the get_parameter inside the handler, because only the first call will be made to SSM.

We keep that in-memory and it’ll only fetch another call if Lambda spins up another container (concurrency), which is also true for a new cold start to happen.

Thank you for this quick reply - moving the call to the handler appears to have resolved this warning being thrown.

[94Sip]

A few more updates:

This lambda is being orchestrated by a Step Function that has x-ray tracing enabled. I have enabled x-ray on the lambda function AND added the appropriate policy, as described here: https://docs.aws.amazon.com/lambda/latest/dg/services-xray.html

Still receiving the intermittent warning.