Lambda powertool SSMProvider is either increasing cold start time or unable to refresh parameters about powertools-lambda-java HOT 5 CLOSED

Hi,

Thanks for reporting this.

The constructor won't be called in a warmed function, the call to SSM will be done once during cold start. So whatever the maxAge you set, it doesn't really matter, params will remain the same while the function is warmed.

In the handler, with your code I had the following results:
cold start: 3+ seconds (~3400 ms)
warm start: single-digit ms (~2-3 ms)
warm start after 1 min (reload params): ~200-300 ms

I replaced powertools-param with an similar call to ssm:

• In the constructor:

ssmClient = SsmClient.builder() .httpClientBuilder(UrlConnectionHttpClient.builder()) .credentialsProvider(EnvironmentVariableCredentialsProvider.create()) .region(Region.of(System.getenv(SdkSystemSetting.AWS_REGION.environmentVariable()))) .build();

• In the handler:

GetParametersByPathResponse params = ssmClient.getParametersByPath(GetParametersByPathRequest.builder().path("/powertools-java/sample").recursive(true).withDecryption(true).build());

And had exactly the same results (few ms difference):
cold start: 3+ seconds (~3300 ms)
warm start: 200-300 ms (each time)

Unfortunately, we cannot improve the call to SSM itself, but thanks to the cache, it reduces the time from 200-300ms to 2-3ms during the time of the cache. Then, you need to find the best TTL for your use case.

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Thanks @jeromevdl for taking out some time for this.
Yes, I agree cache does help to improve performance during warm state.

As a workaround, we can also force a cold restart on Lambda function by changing an environment variable whenever there is an update on SSM parameter. We can also avoid additional cold start time using this approach.

My question is, does it impact any existing lambda invocations that are in progress, in any way?

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Functions currently running are not impacted by an update, they will finish with current version/configuration.

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Thanks @jeromevdl for confirming.

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@deepti-tyagi I believe we can close this issue for now based on above discussion. Thanks for using powertools. Feel free to open an issue in case of any questions/issues/feedback. :)

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