Calling AmazonS3Client.GetObjectAsync() on lambda function take too long (~5s) on the first invoke

[hoainam1593]

Describe the bug

I'm using S3 client in lambda function, this is my code:

public class SomeLambdaFunction
{
    public async Task<string> Handler(string input, ILambdaContext context)
    {
        var client = new AmazonS3Client();
        // begin stop watch
        await client.GetObjectAsync("<bucket-name>", "<object-key>");
        //end stopwatch and see took ~5s
    }
}

when I deploy and invoke in the first time, it took ~5s to execute client.GetObjectAsync, when I run later (reuse lambda instance), it complete instantly

Expected Behavior

AmazonS3Client.GetObjectAsync complete instantly on any invoke

Current Behavior

AmazonS3Client.GetObjectAsync take too long in the first invoke

Reproduction Steps

• write lambda function using S3
• call a S3 API after deploy
• do benchmark that calling and see that calling take too long

Possible Solution

No response

Additional Information/Context

No response

AWS .NET SDK and/or Package version used

AWSSDK.S3 3.7.304.1

Targeted .NET Platform

.net 6.0

Operating System and version

lambda environment

[ashishdhingra]

@hoainam1593 Good morning. Thanks for opening the issue. The 1st invocation could take long due to Lambda cold start times, also you confirmed that the subsequent executions happen almost instantaneously. You may also try temporarily enabling verbose logging to see any SDK logic causing delay using code below:

Amazon.AWSConfigs.LoggingConfig.LogResponses = Amazon.ResponseLoggingOption.Always;
Amazon.AWSConfigs.LoggingConfig.LogTo = Amazon.LoggingOptions.Console;
Amazon.AWSConfigs.AddTraceListener("Amazon", new System.Diagnostics.ConsoleTraceListener());

Thanks,
Ashish

[hoainam1593]

Thanks for your answer.
I'm aware of cold start issue of lambda function, but I thought it happen before lambda's handler actually run, does cold start really happen inside lambda's handler? @ashishdhingra

about the operation taking too long (~5s), it's just function to get S3 object:
await client.GetObjectAsync("", "");

[ashishdhingra]

@hoainam1593 Good morning. Thanks for opening the issue. The 1st invocation could take long due to Lambda cold start times, also you confirmed that the subsequent executions happen almost instantaneously. You may also try temporarily enabling verbose logging to see any SDK logic causing delay using code below:

Amazon.AWSConfigs.LoggingConfig.LogResponses = Amazon.ResponseLoggingOption.Always;
Amazon.AWSConfigs.LoggingConfig.LogTo = Amazon.LoggingOptions.Console;
Amazon.AWSConfigs.AddTraceListener("Amazon", new System.Diagnostics.ConsoleTraceListener());

Thanks, Ashish

@hoainam1593 Could you please share the Lambda memory settings as well?

[hoainam1593]

I used the lowest one 128MB

[ashishdhingra]

@hoainam1593 We recently pushed a new version AWSSDK.Core version 3.7.300.18 that contained fix for performance degradation reported as part of another issue. Could you please check if upgrading to this version (or later) fixes your issue?

Thanks,
Ashish

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