Why is there a 15 minute limit for how long the AWS lambda code can execute?

[Monica Shiralkar]

AWS lambda can run for a maximum of 15 minutes.  Reference : https://aws.amazon.com/lambda/faqs/#:~:text=Q%3A%20How%20long%20can%20an,1%20second%20and%2015%20minutes.

Why is there a 15 minute limit on how long the AWS lambda code can run?  I had also read about a limit in case of Azure Functions (the equivalent of AWS lambda on Azure). Why are those not allowed to run for long time?

Thanks.

[Stephan van Hulst]

Two reasons I can think of.

If lambda's didn't have a known hard limit, when would Amazon be allowed to scale down their running servers?

Wouldn't you be upset if you accidentally wrote a lambda that executed indefinitely, and Amazon charged you for it?

[Tim Moores]

Long running jobs likely have different execution properties than lambdas. AWS Batch is probably better suited for those than AWS Lambda.

[Monica Shiralkar]

Tim Moores wrote:Long running jobs likely have different execution properties than lambdas. AWS Batch is probably better suited for those than AWS Lambda.

Thanks. Okay, AWS batch which is another PAAS (but not serverless and does not involve auto scaling). Yes, since AWS lambda does automatic scaling long running jobs is not an option.

[Monica Shiralkar]

Stephan van Hulst wrote:

If lambda's didn't have a known hard limit, when would Amazon be allowed to scale down their running servers?

Wouldn't you be upset if you accidentally wrote a lambda that executed indefinitely, and Amazon charged you for it?

Thanks. I couldn't find the reasons on the AWS documentation but the ones you listed seems logical.