Lambda and concurrent execution quotas

[ClaireS]

Hi all, I don’t understand the rationale given for a particular question. It’s to do with Lambda scaling approach and concurrent executions. The rationale includes the following:

You can use this formula to estimate the capacity used by your function:

concurrent executions = (invocations per second) x (average execution duration in seconds)

However, when I read the documentation, I understand that Lambda will start a new instance for each new invocations until it reaches a concurrency limit (assume this is after the initial burst)

<div>I don’t understand where the above formula comes from? Any further help to understand greatly appreciated.
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Thanks all,

Claire

[Carlo-TutorialsDojo]

Hello Claire,

Thanks for posting your question.

Could you provide the exact question or a screenshot of the question that you’re referring to?

[ClaireS]

Hi Carlo,

Thanks for your reply. I can answer my own question now 🙂

It was Review Mode Set 1 – AWS Certified Developer Associate > Question 19 (see attached)

I understand how the formula in the rationale given is working (I got the answer right; I just didn’t follow the rationale).

It was best for me to consider a timeline: 1s = 10 invocations, 2 = 20, 3 = 30, 4 = 40, … , 10 = 100, and thereafter the formula roughly works out (as this is all averages in any case). Therefore,

= 10 invocations per second * 10 seconds average duration

= 100 concurrent executions (after 10 seconds…)

Thanks,

Claire

[Carlo-TutorialsDojo]

Hello Claire,

Thanks for the follow-up.

That’s great to know.

Let me know if you have other queries.

Regards,

Carlo