AWS Lambda Reserved Concurrency vs Retry

Creating a test lambda

"name": "Some name",
"numberOfSecondsToWait": 5
  1. Log the value of the name property.
  2. Waits for numberOfSecondsToWait seconds.

Invoking the lambda

  • Both requests (Long 1, and Long 2) were executed one after the other.
  • It took some time (about 5 minutes) for Long 2 to start once Long 1 was completed.

Warning: retry of errors raised by your code


  • With InvocationType=RequestResponse, I will receive an error. I have to retry the operation myself.
  • With InvocationType=Event, my request will succeed. It will be retried by AWS (for up to 6 hours).
  • create a lambda with ReserveConcurrency=1
  • put my heavy processing in that lambda
  • start that lambda with InvocationType=Event whenever the big operation is needed




Back end developer at LANDR Music

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Maxime Beaudry

Maxime Beaudry

Back end developer at LANDR Music

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