Lambdas randomly not being invoked from another lambda

Hey people!

I have stumbled upon an unusual problem. Explained simply, I have two lambdas:

  1. A lambda that reacts to a .csv uploaded to a designated S3 bucket, that gets it and parses the file, reading the file line by line and invoking lambda n° 2 for each.
  2. This lambda simply puts the information of the received, parsed csv line into an RDS database.

The .csv I am working with currently has somewhere near 1500 lines. The problem that I have noticed is that lambda n°2 is not being invoked for every line (lambda console always shows less invocations than the number of lines in the file), for some reason that I really can’t uncover. The whole file is being read, of that I am sure. Since I am in us-east-1, it isn’t a throttle issue. Also, no dead letter queue problems either. I got the permissions figured out, so yeah, not that as well.

Should you need any clarifications or code samples, please ask. If you could at least point me in the right direction, it would help me greatly!

Thank you so much!