aws lambda concurrent executions limitations

The AWS Lambda service has concurrency limitations to limit the number of functions that can be run simultaneously within a given region, per account.

Concurrent executions

• Default is 1,000 per region
• Error message is TooManyRequestsException
• HTTP status code: 429
• Request throughput limit to be increased
  • This can be requested through the AWS Support Center
• Reserved concurrency guarantees that a set number of executions which will always

be available for your critical function, however this also acts as a limit