Understanding AWS Lambda proactive initialization

AWS Lambda occasionally pre-initializes execution environments to reduce the number of cold start invocations. This feature is known as proactive initialization and can be observed in functions using unreserved (on-demand) concurrency. Proactive initialization serves both the interests of AWS and developers running applications on Lambda, as it minimizes the time spent on initializing functions that will serve invocations. The percentage of true cold start initializations to proactive initializations varies depending on many factors, but you can clearly observe it. Depending on your workload and latency tolerance, you may need Provisioned Concurrency. AWS Lambda functions without steady traffic do not typically benefit from proactive initializations, while functions with more traffic tend to have a higher percentage of proactive initializations.