One of the primary systems in the Lambda architecture is called a worker. It’s where AWS provisions a secure environment and enables the customer code execution.
Mesrobian explained that what the worker does, is it creates and manages a collection of sandboxes and sets limits on those boxes, such as memory and CPU available for function execution. The worker downloads the customer code, announces it for execution, and it also manages multiple language runtimes. The worker also executes the customer code through initialization and invocation and finally it manages agents for monitoring and operational controls like AWS CloudWatch.