US Patent 10942795 Serverless call distribution to utilize reserved capacity without inhibiting scaling

Systems and methods are described for reducing cold starts code within a serverless code execution system by providing a set of environments reserved for the code. A frontend utilizes a consistent hash ring to distribute calls for execution among a set of manager devices that manage environments in the system, distributed in a manner that groups calls together and attempts to distribute calls of the same group to a stable subset of the manager devices. Each group is assigned an arc, representing a subset of manager devices. When a call is received to execute a set of code that has environments reserved, the frontend distributes the call to a manager device of a reserved arc. When a call is received to execute a set of code that does not have environment reserved, the frontend distributes the call to an arc associated with an arc for unreserved executions.