Adjusting variable limit on concurrent code executions

A computer-implemented method to provide scaling of computational capacity on an on-demand code execution environment, the computer-implemented method comprising:

• receiving a request to execute a program code on the on-demand code execution environment, the request including client information identifying the client associated with the program code, the client associated with a set of virtual machine instance managers configured to acquire compute capacity on behalf of the client;
• identifying, using a hash value calculated based on the client information, a first virtual machine manager assigned to the user from the set of virtual machine instance managers;
• requesting the a first virtual machine instance manager in the set of virtual machine instance managers to acquire compute capacity for executing the program code on behalf of the client;
• receiving a response indicating that the first virtual machine instance manager did not successfully acquire compute capacity for executing the program code on behalf of the client;
• causing a second virtual machine instance manager different from the first virtual machine instance manager to be added to the set of virtual machine instance managers configured to acquire compute capacity on behalf of the client;
• and
• causing the program code to be executed on behalf of the client on a virtual machine instance acquired by the second virtual machine instance manager.

Non-transitory physical computer storage including computer-executable instructions that, when executed by a computing system, cause the computing system to:

• receive a request to execute a program code on an on-demand code execution environment, the request including client information identifying the client associated with the program code, the client associated with a set of virtual machine instance managers configured to acquire compute capacity on behalf of the client;
• identify, using a hash value calculated based on the client information, a first virtual machine manager assigned to the user from the set of virtual machine instance managers;
• request the first virtual machine instance manager in the set of virtual machine instance managers to acquire compute capacity for executing the program code on behalf of the client;
• receive a response indicating that the first virtual machine instance manager did not successfully acquire compute capacity for executing the program code on behalf of the client;
• cause a second virtual machine instance manager different from the first virtual machine instance manager to be added to the set of virtual machine instance managers configured to acquire compute capacity on behalf of the client;
• and
• cause the program code to be executed on behalf of the client on a virtual machine instance acquired by the second virtual machine instance manager.