Managing shared computing environments

A non-transitory computer-readable medium having stored contents including executable software instructions that, when executed by a computing system, program the computing system to perform a method, the method comprising:

• receiving, by a program execution service that is being provided at least in part by the programmed computing system and that has multiple users, instructions from a first user of the multiple users to execute one or more indicated software programs to provide a first computing environment that include an indicated type of functionality and that is available for use by other users of the multiple users;
• selecting, by the program execution service, a first host computing node from a plurality of computing nodes that are provided by the program execution service for use by the multiple users, and provisioning the first host computing node to execute the one or more indicated software programs for the first user, wherein the first host computing node is a virtual machine hosted by a server computing system of the program execution service;
• providing, by the program execution service, the first computing environment for the first user by executing the indicated one or more software programs on the first host computing node;
• and
• while the providing of the first computing environment on the first host computing node for the first user continues,
• receiving, by the program execution service and from an additional user of the multiple users, a request to execute an additional program for the additional user using the indicated type of functionality;
• determining, by the program execution service and based on one or more specified criteria, to execute the additional program for the additional user on the first host computing node as part of the first computing environment instead of on a separate second host computing node of the plurality without any other programs of any other users;
• and
• executing, by the program execution service and based at least in part on the determining, the additional program on the first host computing node, and accessing, by the executing additional program, the indicated type of functionality from the first computing environment of the first user on the first host computing node.

A system comprising:

• one or more processors of one or more computer systems;
• and
• one or more memories including software instructions that, when executed by at least one of the one or more processors, configure the at least one processor to provide functionality of a program execution service having multiple users, including:
• receiving instructions sent to the program execution service from a first user of the multiple users to execute one or more indicated software programs for use in providing a first shared computing environment of the first user that is available for use by other users of the multiple users;
• selecting, by the program execution service and for use in responding to the instructions from the first user, a first host computing node from a plurality of computing nodes that are provided by the program execution service for use by the multiple users;
• executing, by the program execution service and on behalf of the first user, the indicated one or more software programs on the first host computing node to provide the first shared computing environment for the first user;
• and
• while the providing of the first shared computing environment on the first host computing node for the first user continues,
• receiving, by the program execution service and from an additional user of the multiple users that is separate from the first user, a request to execute an additional program for the additional user using an indicated type of functionality that is available from the first shared computing environment;
• determining, by the program execution service and based on one or more specified criteria, whether to execute the additional program for the additional user on the first host computing node as part of the first shared computing environment or instead on a separate second host computing node of the plurality without any other programs of any other users;
• selecting, by the program execution service and based at least in part on the determining, to execute the additional program on the first host computing node as part of the first shared computing environment;
• and
• executing, by the program execution service, the additional program on the first host computing node, and accessing, under control of the executing additional program, the indicated type of functionality from the first shared computing environment of the first user on the first host computing node.