Systems and methods for pinning content in cache

An application server system, comprising:

• a processor-readable memory;
• and
• one or more processors;
• the memory including instructions that, when executed by the one or more processors, cause the processors to perform a method of operating an application server having one or more processors, volatile memory, and non-volatile memory, the method comprising:
• receiving a first request to execute a first application that is not currently loaded in the volatile memory of the application server, said first application being one of a first plurality of applications stored in the non-volatile memory of the application server;
• determining, in response to said receiving, that there is inadequate storage space in the volatile memory to store the first application;
• selecting from among a second plurality of applications stored in the volatile memory, an eviction target said selecting including
• determining whether any of said second plurality of applications are indicated as pinned to a cache, and
• in response to a determination that an application from among said second plurality of applications is indicated as pinned to the cache, excluding that application from selection as the eviction target;
• evicting from the volatile memory the eviction target;
• and
• loading and executing the first application in response to the first received request, and returning a result responsive to the first received request.

A non-transitory computer readable storage medium having instructions embodied thereon which, when executed by one or more processors, cause the one or more processors to perform a method of operating an application server having one or more processors, volatile memory, and non-volatile memory, the method comprising:

• receiving a first request to execute a first application that is not currently loaded in the volatile memory of the application server, said first application being one of a first plurality of applications stored in the non-volatile memory of the application server;
• determining, in response to said receiving, that there is inadequate storage space in the volatile memory to store the first application;
• selecting from among a second plurality of applications stored in the volatile memory, an eviction target said selecting including
• determining whether any of said second plurality of applications are indicated as pinned to a cache, and
• in response to a determination that an application from among said second plurality of applications is indicated as pinned to the cache, excluding that application from selection as the eviction target;
• evicting from the volatile memory the eviction target;
• and
• loading and executing the first application in response to the first received request, and returning a result responsive to the first received request.

A method of operating a plurality of application servers and an application master in an application execution system, the method comprising:

• at the application master:
• storing a plurality of applications in a library for distribution among the application servers;
• associating with each respective application a respective minimum cached instances requirement that specifies a number of instances of the respective application that are exempt from cache eviction;
• distributing applications from the library to the application servers for storage in a non-volatile memory in each of the application servers;
• monitoring the application servers to generate usage information for each of the applications in the library for a predefined period of time ending at a current time;
• and
• removing previously distributed applications from the non-volatile memory of respective application servers in accordance with the usage information for each of the applications in the library;
• wherein the distributing includes distributing a respective application to a respective number of the application servers determined by the application master in accordance with the usage information for each of the applications in the library and the minimum cached instances requirement for the respective application, and allocating instances of the respective application that are exempt from cache eviction among the application servers;
• and
• at a respective application server of the plurality of application servers:
• storing in non-volatile memory applications distributed to the application server;
• when a first respective application has an allocated minimum cached instances requirement greater than zero, loading an instance of the first respective application into volatile memory and designating the instance as exempt from cache eviction;
• and
• when a second respective application has an allocated minimum cached instances requirement equal to zero:
• loading the second respective application into volatile memory, executing the second respective application in response to a received request, and returning a result responsive to the request;
• and
• conditionally retaining the second respective application in volatile memory, for responding to a future request, when criteria, including at least predefined usage level criteria, are met by the second respective application, and otherwise removing the second respective application from volatile memory upon returning the result responsive to the request.