Abstract: Methods and systems consistent with this invention link a program module, which implements dynamic linkage to an external function and executes the external function. Such methods and systems replace a function name described in a header portion of a program module and a function name to be referred to by the program module with other names, and link functions having the same names as the replaced function names and executing the linked functions in place of an original function.

Abstract: A file system that reads a file, in response to a request from a user, from an external storage, transfers the read file to the user, and also stores a copy of the read file in a cache memory in consideration of the file's frequency in access so that the cache hit ratio may be improved. In response to a following request for the file stored in both the memory and the external storage, the file system transfers, to the user, the copy file stored in the memory instead of the file stored in the external storage in order to speed up the file access processing. The file system ejects a file having the least access count among the files stored in the memory when there is no space for storing the copy file in the memory.

Abstract: When the item appearance frequency count up section counts up the appearance frequency of an item in a shared memory space on the basis of transaction data, a count up log transfer section receives the count up log recorded by a count up log recording section and transfers it to other nodes. A count up log receiving section transfers the count up log transferred from each of the remaining nodes to a count up log reflecting section. The count up log reflecting section, which has received this count up log, reflects its contents in the appearance frequency of the corresponding item in the shared memory space.