International Business Machines Corporation

John Duimovich

Trent Gray-Donald

Peter Duncan Shipton

Andrew Russell Low

Graeme Johnson

Graham Alan Chapman

Ryan Andrew Sciampacone

Berthold Martin Lebert

Kim Clohessy

Peter Wiebe Burka

Patrick James Mueller

Ryan Andrew Sciampancone

A runtime-resource management method, system, and product for managing resources available to application components in a portable device. The method, system, and product provide for loading one or more new application components into a portable device only if maximum runtime resources required by the one or more new application components are available in the portable device assuming loaded application components within the device are using the maximum runtime resources reserved by the loaded application components, reserving maximum runtime resources required by application components when application components are loaded into the portable device, and running loaded application components using only the runtime resources reserved for the loaded application components.

Runtime-resource management

The stack mapper of the present invention seeks to determine the shape of the stack at a given program counter. This is accomplished by locating all start points possible for a given method, that is, at all of the entry points for the method and all of the exception entry points, and trying to find a path from the beginning of the method to the program counter in question. The mapper first tries to locate a linear path from the beginning of the method, and then iteratively processes the sequence of bytes at each branch until the destination program counter is reached. Once the path is found, a simulation is run of the stack through that path, which is used as the virtual stack for the purposes of the garbage collector.

Mapping a stack in a stack machine environment

In typical Java and other interpreted programming language environments, the code is stored in ROM in a semi-processed state, .class files containing byte codes. When the device is turned on, a virtual machine resolves references and links the .class file in RAM to permit desired applications to be run. In the invention, the .class files are further pre-processed to select the data which will not change or require updating. This data is packaged into memory image files containing internal data pre-linking this data. The memory image files are stored in ROM and are accessible from ROM by the virtual machine at runtime. Only elements that will be updated, such as the objects themselves, must be instantiated in RAM at runtime. This reduces the amount of RAM needed to run the application. In an environment with memory constraints, the reduction in RAM requirements permits more RAM to be made available for application use.

Packaging memory image files

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Ottawa, Canada

John Duimovich