Patent US 6,317,869

Many programming languages utilize reference pointers in computer code. Furthermore, some of these programming languages perform memory management in the form of garbage collection. Once such language is Java. During the execution of a garbage collection routine, the computer may need to locate all the variables containing reference values. The present invention introduces a method for run-time tracking of object references in computer code and determining which variables contain references to objects at garbage collection sites. The method of the present invention first creates a bit vector in memory. The bit vector is then initialized. Second, each variable declared in the computer program that may be used to store a reference value is assigned a unique bit within this bit vector. Each bit is maintained to indicate whether the variable it is assigned to is currently storing a reference value. Specifically, when a variable is assigned a reference value, the corresponding bit in the bit vector is set. When a variable is assigned a non-reference value, the corresponding bit in the bit vector is cleared.