Dynamic program updating in a distributed computer system

The authors present an approach to update a computer program dynamically (i.e., while it is executing). Such an approach is important in applications where the cost of stopping and restarting the program makes doing so impractical. The approach works with programs written in procedural languages such as Pascal, C, and Fortran, and it scales to a distributed computer system. The authors assume that computer programs are written in a top-down manner consistent with good software engineering practices. The also assume that the computer system logically provides a networkwide sparse virtual address space. The approach uses these assumptions to update computer programs in a distributed system with minimum interruption to the running program. An overview of the design and implementation of a prototype updating system is discussed, and future work is described