The Weaves Reconfigurable Programming Framework

Abstract

This research proposes a language independent intra-process framework for object based composition of unmodified code modules. Intuitively, the two major programming models, threads and processes, can be considered as extremes along a sharing axis. Multiple threads through a process share all global state, whereas instances of a process (or independent processes) share no global state. Weaves provide the generalized framework that allows arbitrary (selective) sharing of state between multiple control flows through a process. The Weaves framework supports multiple independent components in a single process, with flexible state sharing and scheduling, all of which is achieved without requiring any modification to existing code bases. Furthermore, the framework allows dynamic instantiation of code modules and control flows through them. In effect, weaves create intra-process modules (similar to objects in OOP) from code written in any language. The Weaves paradigm allows objects to be arbitrarily shared, it is a true superset of both processes as well as threads, with code sharing and fast context switching time similar to threads. Weaves does not require any special support from either the language or application code, practically any code can be weaved. Weaves also include support for fast automatic checkpointing and recovery with no application support. This paper presents the elements of the Weaves framework and results from our implementation that works by reverse-analyzing source-code independent ELF object files. The current implementation has been validated over Sweep3D, a benchmark for 3D discrete ordinates neutron transport [Koch et al., 1992], and a user-level port of the Linux 2.4 family kernel TCP/IP protocol stack.