Event-based debugging system for a parallel object-oriented language A-NETL

Abstract

Debugging of parallel programs is generally very difficult to undertake since the execution of programs is nondeterministic and nonrepeatable. Considering a parallel object-oriented language, this paper proposes a method of preserving the repeatability of the order of execution in a replay by defining a logic time in terms of events in the message communication system and state transitions, and by representing the execution history of events. A debugger that mainly uses a two-dimensional (2-D) representation and replay debugging has been designed based on the proposed method. A high-performance system has been constructed based on the design. The debugger functions are distributed between a host workstation and multicomputer nodes, and between local OS on nodes and in firmware so that a high-performance system has been realized. The experiments show that the method is successful for practical applications; the time and space overhead of event recording is 0.04 ms (mean value) and 35 B per event, respectively; the display of 16 objects for one logical time is 0.94 s; and the overhead for a breakpoint is 3.1 ms per point. © 1998 Scripta Technica, Syst Comp Jpn, 28(11): 53–63, 1997