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Addressing Race Condition Problem in a Graph Based Visual Language


Kamal Z. Zamli, Nor Ashidi Mat Isa


Vol. 7  No. 7  pp. 146-152


Graph based visual languages are typically based on nodes, directed arcs and sub-graphs. Nodes represent function or actions, arcs carry data or control-flow signals, and sub-graphs provide abstraction and modularization. Operations in graphs follow a firing rule which defines the conditions under which execution of node occurs. In the control flow based model, the firing rule is based solely on the availability of the control-flow signals on the node’s input arcs. In the data flow based model, the firing rule is based on the availability of the required data on the node’s input arcs. This paper discusses our partial evaluation of a domain specific graph based visual language, called VRPML utilizing the well-known ISPW-6 benchmark problem as a case study. The focus of the evaluation is on the firing rule. Due to its control flow based firing rule, we observe that VRPML suffers from race condition problem, that is, two or more control-flow signals can inadvertently and erroneously compete to enable a particular activity node. This paper outlines our proposal to address the problem and enhance the language syntax and semantics.


Visual Language, VRPML