The ARINC-653 standard architecture for flight software specifies an application executive (APEX) which provides an application programming interface and defines a hierarchical framework which provides health management for error detection and recovery. In every partition of the architecture, however, processes may have to deal with asynchronous real-time signals from peripheral devices or may communicate with other processes through blackboards or buffers. This configuration may lead programs into concurrency faults such as unintended race conditions which are common and difficult to be removed by testing. Unfortunately, existing tools for reporting concurrency faults in applications that use concurrent signal handlers can neither represent the complex interactions between an ARINC-653 application and its error handlers nor provide effective means for understanding the dynamic behavior of concurrent signal handlers involved into data races. Thus, this paper presents an intuitive tool that visualizes the partial ordering of runtime events to detect concurrency faults in an ARINC-653 application that uses concurrent signal handlers. It uses vertically parallel arrows with different colors to capture the logical concurrency between the application, its error handlers and concurrent signal handlers, and materializes synchronization operations with differently colored horizontal arrows. Our visualization tool allows at a glance, to visually detect data races and provides a great understanding of the program internal for an easy debugging process.
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