Replayable Execution Trace Diffing for Debugging Rare Software Behaviors
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Solution Overview
Problem
Identifying and debugging undesired software behaviors in complex applications is challenging due to their rarity, randomness, and the difficulty in reproducing them, leading to time-consuming and resource-intensive processes for developers.
Innovation Solution
A method and system for diffing replayable execution traces, which groups sequences of related executable instructions and compares them based on attributes to determine equivalence, even if individual instructions differ, allowing for efficient comparison of execution traces from different binaries, compiler versions, and processor architectures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If execution traces are compared at the individual instruction level, then measurement precision is improved, but computational complexity increases significantly
Solution Approach 1:
The patent segments the execution trace into multiple hierarchical levels: instruction-level segments, basic block segments, function segments, and module segments. This segmentation allows comparison to be performed at different granularities, enabling precise comparison when needed while reducing computational complexity by allowing higher-level summaries for initial comparison. The hierarchical structure permits the system to start with coarse-grained module-level comparison and drill down to instruction-level comparison only where differences are detected.
Solution Approach 2:
The patent introduces a temporal dimension by comparing not only the structural content of execution traces but also their timing characteristics. Execution traces are represented with timestamp information, allowing the system to compare both what instructions were executed and when they were executed. This multi-dimensional comparison approach enriches the analysis capability while maintaining computational feasibility through selective detailed comparison.
2Measurement precision
If execution traces capture vast amounts of information at high instruction rates, then measurement precision is improved, but data processing complexity increases
Solution Approach 1:
The patent divides the vast execution trace data into manageable segments organized hierarchically from fine-grained instruction levels to coarse-grained module levels. Each segment can be processed and compared independently, reducing the complexity of handling the entire trace at once. The segmentation enables progressive refinement where only relevant segments require detailed processing.
Solution Approach 2:
The patent applies partial action by performing detailed comparison only on segments that are suspected to contain differences, rather than analyzing every instruction in every trace. The system uses higher-level summaries and metadata to identify regions of interest, then applies detailed instruction-level analysis only to those specific regions, significantly reducing overall processing complexity while maintaining precision where needed.
3Ease of operation
If conventional debugging tools operate on live forward-executing code, then ease of operation is maintained, but ability to analyze rare and random behaviors is reduced
Solution Approach 1:
The patent implements preliminary action by recording and capturing execution traces during normal program operation before any debugging analysis is performed. These traces are stored with complete fidelity including instruction-level detail and timing information. This preliminary capture allows subsequent offline analysis of rare and random behaviors without interfering with the actual program execution, enabling detection of behaviors that might not be reproducible through conventional live debugging.
Solution Approach 2:
The patent creates a copy of the execution trace data that can be analyzed independently of the live program. The traced execution is captured and stored as a separate data structure that can be replayed, compared, and analyzed without affecting the original program's operation. This copying approach preserves the ability to analyze rare behaviors while maintaining ease of operation for the original program and debugger.
Data Source
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AI summary
Diffing a subject replayable trace against a plurality of comparison replayable traces includes identifying a set of mappings among the comparison replayable traces, each identifying corresponding comparison sections of consecutive instructions recorded in the comparison replayable traces that execute equivalently. A plurality of distinct comparison sections are identified within the comparison replayable traces. Each of a plurality of subject sections within the subject trace is compared against distinct comparison section(s) to determine a comparison status for each subject section, including whether each subject section is (i) equal to at least one corresponding distinct comparison section, or (ii) different than the distinct comparison sections. The determined comparison status of at least one particular subject section with respect at least one particular corresponding distinct comparison section is applied to each additional comparison section to which the at least one particular distinct comparison section is mapped in the set of mappings.