Trace Indexing via Reverse Lookup Structures
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing time travel debuggers face performance issues during replay, as they often need to replay entire trace files to respond to inquiries, leading to slow response times and high resource utilization, making them unresponsive for debugging purposes.
Innovation Solution
Indexing trace files by breaking them into sections with key frames at points of interest and pre-calculating memory snapshots, along with generating reverse lookup data structures, to enable quick access to program state and reduce the need for large-scale replay.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing time travel debuggers replay entire trace files to respond to inquiries, then complete program state information is obtained, but response time becomes unacceptably slow and resource utilization becomes excessively high
Solution Approach 1:
The patent divides the trace file into multiple sections using key frames as delimiters. Each key frame marks a significant point in program execution (function boundaries, exception handlers, resource allocations). When a debugging inquiry is received, the system identifies the relevant section containing the inquiry point and replays only that section instead of the entire trace file, dramatically reducing response time while maintaining information completeness.
Solution Approach 2:
The patent performs preliminary processing during the tracing phase by recording key frames at predetermined points in the program execution. These key frames include pre-calculated program state information (register values, memory snapshots, call stack) at critical points. This preliminary capture of state information eliminates the need to replay entire trace sequences during debugging inquiries.
2Measurement precision
If existing time travel debuggers replay entire trace files to respond to inquiries, then accurate program state is obtained, but resource utilization becomes excessively high
Solution Approach 1:
By segmenting the trace file into manageable sections bounded by key frames, the system processes only the necessary subset of trace data for each debugging inquiry. This segmentation reduces CPU cycles, memory bandwidth consumption, and I/O operations required during replay, directly lowering resource utilization while preserving state accuracy through targeted replay of relevant sections.
Solution Approach 2:
The patent extracts and stores critical program state information at key frames during the preliminary tracing phase. These extracted state snapshots (including register values, memory contents, and call stack information) are saved in the trace file metadata. During debugging, this pre-extracted information is directly utilized without requiring full replay computation, significantly reducing runtime resource requirements.
3Productivity
If trace files are broken into sections with key frames, then replay responsiveness is improved, but trace file complexity increases
Solution Approach 1:
The trace file is segmented into sections using key frames as structural delimiters. Each key frame contains metadata identifying its position in the program execution and associated program state. This segmentation enables the debugger to quickly locate and replay only the necessary sections, improving responsiveness. The added complexity is managed through systematic organization of key frames at predictable program points (function boundaries, exceptions, resource operations).
Solution Approach 2:
Key frames serve as intermediary structures between the raw trace data and the debugging inquiry processing. Each key frame acts as an anchor point that facilitates efficient navigation and section identification. The key frame metadata (program counter, state snapshots) mediates between the inquiry parameters and the replay mechanism, simplifying the overall process despite the increased structural elements.
4Loss of time
If reverse lookup data structures are generated and inserted, then inquiry processing time is reduced, but trace file size and processing overhead increase
Solution Approach 1:
Reverse lookup data structures are generated during the preliminary indexing phase before debugging inquiries are processed. These structures pre-compute and store mappings from program identifiers (function names, variable names, memory addresses) to their locations and states in the trace file. When an inquiry is received, the system performs a quick lookup in these pre-built structures rather than searching through the entire trace, dramatically reducing inquiry processing time. The trade-off of increased trace file size is acceptable given the substantial performance improvement for interactive debugging.
Data Source
AI summary
Augmenting a trace with at least one reverse lookup data structure during indexing of the trace. A method includes receiving trace data observed during execution of executable entit(ies), and replaying a plurality of different sections of the trace data. The replay includes, for each trace section, executing a plurality of code instructions of the executable entit(ies) based on the section's portion of the trace data, and recording attribute(s) observed during the execution of the code instructions along with an identity of the trace section. At least one reverse lookup data structure is created. It associates each of at least a subset of the attributes observed during the replay of the plurality of trace sections with the identity of each trace section in which it was observed. This reverse lookup data structure is stored as part of one or more trace data streams.