Dynamic Instrumentation via Synchronization Mechanism
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Solution Overview
Problem
Current profiling systems for computer programs require navigating decision trees to switch between instrument functionalities, which impacts execution time and can be resource-intensive, especially in virtual machines with size restrictions.
Innovation Solution
The use of a synchronization mechanism, such as a volatile or synchronized field, allows for dynamic updating of instrumentation without a decision tree structure, enabling atomic and thread-visible updates, and the implementation of static instrumentation calls to reduce footprint and allow larger routines to be instrumented.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple instrument routines are inserted into target program routines to provide different profiling functionality, then instrument versatility is improved, but execution time increases due to decision tree navigation
Solution Approach 1:
The patent applies dynamics by making the instrument selection process dynamic rather than static. Instead of navigating a decision tree at runtime, the system dynamically updates a synchronization field (volatile or synchronized) that directly references the current instrument implementation. This allows the target program to directly call the appropriate instrument routine without conditional logic, resolving the contradiction between versatility and execution time.
Solution Approach 2:
The synchronization field acts as an intermediary between the target program and multiple instrument routines. Rather than the target program containing decision logic to select among multiple instruments, the synchronization field mediates by holding a reference to the currently selected instrument, simplifying the call path while maintaining access to multiple instrument functionalities.
2Reliability
If large routines are instrumented with multiple or large instrument calls, then profiling coverage is improved, but virtual machine routine size restrictions are violated
Solution Approach 1:
The patent extracts the instrument selection logic from within the target program routines. By removing the decision tree structure from the instrumented code and placing it in the external instrumentation system (which updates the synchronization field), the routine size overhead is minimized. Only a single lightweight call to the instrument routine remains in the target code, well within virtual machine size restrictions.
Solution Approach 2:
A single instrument routine call serves multiple profiling purposes through the synchronization field mechanism. The same instrument call infrastructure supports different profiling functionalities by changing which instrument implementation is referenced in the synchronization field, eliminating the need for multiple separate instrument call paths in the target code.
Data Source
AI summary
Systems and methods for using a synchronization mechanism to dynamically update instrumentation during program execution are described herein. Using the synchronization mechanism, a decision tree structure of instruments can be avoided, saving processing resources. The synchronization mechanism can be a field or the like that is declared using a synchronization primitive. For example, the synchronization primitive can be a volatile or synchronized keyword in some programming languages. The field can refer to a currently-selected instrument implementation, thereby avoiding using a decision-tree structure to find a desired instrument implementation.