Conservative Garbage Collection with Encoded Pointers for Memory Leak Detection
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Solution Overview
Problem
Conventional garbage collection techniques fail to account for arbitrary pointer synthesis in C/C++ languages, leading to inadequate memory management and memory leak detection, as they assume all pointers are present in program memory at scan time, neglecting pointers generated during execution through pointer arithmetic.
Innovation Solution
The implementation of conservative garbage collection techniques that include creating an initial root set of pointers, marking referred objects, and using encoded pointers to filter and re-mark objects, excluding red-marked non-live objects, thereby identifying memory leaks and ensuring memory access protection within the allocated memory bounds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional garbage collection techniques are used that scan program memory for pointers, then the collection process is simple to implement, but it fails to detect pointers synthesized during execution through pointer arithmetic, leading to memory leaks
Solution Approach 1:
The system performs preliminary encoding of all pointer values with metadata indicating their validity status before garbage collection. This preliminary action allows the garbage collector to efficiently identify and track pointers that are synthesized during execution, without requiring complex analysis during the collection process itself. The encoding is done in advance, enabling accurate detection while maintaining relatively simple collection logic.
Solution Approach 2:
The patent introduces an intermediary encoding layer between the raw pointer values and the garbage collection process. This encoding acts as a mediator that carries additional information about pointer validity and origin, allowing the garbage collector to distinguish between legitimate pointers and those synthesized through pointer arithmetic without requiring the collector itself to be complex. The intermediary encoding bridges the gap between simple collection and accurate detection.
2Reliability
If the entire program memory is inspected for pointers, then all possible pointers are captured, but the inspection time and computational resources increase significantly
Solution Approach 1:
The system extracts and isolates only the relevant portion of memory that contains valid pointers by using the encoded metadata to identify live objects. Instead of inspecting the entire program memory, the garbage collector extracts and processes only those memory regions that contain pointers with valid encoding, significantly reducing inspection time while maintaining completeness for all actual pointers.
Solution Approach 2:
By performing preliminary encoding of pointers with validity information, the system prepares the data structure in advance so that during garbage collection, only valid pointer regions need to be inspected. This preliminary action filters out invalid or synthesized pointers before the inspection process begins, reducing the scope of memory that needs to be examined while ensuring all legitimate pointers are captured.
3Productivity
If conservative garbage collection is performed without excluding red-marked objects, then the process is simpler, but it may incorrectly identify live objects as memory leaks
Solution Approach 1:
The system implements a feedback mechanism through the two-phase marking process where the results of the first marking phase inform the second phase. Red-marked objects identified in the first phase provide feedback that prevents their incorrect identification as memory leaks in the second phase. This feedback loop ensures accurate differentiation between live and dead objects while maintaining efficient collection processes.
Solution Approach 2:
The patent employs dynamic object status tracking through multiple marking phases, where objects can transition between different marking states (white, gray, black, red). This dynamic approach allows the system to adaptively determine object liveness based on reachability analysis, improving accuracy in memory leak identification while maintaining efficiency through structured state transitions rather than static analysis.
Data Source
AI summary
A method of memory management can include creating an initial root set of pointers for a program during execution of the program and performing a marking process by iteratively marking referred objects of each pointer of the root set and expanding the root set with filtered, encoded pointers. The method also can include identifying each non-live object for any marked object as red-marked and performing, using a processor, a re-marking process on the root set in which red-marked objects are excluded. Each object of the root set not marked can be designated as including a memory leak.