Java Classpath Matching via Hash Code Cache
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Solution Overview
Problem
Current systems for classpath matching in shared classes systems are resource-intensive, particularly when multiple JVMs share classes, leading to costly string-matching operations, especially with long classpaths, which hampers performance and efficiency in class-loading.
Innovation Solution
A cooperative class cache system that identifies and records matching classpaths once, using a unique key generated from the classloader ID and classpath entry-count, allowing for efficient equivalence checking and avoiding repeated comparisons by maintaining a local array of identified classpaths, ensuring byte-for-byte comparison only when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a shared class cache is used to store classes shared between multiple JVMs, then memory duplication is reduced, but resource-intensive string-matching operations are required to validate classpath equivalence
Solution Approach 1:
The system pre-calculates and stores hash codes for each classpath entry when classes are initially loaded into the shared cache. This preliminary action eliminates the need for expensive string-matching operations during subsequent classpath validation, as the hash codes can be quickly compared instead of performing byte-for-byte string comparisons.
Solution Approach 2:
The invention replaces the mechanical string-matching process with a hash-based comparison mechanism. Instead of performing sequential byte comparisons on classpath strings, the system uses hash code generation and comparison, which is computationally much more efficient and reduces the resource intensity of classpath validation operations.
2Measurement precision
If classpath validation is performed by comparing entire classpath strings, then accuracy is ensured, but performance deteriorates with long classpaths
Solution Approach 1:
The system substitutes expensive string comparison operations with efficient hash code comparison. The hash code is generated from the entire classpath string, ensuring that the full path is considered for accuracy, while the comparison itself is performed on fixed-size hash values rather than variable-length strings, dramatically improving performance.
Solution Approach 2:
The invention changes the parameter being compared from the original classpath string to a derived hash code parameter. This transformation maintains the uniqueness and accuracy properties of the original classpath while enabling much faster comparison operations, as hash codes are fixed-size integer representations regardless of the original string length.
3Adaptability or versatility
If a shared class cache allows cooperative sharing without restrictions, then system flexibility is improved, but classpath matching complexity increases
Solution Approach 1:
The system replaces complex string-matching logic with simple hash code comparison operations. This substitution maintains the ability to handle diverse classpath configurations in the shared cache while simplifying the matching process to basic hash equality checks, reducing the algorithmic complexity of classpath validation.
Solution Approach 2:
The hash code mechanism serves multiple functions: it ensures accurate classpath matching, enables fast comparison operations, and works universally across different classpath configurations and JVM instances. This universal approach allows the shared cache to accommodate various sharing scenarios without increasing matching complexity.
Data Source
AI summary
A system 300 and method for fast matching of JAVA classpaths in a shared classes JVM system by identifying classpaths of loaded classes and storing a local array (110, 210) of identified classpaths in order to avoid checking on a subsequent class load for a particular JVM. This allows dramatic speeding up of class-loading in cases where multiple JVMs are running similar applications.