Foreign Memory Session Hierarchies to Prevent Premature Deallocation
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Solution Overview
Problem
In computer systems, managing temporal dependencies between sets of foreign resources is crucial to prevent deallocation of resources still in use, which can lead to unpredictable system behavior such as data corruption and crashes, as the garbage collector does not manage these resources.
Innovation Solution
A runtime environment manages temporal dependencies by allocating foreign resources to a memory session and ensuring that the parent memory session remains open as long as any descendant sessions have access, using a directed acyclic graph to track parent-child relationships and maintain reference counters to prevent premature deallocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the garbage collector manages foreign resources, then memory management is simplified, but foreign resources cannot be properly tracked and deallocated when still in use
Solution Approach 1:
The patent segments memory management into two distinct systems: the garbage collector manages the Java heap (on-heap resources), while a separate foreign resource manager tracks off-heap resources. This segmentation allows each system to specialize in managing its respective resource type without interfering with the other, resolving the contradiction between simplified GC operation and reliable foreign resource tracking.
Solution Approach 2:
The patent introduces a foreign resource manager as an intermediary between the garbage collector and foreign resources. This mediator tracks usage of off-heap resources and coordinates their deallocation, ensuring that foreign resources are not deallocated while still in use. The intermediary handles the complexity of foreign resource tracking while allowing the GC to continue managing heap resources efficiently.
2Quantity of substance
If foreign resources are deallocated when no longer in use, then memory efficiency is improved, but premature deallocation causes data corruption and crashes
Solution Approach 1:
The patent implements a feedback mechanism where the foreign resource manager continuously monitors usage of off-heap resources through reference counters. When a resource is allocated, the counter is incremented; when deallocated, it is decremented. The manager uses this feedback to determine when a resource can be safely deallocated from the operating system, preventing both premature deallocation and memory leaks while maintaining system stability.
Solution Approach 2:
The patent performs preliminary tracking of foreign resource usage before deallocation occurs. By maintaining reference counters that track the number of active references to foreign resources, the system prepares information about resource usage state in advance. This preliminary action allows the system to make informed decisions about when to deallocate resources, ensuring safety before actual deallocation happens.
3Reliability
If reference counters track all foreign resource usage, then premature deallocation is prevented, but tracking overhead increases
Solution Approach 1:
The patent applies local quality by tracking reference counts at specific locations (foreign resource entries in the foreign resource manager) rather than implementing a comprehensive system-wide tracking mechanism. Each foreign resource has its own reference counter that tracks only the relevant usage information needed for safe deallocation. This localized tracking reduces overall system complexity while maintaining reliable resource management.
Data Source
AI summary
Techniques for managing temporal dependencies between sets of foreign resources are disclosed, including: allocating, in a runtime environment, a segment of foreign memory to a first memory session, the runtime environment being configured to use a garbage collector to manage memory in a heap, and the foreign memory including off-heap memory that is not managed by the garbage collector; opening, in the runtime environment, a second memory session that descends from the first memory session; while the second memory session is open, encountering a request to close the first memory session; responsive to encountering the request to close the first memory session, determining that the first memory session has at least one open descendant memory session; responsive to determining that the first memory session has at least one open descendant memory session, declining the request to close the first memory session.