Garbage Collection Queue Heavy-Weight Task Positioning

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Solution Overview

Problem

Load balancing work stealing in garbage collection systems is computationally expensive and inefficient due to frequent task stealing between threads, leading to performance degradation.

Innovation Solution

Positioning heavyweight tasks at the top of the garbage collection owner queue to delay subsequent steal attempts by thief threads, thereby reducing the frequency of work stealing and improving efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If work stealing is frequently performed to balance load between threads, then load balancing effectiveness is improved, but computational overhead and system performance deteriorate

Engineering Contradiction:
Improveload balancing effectivenessVSAvoidcomputational overhead
Core Design Contradiction:
ProductivityVSLoss of energy

Solution Approach 1:

The system performs preliminary classification of tasks into heavyweight and lightweight categories before they enter the owner queue. By pre-positioning heavyweight tasks at the queue head through classification and prioritization mechanisms, the system prepares the queue structure in advance to minimize future steal attempts, reducing the computational overhead of frequent load balancing operations.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system applies different handling strategies to different parts of the task queue based on task characteristics. Heavyweight tasks are given special treatment by being positioned at the queue head, while lightweight tasks remain in the standard queue structure. This local differentiation optimizes the balance between load balancing effectiveness and computational overhead by applying prioritization only where it provides maximum benefit.

Inventive Principle:
Principle #3Local quality

2Productivity

If thief threads attempt to steal tasks from owner queues, then workload distribution is improved, but the frequency of steal attempts increases computational costs

Engineering Contradiction:
Improveworkload distributionVSAvoidtime between steal attempts
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

The system preliminarily structures the owner queue by classifying and positioning heavyweight tasks at the head before any steal attempts occur. This preliminary arrangement ensures that when thief threads do attempt to steal work, they encounter computationally intensive tasks that keep them occupied for longer periods, thereby extending the time between subsequent steal attempts and reducing the overall frequency of load balancing operations.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system changes the parameter of task positioning within the queue based on task characteristics. By dynamically adjusting the position of heavyweight tasks to the queue head while maintaining standard positioning for lightweight tasks, the system modifies the temporal parameters of steal attempt frequency, extending the interval between steals and reducing computational overhead.

Inventive Principle:
Principle #35Parameter changes

3Loss of energy

If heavyweight tasks are positioned at the top of the owner queue, then steal attempt frequency is reduced, but queue management complexity increases

Engineering Contradiction:
Improvecomputational costs of work stealingVSAvoidqueue management complexity
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The system performs preliminary classification of tasks into heavyweight and lightweight categories during task creation or submission. By establishing classification criteria and prioritization rules in advance, the system automates the queue management process, reducing the complexity of real-time queue manipulation while maintaining the benefit of extended steal attempt intervals.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The queue management system uses self-service mechanisms where tasks essentially prioritize themselves through classification tags or metadata that indicate their computational weight. This self-service approach reduces the need for complex external queue management logic, as the prioritization is inherent in the task structure itself, thereby reducing overall system complexity while maintaining reduced steal frequency.

Inventive Principle:
Principle #25Self-service

Data Source

PatentUS11645200B2Reducing load balancing work stealing
Publication Date: 2023.05.09 INTERNATIONAL BUSINESS MACHINE CORPORATION
  • US11645200B2 patent drawing
  • US11645200B2 patent drawing
  • US11645200B2 patent drawing

AI summary

Embodiments are disclosed for a method. The method includes determining that a thief thread attempted a work steal from a garbage collection (GC) owner queue. Additionally, the method includes determining that a number of tasks in the GC owner queue meets a predetermined threshold. Further, the method includes determining that the GC owner queue comprises a heavy-weight task. The method also includes moving the heavy-weight task to a top position of the GC owner queue.