亚洲国产日韩欧美一区二区三区,精品亚洲国产成人av在线,国产99视频精品免视看7,99国产精品久久久久久久成人热,欧美日韩亚洲国产综合乱

Home Java javaTutorial How does node.next = node; in Java AQS source code help with garbage collection?

How does node.next = node; in Java AQS source code help with garbage collection?

Apr 19, 2025 pm 02:27 PM
Why

The GC optimization effect of cancelAcquire method in Java AQS source code: node.next = node;

When we are delving into the AQS (AbstractQueuedSynchronizer) source code in Java concurrency package, we often encounter a code in the cancelAcquire method: node.next = node; // help GC. This line of code comments suggest that it helps garbage collection, but its specific mechanism of action is not clear at a glance. Many developers may wonder: Why can simple self-circulating references improve GC efficiency? And is this really necessary?

The core issue of the article is to understand how node.next = node; this line of code helps garbage collection. Although the cancelAcquire method itself is not responsible for removing canceled nodes (actual removal is done by other methods such as acquireQueued), node.next = node; this operation plays a key role in the garbage collection process.

The key to the problem lies in cross-generational references. Even if a node has been removed from the AQS queue, making it logically unreachable, if the node has been promoted to the old age, it may still hold a reference to other nodes in the young generation (via next pointer). This cross-generation reference will prevent garbage collection of young generation nodes, even if these young generation nodes themselves are already unreachable. node.next = node; effectively cuts off the node's reference to other nodes of the younger generation, avoiding this cross-generation reference problem. Without this line of code, even if the logically unreachable nodes are in the old age, their next pointer points to the young generation nodes, which will hinder the young generation garbage collection, resulting in an increase in memory fragmentation and Full GC times.

It is worth noting that pointing next pointer to itself rather than null is because next pointing to null has a special meaning in AQS - indicating the tail of the queue. Although pointing next to null in theory can also achieve the purpose of cutting off references, this will change the structure of the queue and cause potential concurrency problems.

Additionally, AQS is a bidirectional queue, and ideally it should also handle prev pointers. However, in other methods of removing cancel nodes, similar treatments are not performed on the prev pointer, which implies that although node.next = node; can effectively alleviate the problem, there are still cross-generation reference problems caused by prev pointer, but the impact range is relatively small.

Finally, the article points out that in JDK17, node.next = node; line of code has been removed from the cancelAcquire method, which indicates that the latest JDK version may have solved this problem by improving the GC algorithm (such as better handling of cross-generation references), making this line of code no longer necessary. This also indirectly confirms that the function of this line of code is mainly to deal with the shortcomings of the previous version of the JVM garbage collection mechanism.

The above is the detailed content of How does node.next = node; in Java AQS source code help with garbage collection?. For more information, please follow other related articles on the PHP Chinese website!

Statement of this Website
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn

Hot AI Tools

Undress AI Tool

Undress AI Tool

Undress images for free

Undresser.AI Undress

Undresser.AI Undress

AI-powered app for creating realistic nude photos

AI Clothes Remover

AI Clothes Remover

Online AI tool for removing clothes from photos.

Clothoff.io

Clothoff.io

AI clothes remover

Video Face Swap

Video Face Swap

Swap faces in any video effortlessly with our completely free AI face swap tool!

Hot Tools

Notepad++7.3.1

Notepad++7.3.1

Easy-to-use and free code editor

SublimeText3 Chinese version

SublimeText3 Chinese version

Chinese version, very easy to use

Zend Studio 13.0.1

Zend Studio 13.0.1

Powerful PHP integrated development environment

Dreamweaver CS6

Dreamweaver CS6

Visual web development tools

SublimeText3 Mac version

SublimeText3 Mac version

God-level code editing software (SublimeText3)

How to withdraw coins on the ok exchange? Detailed tutorial on withdrawing coins on ok exchange How to withdraw coins on the ok exchange? Detailed tutorial on withdrawing coins on ok exchange Jul 03, 2025 pm 02:03 PM

?In today's increasingly popular digital asset trading, it is particularly important to understand how to safely and effectively withdraw your digital assets. As a world-renowned digital asset trading platform, ok exchange provides convenient currency withdrawal services. This tutorial will analyze in detail the steps of withdrawing coins on the ok exchange, things to note, and some common questions and answers to help users complete asset transfer smoothly and ensure asset security. Whether you are using ok exchange for withdrawals for the first time or want to further understand the withdrawal process, this article will provide you with clear and practical guidance.

What does grayscale digital market mean What does grayscale digital market mean Jul 01, 2025 pm 05:57 PM

Grayscale Digital Market refers to the overall performance of Grayscale Investment’s digital asset trust funds, and its core includes single asset trusts and compound funds. 1. "Grayscale" refers to Grayscale Investments, which has trust products such as GBTC and ETHE; 2. "Digital Market" refers to GDLC funds that track mainstream crypto assets in a narrow sense, and covers the overall performance of all trust products in Grayscale. Reasons to pay attention to the Grayscale Digital Market include: 1. Changes in its holdings reflect institutional investors' tendency to allocate cryptocurrencies; 2. Premium or discount fluctuations in trust products affect market sentiment; 3. As a compliance channel regulated by SEC, its trends have policy reference value.

AAVE In-depth Analysis: Why is it still the king of DeFi lending? AAVE In-depth Analysis: Why is it still the king of DeFi lending? Jul 01, 2025 pm 05:21 PM

The core of AAVE's ability to continue to lead the DeFi lending market lies in its comprehensive advantages such as technological iteration, innovative functions, security risk control, multi-chain strategy, and decentralized governance. 1. Technically, it continues to upgrade from V1 to V3 to achieve cross-chain lending and risk isolation; 2. Launch lightning loans, issue GHO stablecoins and lay out RWA real-world assets; 3. Ensure platform security through risk reserves, dynamic interest rates and governance audits; 4. Multi-chain deployment improves capital efficiency and liquidity network effects; 5. Transparent community governance, enhancing user trust and participation.

The popularity of the currency circle has returned, why do smart people have begun to quietly increase their positions? Look at the trend from the on-chain data and grasp the next round of wealth password! The popularity of the currency circle has returned, why do smart people have begun to quietly increase their positions? Look at the trend from the on-chain data and grasp the next round of wealth password! Jul 09, 2025 pm 08:30 PM

As the market conditions pick up, more and more smart investors have begun to quietly increase their positions in the currency circle. Many people are wondering what makes them take decisively when most people wait and see? This article will analyze current trends through on-chain data to help readers understand the logic of smart funds, so as to better grasp the next round of potential wealth growth opportunities.

Why is Dogecoin called 'meme coin'? What's the story? Why is Dogecoin called 'meme coin'? What's the story? Jul 02, 2025 pm 11:18 PM

Dogecoin, a unique existence in the cryptocurrency world, is often called "meme coin". Unlike many cryptocurrencies that pursue cutting-edge technology or solve practical problems, the origin and development of Dogecoin is closely linked to a specific Internet cultural phenomenon - that is "meme". Its birth itself is full of jokes and casualness, which sets the tone of light humor for its subsequent development. This unconventional beginning gives Dogecoin a unique, non-serious halo from the beginning.

Maxwell Hardfork of BNB chain: A new era of speed and efficiency Maxwell Hardfork of BNB chain: A new era of speed and efficiency Jul 02, 2025 pm 08:24 PM

Explore how Maxwell Hardfork can reshape BNB chains by shortening block time and improving performance, helping it make its mark in the DeFi field. BNB chain has caused a stir with its latest upgrade - Maxwell Hardfork. This is not an ordinary update, but a major leap, aiming to completely improve the user experience and open up new possibilities for developers. Let's dive into why this upgrade is so eye-catching. What is a Maxwell hard fork? Maxwell Hardfork is a disruptive change in the BNB chain. The upgrade cuts the block time to just 0.75 seconds, meaning nearly instant transaction confirmation, smoother DeFi settlement and a virtually no latency interactive experience in gaming DApps.

Get rich overnight? These soaring coins are changing the market structure! Get rich overnight? These soaring coins are changing the market structure! Jul 01, 2025 pm 05:30 PM

Recently, multiple currencies in the cryptocurrency market have soared. Notcoin (NOT), Pepe (PEPE), Brett (BRETT), Render (RNDR), and Ondo (ONDO) have achieved significant increases due to social blockchain, community consensus, Base chain ecology, AI computing power demand, institutional entry and other factors; its upward logic includes strong narrative support, low market value and high volatility, exchange online effect, and community and celebrity influence; the surge in coins drives funds to flow to altcoins, the rise of new public chains, the accelerated layout of institutions and the intensification of retail FOMO sentiment; ordinary people should pay attention to strong tracks, ambush potential coins, and use new effects, while being wary of high volatility risks, Rug Pull and out of control of positions.

What does Bitcoin halving mean? What impact will it have on price? What does Bitcoin halving mean? What impact will it have on price? Jul 01, 2025 am 09:51 AM

Bitcoin is a decentralized digital currency whose issuance mechanism is designed to have strict upper limits. This design ensures that the total amount of Bitcoin is limited, about 21 million. New Bitcoins are generated through the “mining” process where miners verify transactions and package them into the blockchain by solving complex computing problems. As a reward, the miners will receive a certain amount of new Bitcoins as well as transaction fees. This block reward is one of the important sources of Bitcoin supply.

See all articles