c5a4068e84
* add state and callback pattern * add command and template-method pattern * add iterator pattern * add bridege and DI pattern * fix issue #1600 * add converter,proxy,visitor pattern * add caching,composite,delegation,dirty-flag,interpreter patterns * add dao and producer-consumer * add dto and provate class data pattern * fix #1646 png path problems * fix #1646 composite png path case problem * add abstract document pattern and version-number pattern * add ambassador pattern * add acyclic-visitor and api-gateway pattern * add abstract-factory pattern * add active-object pattern * add aggregator-microservices and arrange-act-assert pattern * update async-method-invocation pattern * add balking and business-delegate pattern * add bytecode and circuit-break pattern * update arrange/act/assert pattern problems * add csch pattern * add language code, correct pic path * #1805 update permalink Co-authored-by: Subhrodip Mohanta <subhrodipmohanta@gmail.com> Co-authored-by: Mike <admin@xiaod.info> Co-authored-by: Ilkka Seppälä <iluwatar@users.noreply.github.com>
22 lines
949 B
Markdown
22 lines
949 B
Markdown
---
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layout: pattern
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title: Double Checked Locking
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folder: double-checked-locking
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permalink: /patterns/double-checked-locking/
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categories: Idiom
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language: zh
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tags:
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- Performance
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---
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## 含义
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通过先测试锁定标准（"锁提示"）而不实际获取锁的方式来减少获取锁的开销。只有当锁定标准检查表明需要锁定时，才进行实际的锁定逻辑。
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## 类图
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## 适用场景
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在以下场景适合使用双重锁检查模式：
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* 在创建对象时有存在并发的访问。如单例模式中，你想创建同一个类的单个实例，如果存在两个或更多的线程对实例进行判空，仅仅检查该该实例是否为空可能是不够的。
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* 在一个方法上存在并发访问，该方法的行为是根据一些约束条件而改变，而这些约束条件在该方法中也会发生变化。 |