Learn how to use pattern-matching features in your Java programs, including pattern matching with switch statements, when clauses, sealed classes, and a preview of primitive type pattern matching ...

分段锁的改进： Java 8中的ConcurrentHashMap取消了分段锁机制，采用更细粒度的锁来实现并发控制。 ConcurrentHashMap的数据结构被分割成多个独立的部分，每个部分维护自己的锁。 通过细粒度的锁机制，使得读操作可以并发执行，提高了并发性能。 ConcurrentHashMap机构 总结： ...

Under recursive scene of caffeine, we are experiencing deadlocks in caffeine version 2.9.0 (java version is 1.8.0_152). threaddump: at java.util.concurrent.ConcurrentHashMap.compute (ConcurrentHashMap ...

Some exceptions in Java must be handled in the developer's code. Other exceptions can occur without any exception handling semantics at all. When an exception must be handled with try-and-catch ...

Don't let the occurrence of a RuntimeException in Java bring your code to a standstill. Here are 10 examples of how to avoid runtime exceptions in Java.

We just tried to upgrade a relatively large application to spring boot 2.3.0.RC1 which includes micrometer 1.5.0. The application relies on redis and we have included various metrics for lettuce ...

ConcurrentHashMap是由Segment数组结构和HashEntry数组结构组成。 Segment是一种可重入锁ReentrantLock，在ConcurrentHashMap里扮演锁的角色，HashEntry则用于存储键值对数据。

在Java 7中ConcurrentHashMap对每个Segment单独计数，想要得到总数就需要获得所有Segment的锁，然后进行统计。 由于Java 8抛弃了Segment，显然是不能再这样做了，而且这种方法虽然简单准确但也舍弃了性能。