Spring 缓存番石榴 TTL 配置的奇怪行为

Question

我有以下 spring 缓存配置：

spring.cache.guava.spec: expireAfterWrite=1s

那我测试一下:

@Test
public void test_not_work() {
  callCachedMethod(..);
  sleep(2s);
  callCachedMethod(..);

  expect("real method called TWO times"); 
  // because cache should be expired after 1s
  // It DOESN'T work, real method only called once
}

@Test
public void test_works() {
  callCachedMethod(..);
  sleep(2s);
  callCachedMethod(..);
  sleep(2s);
  callCachedMethod(..);

  expect("real method called THREE times"); 
  // because cache should be expired after 1s
  // IT WORKS!!
}

谁能解释一下？

Answer 1

这是因为 Guava 无法确保在超时值到期时自动驱逐这些值。

根据其文档 here：

Caches built with CacheBuilder do not perform cleanup and evict values "automatically," or instantly after a value expires, or anything of the sort. Instead, it performs small amounts of maintenance during write operations, or during occasional read operations if writes are rare.

Spring 缓存番石榴 TTL 配置的奇怪行为

Strange Behavior for Spring cache guava TTL config

spring

spring-boot

guava

spring-cache

google-guava-cache