spring中cache注解中加上表达式会变慢！

在老外的两篇博文中&＃xff0c;https://plumbr.io/blog/performance-blog/more-about-spring-cache-performance
&＃xff0c;https://plumbr.io/blog/performance-blog/spring-cache-profiling

分别讲解了&＃xff0c;在&＃64;cache注解中&＃xff0c;使用参数速度变慢&＃xff08;通过JMH)基准测试工具测试。

不使用参数&＃xff1a;

&＃64;Cacheable("time")
public long annotationBased(String dummy) {return System.currentTimeMillis();
}

public long manual(String dummy) {Cache.ValueWrapper valueWrapper &＃61; cache.get(dummy);long result;if (valueWrapper &＃61;&＃61; null) {result &＃61; System.currentTimeMillis();cache.put(dummy, result);} else {result &＃61; (long) valueWrapper.get();}return result;
}
JMH结果&＃xff1a;

Benchmark Mode Cnt Score Error Units

CacheBenchmark.annotationBased avgt 5 245.960 ± 27.749 ns/op

CacheBenchmark.manual avgt 5 16.696 ± 0.496 ns/op

CacheBenchmark.nocache avgt 5 44.586 ± 9.091 ns/op
可以看到&＃xff0c;avgt是平均执行每次操作的耗费时间长短&＃xff0c;手工的快&＃xff1b;

再看注解中有参数的&＃xff1a;

&＃64;Cacheable(value &＃61; "time", key &＃61; "#p0.concat(#p1)")
public long annotationWithSpel(String dummy1, String dummy2) {return System.currentTimeMillis();
}
&＃64;Cacheable(value &＃61; "time")
public long annotationBased(String dummy1, String dummy2) {return System.currentTimeMillis();
}
JMH测试结果&＃xff1a;

Benchmark                       Mode Cnt Score Error Units
CacheBenchmark.annotationBased  avgt 5 271.975 ± 11.586 ns/op
CacheBenchmark.spel             avgt 5 1196.744 ± 93.765 ns/op
CacheBenchmark.manual           avgt 5 16.325 ± 0.856 ns/op
CacheBenchmark.nocache          avgt 5 40.142 ± 4.012 ns/op