The performance of FileAppender significantly decreases under JDK21

[lushi516]

We tested FileAppender using JMH and found that compared to JDK1.8, the performance of JDK21 decreased by 30.5% (throughput decreased from 47.65 ops/ms to 33.08 ops/ms)

configuration

1. Laptop configuration: I5-1350P CPU, 32GB DDR5 5200 RAM, and Samsung MZVL4512HBLU-00BLL 512GB SSD.
2. Log4j2 version is 2.24.3.
3. Perform three performance tests and calculate the average value.

result

JDK Version	Score	gc.alloc.rate	gc.count
JDK 21.05	33.08 ops/ms	635.45 MB/sec	61.33
JDK 1.8.171	47.65 ops/ms	1,651.85 MB/sec	294

For detailed code and configuration parameters , please refer to: log4j2-perf-diff-jdk, Please refer to the complete test results: jmh-result.

[vy]

@zengzuo613, thanks so much for the report and the reproducer. Pinpointing performance issues are pretty time-consuming for maintainers. Could you also examine the test with a profiler and, hopefully, shed some light onto issue, please?