空db flushdb需要2s，需要优化

[chejinge]

Is this a regression?

Yes

Description

Please provide a link to a minimal reproduction of the bug

No response

Screenshots or videos

空db flushdb用了2s的时间，这样肯定会影响主从复制的一致性测试

Please provide the version you discovered this bug in (check about page for version information)

No response

Anything else?

No response