让找问题根因， 

找到一个代码缺陷
The remaining causal boundary

The capture also records 27,295 legitimate empty-queue output attempts 
during this minute. Those can mark application limitation without hitting 
the defective predicate. The logged cf_app_limited gauge is different from BBR2’s private per-packet sampler flag; treating them as 
interchangeable would manufacture proof. 
Therefore, I have establishe...