bneradt commented on issue #7380:
URL: https://github.com/apache/trafficserver/issues/7380#issuecomment-749740797


   Considering @masaori335 's observations, I've been looking at the code and 
reviewing the negative caching patch and I do notice a change that the negative 
caching fix did that I didn't anticipate. Here was the code that @masaori335 
referenced before fix:
   
   
https://github.com/apache/trafficserver/blob/f3647619921ada5214b78d6ddb594a10fbc99a15/proxy/http/HttpTransact.cc#L4505
   
   Before the patch, the value of `negative_caching` was true iff the response 
was cacheable because of negative caching configuration. That is, a 200 
response would not cause it to be true: only negative status codes that were 
considered cacheable because negative caching was enabled would have caused 
negative_caching to be evaluated to true. With the patch, the `cacheable` 
variable was changed to reflect negative caching configuration to make it 
clearer. In so doing, I had to recode the evaluation of `negative_caching`. I 
attempted to keep the value the same while renaming it to 
`is_cacheable_and_negative_caching_is_enabled` to clarify its intent. In doing 
so, I missed that the previous nature of `negative_caching` was to be false for 
positive status codes. Therefore it doesn't behave the same and the branch 
@masaori335 references now behaves differently, being followed in cases it 
wouldn't have before. That sounds to me very likely the cause of the problem 
he's reporting.
   
   The fix will be to adjust the evaluation of 
`is_cacheable_and_negative_caching_is_enabled` to match the previous behavior 
of `negative_caching`.
   
   I'll work with @masaori335 on a patch for this and verify whether this fixes 
the leak he's seeing.
   
   Thank you @masaori335 for the detailed observations.


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