Perform a binary search to find optimal size of DNS responses #4037
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Will fix hashicorp#4036 Instead of removing one by one the entries, find the optimal size using binary search. For SRV records, with 5k nodes, duration of DNS lookups is divided by 4 or more.
agent/dns.go
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| resp.Answer = originalAnswser[:median] | ||
| if hasExtra { | ||
| resp.Extra = originalExtra[:median] |
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Correct me if you think otherwise but I think lines 733 and 734 here are unnecessary as well as the originalIndex and originalExtra variables.
The hasExtra block should just be a call to syncExtra. slicing originalExtra should not do anything (other than eat a few cpu cycles) as syncExtra will just overwrite resp.Extra with a brand new slice of its making. Also since syncExtra doesn't modify the RR index there shouldn't be a need to hold the originalIndex and reset index to it.
So I would remove those two vars and those extra lines
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@mkeeler Yes, you are right, I was confused by a unit test at a given time, but since no modification is performed, it is safe. Done in next patch
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Damned unstable Travis CI |
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@pierresouchay If you are finished with this I will go ahead and merge it.
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Yes, I am done with it |
Will fix #4036
Instead of removing one by one the entries, find the optimal
size using binary search.
For SRV records, with 5k nodes, duration of DNS lookups is
divided by 4 or more.
Results with around 5k nodes on local agent, dev mode:
Before Optimization: SRV~100ms ; A ~25ms
After Optimization: SRV ~20ms ; A ~20ms