** Changed in: systemd (Ubuntu Bionic)
Status: Triaged => Fix Committed
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https://bugs.launchpad.net/bugs/1739672
Title:
Regression in getaddrinfo(): calls block for much longer on Bionic
(compared to Xenial), please disable LLMNR
Status in glibc package in Ubuntu:
Invalid
Status in linux package in Ubuntu:
Invalid
Status in systemd package in Ubuntu:
Fix Committed
Status in glibc source package in Bionic:
Invalid
Status in linux source package in Bionic:
Invalid
Status in systemd source package in Bionic:
Fix Committed
Bug description:
When testing MAAS on Bionic, we noticed sluggish performance that we
could not immediately explain.
After comparing the results from a run of the test suite on Xenial to
a run on Bionic, we determined that the slowdowns had to do with DNS
lookups. In particular, if MAAS attempts to resolve a hostname using
getaddrinfo() and the call fails, on Xenial the negative result is
returned in a fraction of a second. On Bionic, the negative result is
returned in ~1.6 seconds, according to some measures.
### To run the test ###
git clone https://github.com/mpontillo/test-getaddrinfo
cd test-getaddrinfo
make
### Results on Xenial ###
$ time ./test not-a-real-hostname
Trying to resolve: not-a-real-hostname
getaddrinfo errno: Success
getaddrinfo() return value: -2 (Name or service not known)
real 0m0.015s
user 0m0.000s
sys 0m0.000s
### Results on Bionic ###
$ time ./test not-a-real-hostname
Trying to resolve: not-a-real-hostname
getaddrinfo errno: Resource temporarily unavailable
getaddrinfo() return value: -3 (Temporary failure in name resolution)
real 0m1.609s
user 0m0.004s
sys 0m0.000s
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