Public bug reported: 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 ** Affects: glibc (Ubuntu) Importance: Undecided Status: New ** Affects: linux (Ubuntu) Importance: Undecided Status: Incomplete ** Affects: systemd (Ubuntu) Importance: Undecided Status: New ** Tags: xenial ** Also affects: systemd (Ubuntu) Importance: Undecided Status: New ** Also affects: glibc (Ubuntu) Importance: Undecided Status: New -- You received this bug notification because you are a member of Ubuntu Desktop Bugs, which is subscribed to systemd in Ubuntu. https://bugs.launchpad.net/bugs/1739672 Title: Regression in getaddrinfo(): calls block for much longer on Bionic (compared to Xenial) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/glibc/+bug/1739672/+subscriptions -- desktop-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/desktop-bugs
