The issue is with the systemd resolver not with glibc.
With systemd-resolve IP in /etc/resolv.conf:
# This file is managed by man:systemd-resolved(8). Do not edit.
#
# 127.0.0.53 is the systemd-resolved stub resolver.
# run "systemd-resolve --status" to see details about the actual nameservers.
nameserver 127.0.0.53
$ time ./test not-a-hostname
Trying to resolve: not-a-hostname
getaddrinfo errno: No such file or directory
getaddrinfo() return value: -2 (Name or service not known)
real 0m10.076s
user 0m0.001s
sys 0m0.000s
Without systemd-resolve in /etc/resolv.conf. I changed it to point to my local
DNS server directly.
# This file is managed by man:systemd-resolved(8). Do not edit.
#
# 127.0.0.53 is the systemd-resolved stub resolver.
# run "systemd-resolve --status" to see details about the actual nameservers.
#nameserver 127.0.0.53
nameserver 192.168.1.1
$ time ./test not-a-hostname
Trying to resolve: not-a-hostname
getaddrinfo errno: No such file or directory
getaddrinfo() return value: -2 (Name or service not known)
real 0m0.097s
user 0m0.001s
sys 0m0.000s
** Changed in: glibc (Ubuntu)
Status: New => Invalid
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https://bugs.launchpad.net/bugs/1739672
Title:
Regression in getaddrinfo(): calls block for much longer on Bionic
(compared to Xenial)
Status in glibc package in Ubuntu:
Invalid
Status in linux package in Ubuntu:
Invalid
Status in systemd package in Ubuntu:
New
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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