| Puppet Version: puppet-5.5.10-5.el8ost
Puppet Server Version: N/A
OS Name/Version: Centos 8 A system that has many containers (~1000) will make /proc/mounts rather large (700-900 kbytes). Running any trivial puppet command will take a very long time there due to the following line:
https://github.com/puppetlabs/puppet/blob/master/lib/puppet/util/selinux.rb#L210 In there we're reading /proc/mounts 1024 bytes at the time, which is clearly suboptimal in this case (but also in most default cases as /proc/mounts is rarely < 1024 bytes these days on most modern linux systems). On such an environment we will observe:
[root@database-0 ~]# time puppet apply --noop --detailed-exitcodes --color=false -e 'file {"/tmp/foobar": content => "baz" } '
Notice: Compiled catalog for database-0.redhat.local in environment production in 0.16 seconds
Notice: /Stage[main]/Main/File[/tmp/foobar]/ensure: current_value absent, should be file (noop)
Notice: Class[Main]: Would have triggered 'refresh' from 1 events
Notice: Stage[main]: Would have triggered 'refresh' from 1 events
Notice: Applied catalog in 0.05 seconds real 5m43.258s
user 5m7.929s
sys 0m5.603s Increasing the read size to 1024 ** 2 provides immediate benefits:
[root@database-0 ~]# time puppet apply --noop --detailed-exitcodes --color=false -e 'file {"/tmp/foobar": content => "baz" } '
Notice: Compiled catalog for database-0.redhat.local in environment production in 0.11 seconds
Notice: /Stage[main]/Main/File[/tmp/foobar]/ensure: current_value absent, should be file (noop)
Notice: Class[Main]: Would have triggered 'refresh' from 1 events
Notice: Stage[main]: Would have triggered 'refresh' from 1 events
Notice: Applied catalog in 0.13 seconds real 1m22.954s
user 0m50.423s
sys 0m5.115s In such an environment strace confirms that the number of small read() calls goes from:
[root@database-0 ~]# grep -ir -e 'read(7.*1024' /tmp/strace-puppet.txt |wc -l
231381 To:
[root@database-0 ~]# grep -ir -e 'read(7.*1024' /tmp/strace-puppet-after.txt |wc -l
810 |
