I wonder whether we should really support commenting of part lines - it is supported in some ini file implementations but isn't part of the generally applicable syntax rules.

Why not? In MariaDB/MySQL's my.cnf this is implemented, too. This is not an absolut must-have but I was just wondering why it stopped working with the MaxScale 1.2 Release.

Purely to keep options open. It seems very much of a "nice to have" for some people - others would never expect it. Where possible, it is nice to either standardise on as few parsing algorithms as possible or to use standard libraries for analysing stuff like the config. Also bearing in mind platform support. But I can't say I've done any research on actual resources.

I tested with the following config in MaxScale 1.1.1.

[maxscale]

threads=4

[monitor]

type=monitor

module=mysqlmon

servers=server1 #,server2

user=maxuser

passwd=maxpwd

[rw]

type=service

router=readconnroute

servers=server1,server2

user=maxuser

passwd=maxpwd

[rw_listener]

type=listener

service=rw

protocol=MySQLClient

port=3306

[server1]

type=server

address=10.0.2.2

port=3000

protocol=MySQLBackend

[server2]

type=server

address=10.0.2.2

port=3001

protocol=MySQLBackend

Here is the relevant line in the error log.
2015-07-20 09:26:38 Error: Unable to find server 'server1 #' that is configured in the monitor 'monitor'.

This was tested with the 1.1.1 RPM on Centos 6.

croser Did you use 1.1.1 or 1.1 when you tested this?

I used 1.1.1 but now I'm not able to reproduce it. I always get the same error like you did when testing with 1.1.1.

This is definitely still an issue. This

log_info=0  #turn this off unless debugging

Will turn on logging of info messages.
It's clearly documented in the wiki:

"Comments are defined by prefixing a row with a hash (#). Trailing comments are not supported."

And obviously still out of alignment with every other mariadb or mysql project. Please consider reopening as a feature request to improve or replace the config file parser.