[jira] Commented: (DIR-182) Improvment in the way DN are treated

["Emmanuel Lecharny (JIRA)" <di...@incubator.apache.org>]

    [ http://issues.apache.org/jira/browse/DIR-182?page=comments#action_12370650 ] 

Emmanuel Lecharny commented on DIR-182:
---------------------------------------

A better solution would be to do a String comparizon into the DnComparator. It makes sense as the DN has already been normalized before being stored into the backend.

The performance increase is dramatic : for a bind request, the comparizon cost will be done around 670 times faster !

This approach has been already partially implemented month ago and is effective when two DN are equals : the server speed has been increased and is now 4 times faster than it was. In the previous list, all the DN that does not have a '*' are compared as strings. We just have to do the same thing for other elements.

> Improvment in the way DN are treated
> ------------------------------------
>
>          Key: DIR-182
>          URL: http://issues.apache.org/jira/browse/DIR-182
>      Project: Directory
>         Type: Improvement
>     Reporter: Emmanuel Lecharny

>
> We have mesured that DN parsing is the hot spot in the server : we spend around 80 % of server time to parse DNs.
> After having studied the way BindRequest does handle DN, we can say that for a single bind for the user "uid=admin,ou=system", we have more than 40 parsing done. Here is a list of all the parsing in the DnComparator.compare() method :
> (The '*' in front of each line shows where a parsing of both DN is done)
> * Compare 'ou=groups,ou=system' and 'uid=admin,ou=system'
> * Compare 'prefnodename=sysPrefRoot,ou=system' and 'uid=admin,ou=system'
> Compare 'uid=admin,ou=system' and 'uid=admin,ou=system'
> Compare 'uid=admin,ou=system' and 'uid=admin,ou=system'
> * Compare 'ou=groups,ou=system' and 'uid=admin,ou=system'
> * Compare 'prefnodename=sysPrefRoot,ou=system' and 'uid=admin,ou=system'
> Compare 'uid=admin,ou=system' and 'uid=admin,ou=system'
> Compare 'uid=admin,ou=system' and 'uid=admin,ou=system'
> * Compare 'ou=groups,ou=system' and 'ou=system'
> * Compare 'ou=interceptors,ou=configuration,ou=system' and 'ou=system'
> * Compare 'ou=configuration,ou=system' and 'ou=system'
> Compare 'ou=system' and 'ou=system'
> Compare 'ou=system' and 'ou=system'
> * Compare 'ou=groups,ou=system' and 'ou=system'
> * Compare 'ou=interceptors,ou=configuration,ou=system' and 'ou=system'
> * Compare 'ou=configuration,ou=system' and 'ou=system'
> Compare 'ou=system' and 'ou=system'
> Compare 'ou=system' and 'ou=system'
> * Compare 'ou=groups,ou=system' and 'ou=system'
> * Compare 'ou=interceptors,ou=configuration,ou=system' and 'ou=system'
> * Compare 'ou=configuration,ou=system' and 'ou=system'
> Compare 'ou=system' and 'ou=system'
> Compare 'ou=system' and 'ou=system'
> * Compare 'ou=groups,ou=system' and 'ou=system'
> * Compare 'ou=interceptors,ou=configuration,ou=system' and 'ou=system'
> * Compare 'ou=configuration,ou=system' and 'ou=system'
> Compare 'ou=system' and 'ou=system'
> Compare 'ou=system' and 'ou=system'
> * Compare 'ou=groups,ou=system' and 'ou=system'
> * Compare 'ou=interceptors,ou=configuration,ou=system' and 'ou=system'
> * Compare 'ou=configuration,ou=system' and 'ou=system'
> Compare 'ou=system' and 'ou=system'
> If we can change this compare function to work with Name instead of String we could have a huge improvment : more that 35x faster
> (I wrote a micro-bench to mesure the difference : around 36 times faster).
> As this is not the single place where we can gain time (we have a lot or String -> DN and DN -> String conversions during the Bind process), we would be able to handle Bind Request much much faster, too (being aware that we have a lot of other costly operaions that will nor allow a x40 improvment).
> My personnal guess is that we should be able to handle around 5000 binds per second against the current 300, but this is just a guess :)

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