[rt-devel] REST performance drop after upgrade from 4.2.9 to 4.2.10

[Christian Loos]

Am 31.03.2015 um 19:54 schrieb Alex Vandiver:
> You've profiled the right thing, but not looked at the correct output
> from NYTProf.  Namely, all this says is "7.24s were spent
> in /REST/1.0/show".  You'll need to drill down into there to find out
> where the time is spent.
> 
> Since you're looking for a regression, I suggest you profile both
> 4.2.10 and 4.2.9 (using the same steps you did above) and explore both
> profile outputs in parallel, looking for where the extra 2.5s is coming
> from.

OK, I found the bad guy: w3m ;-)

As part of our RT 4.2.10 upgrade I installed HTML::FormatExternal.
So we use w3m for HTML2Text conversions.

NYTProf shows for 4.2.9 (core formater)
# spent   141ms making 12 calls to
RT::Interface::Email::ConvertHTMLToText, avg 11.7ms/call

and for 4.2.10 (w3m formater)
# spent  10.1s making 12 calls to
RT::Interface::Email::ConvertHTMLToText, avg 840ms/call

which is called in RT::Transaction->Content.

A quick test of the other formaters just confirms what is already
mentioned in the commit [1]:
* core is the fastest (2.9s)
* elinks is the slowest (5.7s)
* the others are in between (4.6s)

So as long as you don't find an reliable Perl HTML2Text converter, I
think there isn't much we can do here.


Chris

[1] https://github.com/bestpractical/rt/commit/c40ba50