On Jun 21, 8:42 am, Martin <[email protected]> wrote:
> On Jun 19, 7:37 pm, Tim Bunce <[email protected]> wrote:
>
> > On Fri, Jun 18, 2010 at 08:39:47AM -0700, Martin wrote:
> > > perl -V for broken case:
>
> > > -DDEBUGGING=-g -Doptimize=-O2
>
> > That's a curious configuration.
>
> Not sure where it came from on this machine - it may be as installed
> by Ubuntu. The newer 5.10.1 was built by me using all defaults.
>
> > On the plus side it does mean the binary
> > will have symbols. So you could use a sampling profiler[1]to probe where
> > perl is spending its time.
>
> > Tim.
>
> > [1] Likehttp://oprofile.sourceforge.net/about/
>
> I'll look in to that.
>
> So far I have been unable to reproduce this is a smaller test case but
> I am continuing to try.
>
> Martin
OK, I've found the problem and it has nothing to Perl versions. It is
taint checking. The one that was taking ages was running with -t from
init and I forgot that and I was running it manually without -t.
Now I am even more suspicious of the concatentation line rather than
the ref(x) line taking the time. Since Tim found a line was taking
more and more ticks and the concatenation adds 4K each time to 32Mb it
almost sounds like taint checking is expensive and doing something
every time a chunk is added to the string.
I'm very sorry I forgot about taint checking. This is the second issue
we've found like this. I'm really going off taint mode quickly.
I can now reproduce with this:
create a file.dat file in your apache htdocs and make it around 32Mb
in size then run this:
use LWP::UserAgent;
use HTTP::Request;
my $ua = LWP::UserAgent->new();
$get = HTTP::Request->new('GET', 'http://localhost/file.dat');
my $r = $ua->request($get);
print length($r->decoded_content);
with and without taint checking. I should also add our Apache
returns .dat files as UTF-8 encoded.
Is this something I should report elsewhere?
Martin
--
You've received this message because you are subscribed to
the Devel::NYTProf Development User group.
Group hosted at: http://groups.google.com/group/develnytprof-dev
Project hosted at: http://perl-devel-nytprof.googlecode.com
CPAN distribution: http://search.cpan.org/dist/Devel-NYTProf
To post, email: [email protected]
To unsubscribe, email: [email protected]
