Re: DateTime performance

[Yitzchak Scott-Thoennes]

On Mon, Jan 16, 2006 at 06:21:54PM -0800, [EMAIL PROTECTED] wrote:
 One might hope that a script like this:
 
 test3
 #!/usr/bin/perl
 BEGIN {
 no lib qw|/usr/lib/perl5/site_perl/5.8.6/i386-linux-thread-multi /usr/ 
 lib/perl5/site_perl/5.8.5/i386-linux-thread-multi /usr/lib/perl5/ 
 site_perl/5.8.4/i386-linux-thread-multi /usr/lib/perl5/site_perl/ 
 5.8.3/i386-linux-thread-multi /usr/lib/perl5/site_perl/5.8.6 /usr/lib/ 
 perl5/site_perl/5.8.5 /usr/lib/perl5/site_perl/5.8.4 /usr/lib/perl5/ 
 site_perl/5.8.3 /usr/lib/perl5/site_perl /usr/lib/perl5/vendor_perl/ 
 5.8.6/i386-linux-thread-multi /usr/lib/perl5/vendor_perl/5.8.5/i386- 
 linux-thread-multi /usr/lib/perl5/vendor_perl/5.8.4/i386-linux-thread- 
 multi /usr/lib/perl5/vendor_perl/5.8.3/i386-linux-thread-multi /usr/ 
 lib/perl5/vendor_perl/5.8.6 /usr/lib/perl5/vendor_perl/5.8.5 /usr/lib/ 
 perl5/vendor_perl/5.8.4 /usr/lib/perl5/vendor_perl/5.8.3 /usr/lib/ 
 perl5/vendor_perl /usr/lib/perl5/5.8.6/i386-linux-thread-multi /usr/ 
 lib/perl5/5.8.6 .|;
 use lib qw|/usr/lib/perl5/site_perl/5.8.6/i386-linux-thread-multi / 
 usr/lib/perl5/site_perl/5.8.6 /usr/lib/perl5/site_perl /usr/lib/perl5/ 
 vendor_perl/5.8.6/i386-linux-thread-multi /usr/lib/perl5/vendor_perl/ 
 5.8.6 /usr/lib/perl5/vendor_perl /usr/lib/perl5/5.8.6/i386-linux- 
 thread-multi /usr/lib/perl5/5.8.6 .|;
 }
 use DateTime;
 
 Might improve the situation. However even this has no significant  
 improvement and from additional traces it doesn't actually stop perl  
 from using the built in paths.

Then no lib isn't doing what you want.  Try just:

BEGIN { @INC = grep !/5\.8\.[0-5]/, @INC }

Re: DateTime performance

[Yitzchak Scott-Thoennes]

On Wed, Jan 18, 2006 at 08:38:13AM -0800, [EMAIL PROTECTED] wrote:
 Then no lib isn't doing what you want.
 
 Agree. But, that is the point. Outside of recompiling perl with new  
 paths or significantly altering DateTime to use far fewer  
 dependancies nothing can really be done.
 
 test4
 #!/usr/bin/perl
 BEGIN { @INC = grep !/5\.8\.[0-5]/, @INC }
 use DateTime;

Do your traces show it still searching all the removed paths?
There's no way the above should be doing that, unless you're
loading DateTime earlier, via sitecustomize.pl or $PERL5OPT?

Re: DateTime performance

[matthew]

Then no lib isn't doing what you want.


Agree. But, that is the point. Outside of recompiling perl with new  
paths or significantly altering DateTime to use far fewer  
dependancies nothing can really be done.


test4
#!/usr/bin/perl
BEGIN { @INC = grep !/5\.8\.[0-5]/, @INC }
use DateTime;

[EMAIL PROTECTED] tmp]$ time perl test4

real0m5.780s
user0m5.524s
sys 0m0.188s

Matthew

Re: DateTime performance

[matthew]

Do your traces show it still searching all the removed paths?


yes


There's no way the above should be doing that, unless you're
loading DateTime earlier, via sitecustomize.pl or $PERL5OPT?


Neither of the items you have identified are used in any way during  
these tests. I would expect if either of those had been the issue  
then even test1 would be slow.


Regards,
Matthew

XS Leap second questions

[Chase Venters]

Greetings fellow Perl hackers,
I'm attracted to DateTime's very comprehensive approach at dealing with 
time 
(which I personally consider to be one of the biggest annoyances and 
challenges in programming).
Unfortunately, I've been plagued by an oddity in the way DateTime 
handles 
leap seconds in face of the Olson timezone database for some time. This shows 
up as test failures:

t/04epoch...NOK 12# Failed test (t/04epoch.t at line 40)
#  got: '997120978'
# expected: '997121000'
t/04epoch...NOK 14# Failed test (t/04epoch.t at line 43)
#  got: '2'
# expected: '3'
t/04epoch...NOK 20# Failed test (t/04epoch.t at line 81)
#  got: '1049160580'
# expected: '1049160602'
t/04epoch...NOK 22# Failed test (t/04epoch.t at line 84)
#  got: '29'
# expected: '30'
t/04epoch...NOK 24# Failed test (t/04epoch.t at line 90)
#  got: '1049167780'
# expected: '1049167802'
t/04epoch...ok 32/32# Looks like you failed 5 tests of 32.
t/04epoch...dubious

This happens when /etc/localtime is linked to a timezone 
in /usr/share/zoneinfo/right as opposed to /usr/share/zoneinfo. The problem 
bites me in the ass, unfortunately, because I tend to store date / time 
values in SQL as an epoch rather than a native type (less back and forth 
conversion required). This can result in my events drifting 22 seconds, etc.
Also, it's been clear to me that using DateTime heavily is a good way 
to 
quickly kill performance. Pages that took 20ms to render jump to 500ms when I 
try to do something simple like apply a recurrence set to a month.
I started peering into DateTime internals and have noticed that the xs 
seems 
a little... lite? Curiously, I read the text supplied with the distribution 
and noticed this:

NOTE TO FUTURE DEVELOPERS:

Attempting to implement add_duration in XS actually seemed to slow
date math operations down.  Sad but true.

Curious - what was the strategy? What do you assume to be the 
bottleneck? C 
has *got* to be faster at math than Perl, so I have a feeling the above 
remark is specific to a particular implementation approach.
Along those lines, are there any known outstanding areas where DateTime 
could 
use some optimization? I'm handy with C, very handy with Perl and somewhat 
capable with XS... I'd like to help.

Thanks,
Chase Venters