On Wed, 18 Jan 2006, Chase Venters wrote:
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
What is "/usr/share/zoneinfo/right" and how does it differ from
"/usr/share/zoneinfo"?
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.
Recurrences are not simple at all, and I'm hardly surprised that using
them things makes page rendering much slower. But without a description of
what you're trying to achieve, and how you are doing it, I can't offer any
suggestions.
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.
Actually, I think it has to do with the cost of passing data across the
Perl <-> C boundary. From what I've heard, this is somewhat costly, so the
C code has to be enough faster to really make a difference.
That said, I tried that optimization a _long_ time ago, so it might be
possible to try again.
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.
Daisuke Maki tried making all the DT::TZ modules use XS, and in fact went
so far as to turn them into C-based data structures that were primarily
accessed via XS. Strangely, this was also slower and more memory-intensive
than the Perl version.
I think there's a branch for this in the DateTime CVS repo. I'd love if
other folks could take a look at it and see if there is some way to make
it faster and smaller. It seems like it should be possible, so maybe
there's some obvious fix that Daisuke and I missed.
Other than that, I don't know that the DateTime.pm module has any obvious
problem spots, but I haven't profiled it either, so I'm pretty much
talking out my rump.
-dave
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