surprising time shift for python call

Question

I'm using the following code in Python 2.5.1 to generate a UTC timestamp from a string representation of a date:

time.mktime(time.strptime("2009-06-16", "%Y-%m-%d"))

The general result is: 1245103200 (16.6.2009 0:00 UTC or 15.6.09 22:00:00, if you're in my time zone).

But now, I found that on some computers running Windows XP, this statement would generate a time shifted by 1 hour, 1 minute and 1 second: 1245099539 (15.6.2009 22:58:59 UTC or 15.6.09 20:58:59 in my time zone).

DST and time zone do not seem to be the cause of the problem, because the time shift seems to appear additionally to DST and time zone calculation.

Has anybody experienced the same behaviour or is able to describe what happens here?

Answer 1

What version of Python are you running? There are two bug descriptions here which sound a lot like what you are experiencing:

• http://bugs.python.org/issue5582
• http://mercurial.selenic.com/bts/issue1364

Answer 2

Found the answer myself:

When executing the following on the python command line interface, I get the result:

time.strptime("2009-06-16", "%Y-%m-%d")
time.struct_time(tm_year=2009, tm_mon=6, tm_mday=16, tm_hour=0, tm_min=0, tm_sec=0, tm_wday=1, tm_yday=167, tm_isdst=-1)

If I run the same command in an executable built with py2exe, it results in the following time structure:

time.struct_time(tm_year=2009, tm_mon=8, tm_mday=11, tm_hour=-1, tm_min=-1, tm_sec=-1, tm_wday=1, tm_yday=224, tm_isdst=-1)

The internal time structure apparently initializes differently on command line and when using py2exe. Fixed the problem by adding a midnight time to the command.