on 19/03/2007 16:15 Andriy Gapon said the following:

Strange problem: $ uname -srm FreeBSD 6.2-RELEASE-p2 amd64

$ zdump -v EST EST Sun Jan 26 08:29:52 -219 UTC = Sun Jan 26 03:29:52 -219 EST isdst=0 gmtoff=-18000 EST Mon Jan 27 08:29:52 -219 UTC = Mon Jan 27 03:29:52 -219 EST isdst=0 gmtoff=-18000 EST Fri Jan 1 04:59:59 -219 UTC = Thu Dec 30 23:59:59 -219 EST isdst=0 gmtoff=-18000 EST Fri Jan 1 05:00:00 -219 UTC = Fri Jan 1 00:00:00 -219 EST isdst=0 gmtoff=-18000 ^C ... Before each ^C zdump was hanging eating 100% CPU. Something about 64-bitness ?

Hmm. I hurried to assert that it was hanging, it was actually searching. It seems that zdump -v algorithm is to start with minimal time_t possible (large negative number in our case) and to go to maximum time_t using 12 hours increments and doing certain checks for DST jumps. Well, with 64-bit time_t start date is somewhere 200 milliard (10^9) years ago and end date is the same in the future, so iteration over those years takes quite a while. And tz db doesn't contain anything useful for too distant years anyway. I think that zdump should be optimized to limit its search range. At the very least for the start point - what is current estimate of the age of our Universe :-) -- Andriy Gapon