Python datetime.utcnow() returning incorrect datetime

Question

datetime.utcnow()

This call is returning an incorrect datetime, delayed from UTC/GMT by 1 hour (check in: http://www.worldtimeserver.com/current_ti

Answer 1

datetime.utcnow() uses OS provided values.

datetime.utcnow() uses gettimeofday(2) or time.time() on Python 2 (and gmtime(3) to convert the result into broken-down time).

time.time() uses gettimeofday(2), ftime(3), time(2). Newer CPython versions may use clock_gettime(2), GetSystemTimeAsFileTime().

You could check the self-consistency as follows:

#!/usr/bin/env python
import time
from datetime import datetime, timedelta

print(datetime.utcnow())
print(datetime(1970, 1, 1) + timedelta(seconds=time.time()))
print(datetime(*time.gmtime()[:6]))

Here's (non-tested) code that calls GetSystemTimeAsFileTime() on Windows based on CPython source:

#!/usr/bin/env python
import ctypes.wintypes
from datetime import datetime, timedelta

def utcnow_microseconds():
    system_time = ctypes.wintypes.FILETIME()
    ctypes.windll.kernel32.GetSystemTimeAsFileTime(ctypes.byref(system_time))
    large = (system_time.dwHighDateTime << 32) + system_time.dwLowDateTime
    return large // 10 - 11644473600000000

print(datetime(1970, 1, 1) + timedelta(microseconds=utcnow_microseconds()))

Here's code that calls clock_gettime() on Python 2.