datetime.utcnow()
This call is returning an incorrect datetime, delayed from UTC/GMT by 1 hour (check in: http://www.worldtimeserver.com/current_time_in_UTC.asp).
Is it working like it should be?
For example, it's returning, right now:
2015-02-17 23:58:44.761000.
Current UTC time is: 00:58, not 23:58
I know I'm five years late, but I had the same problem tonight. In my experience, the solution to the problem was to use the aware UTC datetime:
utc_dt_aware = datetime.datetime.now(datetime.timezone.utc)
If you google "utcnow() wrong" this is the first result you get, so I thought it would be good to answer anyway.
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.
The utcnow is deprecated
Replace this
datetime.utcnow()
With this
from datetime import datetime, timezone
datetime.now(timezone.utc)
Problem only occurs with utc time (Python3).
e.g. System time:
$ date
Wed Jul 15 10:44:26 BST 2015
Python time correct when using datetime.now():
>>> datetime.now()
datetime.datetime(2015, 7, 15, 10, 44, 30, 775840)
...But incorrect by one hour when using datetime.utcnow():
>>> datetime.utcnow()
datetime.datetime(2015, 7, 15, 9, 44, 32, 599823)
UTC's problem is it doesn't know my timezone.
You have to tell it, with the help of a timezone module called pytz:
>>> import pytz
>>> mytz = pytz.timezone('Europe/London')
>>> pytz.utc.localize(datetime.utcnow(), is_dst=None).astimezone(mytz)
datetime.datetime(2015, 7, 15, 11, 3, 43, 688681, tzinfo=<DstTzInfo 'Europe/London' BST+1:00:00 DST>)
References:
pytz - Converting UTC and timezone to local time
http://sweemengs-tech-world.blogspot.co.uk/2010/05/get-correct-datetime-value-for-python.html
utcnow() is incorrect? Unless your local timezone has zero utc offset; utc time will be different from the local time. Unrelated: you could use datetime.now(timezone), to get the current time in the given timezone. The references that you've provided are not good. For the first one; read my comments there.utcnow() returns datetime that is different from now(): "local time = utc time + utc offset"utcnow() is the same around the world (+/- clock sync.). It does not matter what is your local timezone; utc time remains the same e.g., it is now 2015-07-16T23:41:30Z (UTC). If you run datetime.utcnow() on your computer then you should get similar time regardless of your timezone (if you are on a POSIX system; you could easily change your timezone using TZ envvar and see for yourself that utcnow() does not change (now() is likely to change if you change your local timezone). .utcnow() may jump by around 26 seconds if you use "right" timezone but it is another issue.
I know I am tremendously late in replying to this.
I have tried doing this recently and therefore I suggest using datetime.now() instead of datetime.utcnow(). For my simple application that works fine.
time.timezonesay, and is it the right offset (in seconds) for your timezone?time.time(),time.gmtime(),GetSystemTimeAsFileTime()consistent with each other on your machine?