Maximum value of timestamp

Question

I am using Python 3.6.0 on Windows 10 x64.

I just found that in time.ctime(seconds), seconds parameter has an implicit maximum value, which is 32536799999, almost equals to 2^34.92135.

Is that the maximum value?

The error message just says it's an invalid number.

>>> import time
>>> time.ctime(32536799999)
>>> 'Mon Jan 19 15:59:59 3001'
>>> time.ctime(32536799999+1)
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
OSError: [Errno 22] Invalid argument

I googled and looked on Python documentation, but I didn't find anything about it. And I'm going to check this problem on Ubuntu in my lab.

Answer 1

The time documentation doesn't mention any limits, but the datetime documentation does:

fromtimestamp() may raise OverflowError, if the timestamp is out of the range of values supported by the platform C localtime() or gmtime() functions, and OSError on localtime() or gmtime() failure.

[...]

Naive datetime instances are assumed to represent local time and this method relies on the platform C mktime() function to perform the conversion. Since datetime supports wider range of values than mktime() on many platforms, this method may raise OverflowError for times far in the past or far in the future.

Then we head over to the Windows documentation:

_localtime64, which uses the __time64_t structure, allows dates to be expressed up through 23:59:59, December 31, 3000, coordinated universal time (UTC), whereas _localtime32 represents dates through 23:59:59 January 18, 2038, UTC.

localtime is an inline function which evaluates to _localtime64, and time_t is equivalent to __time64_t. If you need to force the compiler to interpret time_t as the old 32-bit time_t, you can define _USE_32BIT_TIME_T. Doing this will cause localtime to evaluate to _localtime32. This is not recommended because your application may fail after January 18, 2038, and it is not allowed on 64-bit platforms.

All the time-related functions (including ctime) work the same way. So the max date you can reliably convert between timestamps on Windows 10 is 3000-12-31T23:59:59Z.

Trying to get a platform-independent max timestamp is difficult.