Drop support for EOL Python 2.6

[hugovk]

#1053 says to drop Python 2.6 support in unit tests and scripts, and to issue a deprecation warning in psutil.

In case or until you want to go further, this also removes Python 2.6 code, plus already dropped 3.2-3.3.

[giampaolo]

Can you change this so that set literals are not used? This way psutil can still be imported on python 2.6. Basically I'm looking to implement the original #1053 plan.

[hugovk]

Done!

[giampaolo]

why remove instructions for 2.7 and 3.4?

[hugovk]

Oops, mistaken removal of 2.7 along with 2.6, and 3.4 is still there, just 3.3 removed.

[giampaolo]

Instead of doing this can you please change all other test files and import unittest directly instead of from psutil.test import unittest?

[giampaolo]

Actually I retract, sorry. I think it is better to hold off on this a little while longer. Stats for Python 2.6 show 1% usage add 29,737 downloads in the last 30 days, which is about 30x times Python 3.3 usage.
Somewhat that makes me feel uncomfortable.

~/svn/psutil {master}$ GOOGLE_APPLICATION_CREDENTIALS=pypinfo-5264aad62c1c.json pypinfo --percent  psutil pyversion
python_version percent download_count 
-------------- ------- -------------- 
2.7              82.4%      2,519,940 
3.5               8.3%        254,540 
3.6               3.9%        118,078 
3.4               2.2%         66,466 
None              2.2%         66,389 
2.6               1.0%         29,737 
3.7               0.0%          1,309 
3.3               0.0%          1,079 
1.17              0.0%            789 
3.2               0.0%             48 
2.8               0.0%              3 
2.4               0.0%              2 

~/svn/psutil {master}$ GOOGLE_APPLICATION_CREDENTIALS=pypinfo-5264aad62c1c.json pypinfo --percent  psutil system distro
system_name distro_name                     percent download_count 
----------- ------------------------------- ------- -------------- 
Linux       Ubuntu                            58.9%      1,792,630 
Linux       Debian GNU/Linux                  11.4%        345,813 
Linux       CentOS Linux                       5.7%        174,088 
Linux       None                               5.3%        162,519 
Windows     None                               4.6%        141,227 
None        None                               4.0%        120,350 
Linux       CentOS                             3.2%         96,795 
Linux       debian                             2.0%         60,222 
Linux       Amazon Linux AMI                   1.3%         40,117 
Darwin      macOS                              1.1%         33,870 
Linux       Red Hat Enterprise Linux Server    0.6%         19,573 
Linux       Fedora                             0.6%         16,956 
Linux       Alpine Linux                       0.3%         10,234 
Linux       openSUSE Leap                      0.3%          7,785 
Linux       Raspbian GNU/Linux                 0.2%          5,180 
Linux       Kali GNU/Linux                     0.1%          4,293 
Linux       Oracle Linux Server                0.1%          3,953 
Linux       RedHatEnterpriseServer             0.1%          3,337 
Linux       SLES                               0.1%          3,332 
Darwin      OS X                               0.1%          3,130 

[hugovk]

Those numbers include mirrors too. How are they with the --pip switch?

[giampaolo]

~/svn/psutil {master}$ GOOGLE_APPLICATION_CREDENTIALS=pypinfo-5264aad62c1c.json pypinfo --percent --pip  psutil pyversion
python_version percent download_count 
-------------- ------- -------------- 
2.7              84.7%      2,489,139 
3.5               8.5%        249,424 
3.6               3.9%        115,803 
3.4               1.8%         52,619 
2.6               1.0%         28,810 
3.7               0.0%          1,063 
3.3               0.0%          1,002 
3.2               0.0%             22 
None              0.0%             12 
2.8               0.0%              3 

[hugovk]

👍 Thanks, more or less the same. Just let me know if/when you're ready for updates to this.

[giampaolo]

Thank you and sorry for wasting your time. I'll ping you for sure when the time comes.

[hugovk]

Just to keep an eye on the trend, here's the pip installs from PyPI for July 2018:

python_version	percent	download_count
3.5	51.94%	1,171,601
2.7	39.47%	890,376
3.6	6.11%	137,743
3.4	1.74%	39,351
3.7	0.39%	8,871
2.6	0.33%	7,541
3.3	0.01%	137
3.8	0.00%	7
None	0.00%	4
2.8	0.00%	2
Total		2,255,633

Source: pypinfo --start-date 2018-07-01 --end-date 2018-07-31 --percent --markdown psutil pyversion

(--pip is now implicit in pypinfo; use --all to show downloads by all installers, not only pip.)

(Really nice to see Python 3 now accounts for 60%! Up from 12% in October!)