Download speed display shows last reported value instead of average after finishing

[ssiano]

Description

The pip wheel download speed seems to be reported incorrectly, as shown here in my download_speed venv:

ss@ld:~/venv/PY3/download_speed$ pip list
Package    Version
---------- -------
pip        21.3.1
setuptools 58.5.1
wheel      0.37.0
(download_speed) 

ss@ld:~/venv/PY3/download_speed$ pip wheel torch==1.9.0
Looking in indexes: https://pypi.COMPANY.com/simple/
Collecting torch==1.9.0
  Downloading https://pypi.COMPANY.com/packages/packages/a1/1f/a372f2e9f0a54fc479fcee3ac072f8cd5091054e9d7293dd4372338e5277/torch-1.9.0-cp36-cp36m-manylinux1_x86_64.whl (831.4 MB)
     |████████████████████████████████| 831.4 MB 58 kB/s               
Collecting typing-extensions
  Downloading https://pypi.COMPANY.com/packages/packages/74/60/18783336cc7fcdd95dae91d73477830aa53f5d3181ae4fe20491d7fc3199/typing_extensions-3.10.0.2-py3-none-any.whl (26 kB)
Collecting dataclasses
  Downloading https://pypi.COMPANY.com/packages/packages/fe/ca/75fac5856ab5cfa51bbbcefa250182e50441074fdc3f803f6e76451fab43/dataclasses-0.8-py3-none-any.whl (19 kB)
Saved ./torch-1.9.0-cp36-cp36m-manylinux1_x86_64.whl
Saved ./dataclasses-0.8-py3-none-any.whl
Saved ./typing_extensions-3.10.0.2-py3-none-any.whl
(download_speed)

During the download, the speed was reported to be around 100 MB/s, and the download took around 10 seconds, but right as the download finished, the speed value changed to 58 kB/s.

Here's the same, but using time:

ss@ld:~/venv/PY3/download_speed$ time pip wheel torch==1.9.0
Looking in indexes: https://pypi.COMPANY.com/simple/
Collecting torch==1.9.0
  Downloading https://pypi.COMPANY.com/packages/packages/a1/1f/a372f2e9f0a54fc479fcee3ac072f8cd5091054e9d7293dd4372338e5277/torch-1.9.0-cp36-cp36m-manylinux1_x86_64.whl (831.4 MB)
     |████████████████████████████████| 831.4 MB 58 kB/s               
Collecting dataclasses
  Downloading https://pypi.COMPANY.com/packages/packages/fe/ca/75fac5856ab5cfa51bbbcefa250182e50441074fdc3f803f6e76451fab43/dataclasses-0.8-py3-none-any.whl (19 kB)
Collecting typing-extensions
  Downloading https://pypi.COMPANY.com/packages/packages/74/60/18783336cc7fcdd95dae91d73477830aa53f5d3181ae4fe20491d7fc3199/typing_extensions-3.10.0.2-py3-none-any.whl (26 kB)
Saved ./torch-1.9.0-cp36-cp36m-manylinux1_x86_64.whl
Saved ./dataclasses-0.8-py3-none-any.whl
Saved ./typing_extensions-3.10.0.2-py3-none-any.whl

real    0m11.480s
user    0m7.084s
sys     0m2.468s
(download_speed)

Again, the speed was about 100 MB/s, but the output is showing 58 kB/s.

Expected behavior

I would expect the output to show the correct download speed, e.g.,

338e5277/torch-1.9.0-cp36-cp36m-manylinux1_x86_64.whl (831.4 MB)
     |████████████████████████████████| 831.4 MB 100 MB/s

pip version

21.3.1

Python version

3.6.8

OS

Linux 4.4.0-206-generic #238~14.04.1-Ubuntu SMP Wed Mar 17 06:45:15 UTC 2021 x86_64 x86_64 x86_64 GNU/Linux

How to Reproduce

pip wheel torch==1.9.0

If the wheel is not downloaded, then you may need to do pip cache purge first.

Output

No response

Code of Conduct

• I agree to follow the PSF Code of Conduct.

[uranusjr]

I don't think there's anything wrong with the display. We're dealing network here, and this kind of "slowing down before finishing" is very common. If anything, pip can make the download speed disappear after it finishes, if that's what you worry about.

[ssiano]

Thanks for the explanation and changing the title, @uranusjr.

Since the last reported value may be 1/1,000th of the average value, maybe it is best not to display it.

An average speed would be even nicer, and would turn this issue into a feature request.