Only show the head of the outputs and ensure iopub outputs are correctly displayed

[echarles]

References

Fixes #10045

Code changes

We need to take into account the iopub messages when stripping the output to only show the defined max number of outputs.

This PR takes those messages into account. To achieve this, we also had to remove the display of the tail.

User-facing changes

The outputs are correctly displayed when running e.g.

for i in range(100):
    for x in range(10):
        print(x, flush=True)
    for x in range(10):
        print(x, file=sys.stderr, flush=True)

the tail is not more displayed (all outputs can still be seen if the user clicks on the message Click on this message to get the complete output.)

Backwards-incompatible changes

None

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[fcollonval]

Thanks @echarles I let some minor suggestions otherwise it works as expected.

[echarles]

Thx a lot @fcollonval for the review. I have committed your suggestions.

[jtpio]

This needs a quick lint pass.

[echarles]

@fcollonval @jtpio The code in now linted and CI is green. This is ready for merge.

[fcollonval]

All green for me. Thanks @echarles

[github-actions]

Benchmark report

The execution time (in milliseconds) are grouped by test file, test type and browser.
For each case, the following values are computed: min <- [1st quartile - median - 3rd quartile] -> max.

The mean relative comparison is computed with 95% confidence.

Results table

Test file	large_code_notebook	large_md_notebook
open
chromium
actual	7167 <- [7540 - 7867 - 7965] -> 8239	3500 <- [3587 - 3643 - 3906] -> 4047
expected	6437 <- [7494 - 7828 - 7971] -> 8240	3496 <- [3590 - 3627 - 3724] -> 4174
Mean relative change	0.4% ± 1.1%	1.0% ± 1.3%
switch-from
chromium
actual	842 <- [912 - 965 - 1153] -> 1633	559 <- [611 - 826 - 863] -> 957
expected	826 <- [893 - 942 - 1148] -> 1581	559 <- [618 - 820 - 898] -> 951
Mean relative change	2.0% ± 4.3%	-0.7% ± 4.7%
switch-to
chromium
actual	947 <- [986 - 1006 - 1021] -> 1255	725 <- [832 - 851 - 864] -> 902
expected	943 <- [979 - 993 - 1008] -> 1112	713 <- [815 - 838 - 856] -> 902
Mean relative change	1.6% ± 1.0%	1.8% ± 1.6%
close
chromium
actual	997 <- [1074 - 1105 - 1460] -> 1593	670 <- [696 - 705 - 717] -> 853
expected	965 <- [1061 - 1109 - 1179] -> 1581	663 <- [691 - 703 - 713] -> 821
Mean relative change	2.9% ± 4.4%	0.6% ± 1.1%

Changes are computed with expected as reference.

[echarles]

Thx for the review and approval @fcollonval Will you merge this?

[fcollonval]

Thx for the review and approval @fcollonval Will you merge this?

Doing it now...

[fcollonval]

@meeseeksdev please backport to 3.2.x

[lumberbot-app]

Owee, I'm MrMeeseeks, Look at me.

There seem to be a conflict, please backport manually. Here are approximate instructions:

1. Checkout backport branch and update it.

git checkout 3.2.x
git pull

2. Cherry pick the first parent branch of the this PR on top of the older branch:

git cherry-pick -m1 d1c26138eaecfd21e388703e704215b345c1166c

3. You will likely have some merge/cherry-pick conflict here, fix them and commit:

git commit -am 'Backport PR #11457: Only show the head of the outputs and ensure iopub outputs are correctly displayed'

4. Push to a named branch:

git push YOURFORK 3.2.x:auto-backport-of-pr-11457-on-3.2.x

5. Create a PR against branch 3.2.x, I would have named this PR:

"Backport PR #11457 on branch 3.2.x (Only show the head of the outputs and ensure iopub outputs are correctly displayed)"

And apply the correct labels and milestones.

Congratulations — you did some good work! Hopefully your backport PR will be tested by the continuous integration and merged soon!

Remember to remove the Still Needs Manual Backport label once the PR gets merged.

If these instructions are inaccurate, feel free to suggest an improvement.

[echarles]

Thx for the merge @fcollonval

I have seen a need for a manual backport to 3.2.x and a branch in your repo. I have seen tags removed by @krassowski

To avoid confusion, I have opened #11509 which backport this fix to 3.2.x branch.

[krassowski]

I removed the tag because the backport PR was already opened by @fcollonval here: #11502 so your PR is a duplicate ;)

[echarles]

I removed the tag because the backport PR was already opened by @fcollonval here: #11502 so your PR is a duplicate ;)

Yeah, I was suspecting that, but for some reasons, I have not found @fcollonval PR... I will close mine. Better 2 than zero :)