trac.webkit.org: Some change sets show diffs and preferences pane, some do not

[Lucas Forschler]

We've recently upgraded the trac instance on trac.webkit.org.  I'm running into an issue where some change sets show diffs and preferences, while others do not. 

This can easily be reproduced by clicking various changeset links on the https://trac.webkit.org timeline

two examples:

https://trac.webkit.org/changeset/215036/webkit

    There is no diff preference pane on the top right

    There are no diffs displayed, only the summary

vs

https://trac.webkit.org/changeset/215038/webkit

    See the diff preferences pane on the top right

    Notice the file diffs are displayed on the page

I am not sure why we are seeing this. 

In my trac.ini I have the following, since I thought possibly the number of files was making the difference Alas, setting it high does not help

max_diff_bytes = 1000000

max_diff_files = 100

Any ideas?

Thanks,

Lucas

[RjOllos]

That is strange. What version of Trac were you running before the upgrade, when presumably the issue was not seen?

- Ryan

[Peter Suter]

On 06.04.2017 18:11, Lucas Forschler wrote:

We've recently upgraded the trac instance on trac.webkit.org.  I'm running into an issue where some change sets show diffs and preferences, while others do not. 

This can easily be reproduced by clicking various changeset links on the https://trac.webkit.org timeline

two examples:

https://trac.webkit.org/changeset/215036/webkit

    There is no diff preference pane on the top right

    There are no diffs displayed, only the summary

This changeset touched Source/WebKit2/ChangeLog, file size: 1.6 MB.

vs

https://trac.webkit.org/changeset/215038/webkit

    See the diff preferences pane on the top right

    Notice the file diffs are displayed on the page

I am not sure why we are seeing this. 

In my trac.ini I have the following, since I thought possibly the number of files was making the difference Alas, setting it high does not help

max_diff_bytes = 1000000

This limit may get triggered by the 1.6 MB ChangeLog file.

max_diff_bytes seems to get compared to the sum of an estimate per file.
https://trac.edgewall.org/browser/tags/trac-1.2/trac/versioncontrol/web_ui/changeset.py?marks=586,590#L578

This estimate seems to be based on the sum of the old and new file sizes.
https://trac.edgewall.org/browser/tags/trac-1.2/trac/versioncontrol/web_ui/changeset.py?marks=533-536#L533

So the diff size of the ChangeLog is (over)estimated at 1.6MB+1.6MB, exceeding the 1000000 max_diff_bytes.

But I can't see any recent changes in this behavior, so maybe I'm missing something.

The following proposed changes might improve this behavior though:
https://trac.edgewall.org/ticket/10267#comment:8

[RjOllos]

Good find. I created #12761 to add some logging so the issue is easier to discover.
https://trac.edgewall.org/ticket/12761

- Ryan
 

[Lucas Forschler]

We upgraded from something very ancient...  0.12.3

it's possible this reproduced back then, but I'm not certain.

Looks like the ChangeLog issue may be the culprit! I'll up the diff size and see if it goes away.